A review of the literature on livestock housing and manure manageme nt practices (K. Smith, ADAS, Defra project AC0114), updated with survey data on manure spreading practices from the BSFP (BSFP, 2022), and data from DAERA statistics for Northern Ireland (DAERA, 2022) was used as the basis for developing the 1990 to 2021 timeseries of livestock housing and manure management practices for each country (England, Wales, Scotland and Northern Ireland) from which a weighted average was derived for the UK. Underlying data sources include routine and ad-hoc surveys such as the Defra Farm Practices Surveys (Defra, 2022c) and published manure management surveys (Smith et al., 2000, 2001a, 2001b). The proportions of cattle manure management practices were based on a UK data synthesis by Smith and Williams (2016). The housing period for beef animals was derived from Parsons Within the sheep sector, all (100%) manure from the ewe housing period is assumed to be managed as solid farmyard manure with additions of straw bedding. All (100%) manure from the housing period is assumed to be stored for a period of several months as a field heap on grass before spreading to land. It is assumed that 75% of ewes associated with lowland

Agriculture (CRF Sector 3) 5 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 359 systems, 60% with upland systems, and 40% with hill systems are housed in the last weeks of pregnancy and that these breeding ewes are housed for 42 days prior to lambing, and that neither the ewe nor new-born lamb are housed post-lambing (Roderick, 2001). Management for other activities (e.g. shearing) were obtained from various sources ( Defra, 2004; Webb et For swine and other minor livestock, the inventory code was updated to include bedding N at housing before estimating emissions (it had been included after the emissions calculation). Poultry manure subsequently going to incinerati on in power stations is associated with N 2O directly from MRE UK 86; the amounts exported from Northern Ireland to be incinerated in DAs). The quantities going for incineration are deducted prior to calculations of emissions from land spreading. Manure types going to incineration are assumed to be broiler and turkey litter and the reported quantities incinerated are converted to a proportion of the total manure for these poultry categories based on estimated manure outputs per bird. 5.4.2.2.3 Indirect nitrous oxide emissions from MMS For estimation of indirect N 2O emissions from manure management, country -specific values for FracGASM and FracLEACH are used. FracGASM is derived directly as output from the UK N-flow model for each livestock x AWMS combination, as the sum of the NH3-N and NO-N emissions (further details can be found in the UK Informative Inventory Report). A country-specific value of 2.4% of manure N for FracLEACH is used, based on Nicholson et al. (2017) and applied only to solid manure heaps stored in fields. For manure heaps stored on concrete pads, the leachate is assumed to be collected and is subsequently included in the N content of liquid/slurry managed manure. Indirect emissions from manure manage ment due to volatilisation and leaching are then calculated according to IPCC (2006) equations 10.27 and 10.29, respectively, applying the IPCC 2019 refinement to the 2006 Guidelines default value (‘wet climate’) for EF4 (1.4%) and the IPCC 2006 Guidelines default value for EF5 (0.75%), as these are regarded as the most representative for UK conditions. Uncertainties and time-series consistency The uncertainty analysis in Annex 2 provides estimates of uncertainty per IPCC source The estimates of u ncertainties in emissions were calculated using Approach 2 (Monte Carlo simulation) described by the IPCC, applying uncertainty parameters that reflect the Tier 3 models used to derive the UK greenhouse gas inventory emission estimates. The uncertainties in the estimates of livestock data were provided by the devolved administrations, as they are The UK sector experts have reviewed the uncertainty parameters for the UK method for methane and nitrous oxide emissions from manure management during the 2023 submission. Models and associated uncertainties are now incorporated for minor livestock. The main change in the models since the last uncertainty run is moving the calculation of methane emissions from the housing phase to the storage pha se in order to fully represent emissions from anaerobic digestion. There are also changes to the activity data, for example the percentages of livestock on different housing systems / storage as well as the addition of some new housing types for poultry. T his includes improvements in how the animal waste management systems (AWMS) breakdown is parameterised. Agriculture (CRF Sector 3) 5 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 360 In previous inventories the uncertainty was assumed to be ±20 % for the AWMS breakdown but now estimates are based on analysis of the underlying data. Overall changes in uncertainty for this source category are as • For methane, uncertainties have o Scotland ±18.9% to ±11.6%; and o Northern Ireland ±15.9% to ±11.4% • For nitrous oxide, uncertainties have o Scotland ±27.3% to ±42.5%; and o Northern Ireland ±24.9% to ±30.9%. The uncertainty parameters will be kept under review for future submissions. Emissions are calculated from livestock population data and appropriate emission factors. The livestock population data are collected in the JAC, published annually by the devolved administrations (i.e. England, Wales, Scotland and Northern Ireland). These are long running publications and the compilers of the activity data strive to use consistent methods to produce the activity data.
The time -series consistency of these activity data is very good due to the Source-specific QA/QC and verification This source category is covered by the general QA/QC procedures, which are discussed in Source-specific recalculations Details of and justifications for recalculations to activity data and to emission factors are given

Agriculture (CRF Sector 3) 5 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 361 Category Source Name 1990 2020 1990 2020 Units Comment/Justification 3.B.1.1 Manure Methane 63.03 71.19 63.89 70.70 kt As ‘Enteric fermentation – Dairy cattle’ plus updated proportion of animals kept on slurry/FYM systems with fewer dairy cows on slurry systems in Wales from 2010 (interpolated from 1990-2010 so affects all years bar 1990) and more dairy cows kept on slurry for all years in Scotland; Updated slurry storage proportions for NI resulting in less slurry being stored in below ground tanks and lagoons and more being stored in above ground tanks (affects all years); Updated FYM storage proportions for all DAs resulting in more FYM being spread direct (stored in house) for S and NI with adjustments for all DAs in the amount of FYM stored in field heaps or steading (affects all years); Updated amount of manure destined for anaerobic digestion 3.B.1.1 Manure Methane 60.20 52.78 59.09 52.53 kt Very small correction to coded model dairy DMI vs CH4 relationship (affects all years); Replaced slaughter weight timeseries 3.B.1.3 Manure Methane 35.16 20.59 35.00 20.36 kt Updated FYM storage proportions for all DAs resulting in more FYM being spread direct (stored in house) for S and NI which is associated with a lower MCF (virtually no FYM in NI so little effect), alongside adjustments for all DAs in the amount of FYM stored in field heaps or steading (affects all years); Updated amount of manure destined for anaerobic digestion (from 2008) 3.B.1.4 Manure Methane 2.48 3.24 2.48 3.57 kt Updated quantities of litter going to anaerobic digestion (from 1991); Updated FYM storage proportions for all DAs (all years) 3.B.2.1 Manure Nitrous Oxide 1.1741 0.9917 1.1744 0.9881 kt Very small correction to coded model dairy DMI vs CH4 relationship (affects all years); Small changes in N excretion associated with changes to milk yield (from 2013) and slaughter weight updates (from 2008); Concentrate use updated for 2020 for E,W,S which has small effect on emissions from 2011 due to values being interpolated; Updated proportion of animals kept on slurry/FYM systems with fewer

Agriculture (CRF Sector 3) 5 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 362 Category Source Name 1990 2020 1990 2020 Units Comment/Justification dairy cows on slurry systems in Wales from 2010 (interpolated from 1990-2010 so affects all years bar 1990) and more dairy cows kept on slurry for all years in Scotland; Updated slurry storage proportions for NI and FYM storage proportions for all DAs which only affects indirect emissions because N2O emissions are calculated at the housing phase; Introduced 73% uptake of washing down of dairy cow collecting yards for E,W,S and 100% for NI (whole timeseries) 3.B.2.1 Manure Nitrous Oxide 5.17 4.39 5.16 4.30 kt Very small correction to coded model dairy DMI vs CH4 relationship (affects all years); Small changes in N excretion associated with changes to milk yield (from 2013) and slaughter weight updates (from 2008); Concentrate use updated for 2020 for E,W,S which affects emissions from 2011 due to values being interpolated; Updated proportion of dairy followers/beef kept on slurry systems with fewer animals on slurry systems in Wales from 2010 (interpolated from 1990-2010 so affects all years bar 1990) and more dairy follower/beef kept on slurry for all years in Scotland; Updated slurry storage proportions for NI and FYM storage proportions for all DAs which only affects indirect emissions because N2O emissions are calculated at the housing phase; Introduced 3% mitigation uptake of rigid covers on above ground tanks in NI from 2010 3.B.2.4 Manure Nitrous Oxide 0.93 0.75 0.93 0.76 kt N excretion values have been revised for 2016 (affects 2005 onwards as values are used in extrapolating for previous years and taking forward for future years); Updated FYM storage proportions for all DAs which only affects indirect emissions because N2O emissions are calculated at the housing phase 3.B.2.5 Manure Indirect N2O 2.28 1.80 2.24 1.78 kt As direct manure management above

Agriculture (CRF Sector 3) 5 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 363 Category Source Name 1990 2020 1990 2020 Units Comment/Justification 3.B.1.1 Manure Methane 22.13 38.43 22.43 38.16 kg/hd/year Reason for change as above 3.B.1.1 Manure Methane 6.49 6.97 6.37 6.93 kg/hd/year Reason for change as above 3.B.1.3 Manure Methane 4.66 4.06 4.64 4.02 kg/hd/year Reason for change as above 3.B.1.4 Manure Methane 0.018 0.018 0.018 0.020 kg/hd/year Reason for change as above 3.B.2.1 Manure Nitrous Oxide 0.4122 0.5353 0.4123 0.5334 kg/hd/year Reason for change as above 3.B.2.1 Manure Nitrous Oxide 0.558 0.579 0.556 0.567 kg/hd/year Reason for change as above 3.B.2.4 Manure Nitrous Oxide 0.0067 0.0041 0.0067 0.0042 kg/hd/year Reason for change as above

Agriculture (CRF Sector 3) 5 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 364 The methane implied emission factors from manure management for major categories such as dairy and other cattle in the UK inventory (38, 6.9 5 kg/head/year, respectively ) are higher than the IPCC default values (21, 6 kg/head/year, respectively). Values for sheep and swine (0.13 and 4.0 kg/head/year, respectively) are lower than IPCC (0.19 and 6 kg/head/year, Source-specific planned improvements Development of partial EF for nitrous oxide and methane emissions for the different manure management stages, i.e. separate EF for housing and storage, that also enable accounting of the impacts of duration and conditions of manure storage. Emission factors and activity data will continue to be reviewed including the use of more detailed emission factors and activity data to improve emission estimates and allow estimation of the effect of future mitigation policies.
Source included Method Emission Emissions sources 3D1: Direct N2O Emissions from 3D2: Indirect N2O Emissions from Key Categories 3D: Agricultural soils - N2O (L1, T1, L2, T2) Completeness A general assessment of completeness for the inventory is Emissions from the composting and subsequent land application of livestock manures are currently Not Estimated due to a lack of activity data. Emissions of nitrous oxide from agricultural soils are estimated using IPCC (2006) Tier 1 and 2 methodology (IPCC Equations 11.1, 11.2), implementing UK -specific EF and parameters (i) The use of inorganic fertiliser (ii) Application of livestock manures to land (iii) Application of sewage sludge and other organic sources to land

Agriculture (CRF Sector 3) 5 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 365 (iv) Urine and dung deposited by grazing animals in the field (v) Crop residues returned to soils (vii) Cultivation of histosols (organic soils) Indirect nitrous oxide emissions are estimated from 2 (viii) Atmospheric deposition of agricultural NOx and NH3 (from (i), (ii), (iii) and (iv)) (ix) Leaching and run-off of agricultural nitrate (from (i), (ii), (iii), (iv), (v) and (vi)). Further details on activity data and EF are given in Annex 3.3. 5.5.1.1 Source category significance, trends and drivers The total emissions of N2O in 2021 across all agriculture sources were 41.5 kt. Emissions have

Agriculture (CRF Sector 3) 5 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 366 production of nitrous oxide (N2O) from agriculture Sources leading to nitrous oxide ( N2O) emissions include slurry, farmyard manure (FYM), sewage sludge, digestates, fertiliser, and dung and urine depositions to grazed lands. Detailed information on some of the individual experiments that provided the data for the analysis can be found in reports (AC0114, AC0116) and journal articles (e.g. Bell et al., 2016a; Bell et al., 2016b; Bell et al., 2015; Sylvester-Bradley et al., 2015). Following the guidelines of the IPCC (2006) for the derivation of N2O EFs, all the data from the experiments were collected over a 12-month period. The static chamber methodology was used for emission measurement, which is consistent with the Global Research Alliance guidelines (de Klein and Harvey, 2012; Charteris et al., 2020). Data were collated by surface-spread and broadcast slurry, farmyard manure, dung and urine, and ammonium -based and urea -based fertilisers. In all experiments, a control treatment which received no organic or inorganic fertiliser was included. In all cases, as well as the emissions and the N application rates, data on the soil characteristics, total rainfall (RainYr, mm) and the average daily temperature for the 365 days associated with the experimental period were collated. The analysis was carried out by using REML regression using Genstat 17th Edition Release 17.1 VSN International Ltd., Oxford. With the exception of the fertiliser N category ‘Other N to grassland’, the EFs for fertiliser application, FYM, broadcast slurry and grazing were lower than the IPCC default value of 1%. Direct N2O emissions from fertiliser N applications are calculated using values of EF1 derived from UK -specific measurements (Topp et al., in prep ). Direct N 2O emission is related to fertiliser type, application rate and average annual rainfall, with the relationship for urea-based fertilisers as in equation 1. For all other fertiliser type s, the calculation involves fertiliser rate

Agriculture (CRF Sector 3) 5 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 367 applied and average annual rainfall (equation 2) (see small changes in parameters compared ln(𝐶𝑢𝑚𝑁2𝑂 + 1.63) = 0.8404(±0.06846) + 0.001518(±0.0001077) ∗ 𝑁𝑅𝑎𝑡𝑒 (eq.1) Ln(𝐶𝑢𝑚𝑁2𝑂 + 1.63) = 0.5700(±0.1107) − 0.0001942(±0.0001968) ∗ 𝑁𝑅𝑎𝑡𝑒 + 0.3962(±0.1326) ∗ 𝑅𝑎𝑖𝑛𝑌𝑟 + 0.003284(±0.0002291) ∗ 𝑁𝑅𝑎𝑡𝑒 ∗ 𝑅𝑎𝑖𝑛𝑌𝑟 (eq.2) CumN2O = cumulative annual N2O-N emission (g ha-1) NRate = rate at which fertiliser N is applied (kg ha-1) RainYr = annual average rainfall (m) limited to 0 to 1.3 m. EF are derived as shown in equation 3. ((𝐶𝑢𝑚𝑁2𝑂 𝑎𝑡 𝑠𝑝𝑒𝑐𝑖𝑓𝑖𝑒𝑑 𝑁𝑅𝑎𝑡𝑒 – 𝐶𝑢𝑚𝑁2𝑂 𝑎𝑡 𝑧𝑒𝑟𝑜 𝑁𝑅𝑎𝑡𝑒) / 𝑁𝑅𝑎𝑡𝑒 (eq.3) The correction multipliers to the total N 2O losses due to t he bias for the log transformation 1.011 and 1.02 for urea and ammonium nitrate application, respectively. The activity data for annual fertiliser applications are primarily obtained from the British Survey of Fertiliser Practice (BSFP) which provides sampled data from a stratified survey of farm types across Great Britain; these data are analysed and upscaled to generate UK -wide fertiliser application data by fertiliser type and crop type. In addition the BSFP data provide temporal information that enables analysis of the timing of fertilisers by type across the year; this added detail enables the UK method to reflect the different climatic conditions that prevail at the time of fertiliser application, which impacts upon the emissions. For a couple of fertiliser types that are not produced in the UK, the activity data are obtained from fertiliser import data. As a data validation step, the UK inventory team also consults with the farming industry, such as the Agricultural Industries Confederation (AIC ), to compare the inventory fertiliser activity data against other statistics that are gathered from suppliers. In some instances the inventory data do deviate from the industry statistics; the Inventory Agency continues to explore the reasons for these differences with the fertiliser suppliers, to seek any potential improvement in total fertiliser application per fertiliser type. 5.5.2.2 Application of livestock manures to land Emissions are calcula ted following IPCC methodology (2006, equation 11.1) using country - specific EFs. Proportions of managed manure N applied to GB cropland are derived from Smith (2012). Assumptions regarding proportions of manures spread to land for Northern Ireland were made based on data provided directly by DAERA (DAERA, 2021). The values assumed (see following paragraphs) are constant throughout the time series with the exception of poultry The nature of manure management differs between farm types such that more is retained on the farms with grazing livestock than for pig and poultry farms and also more is spread on grassland for those farm types than to arable crops.
In general, slurries are less likely to be transported long distances than solid manures. The fate of manure is estimated by considering spatial disaggregation as in the BSFP; for livestock is calculated according to Smith et al. (2015). On broiler and turkey farms a proportion is deducted to allow for that amount going to biomass power st ations and the remainder is assumed to be applied to land in the In the case of dairy, the UK inventory assumes for England, Wales and Scotland that, 24% slurry and 40% of FYM is spread to cropland. For Northern Ireland, 9.5% of slurry is spread to cropland and 25.5% of FYM is spread to cropland. In the case of beef cattle, for England,

Agriculture (CRF Sector 3) 5 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 368 Wales and Scotland it is assumed 12% is slurry and 33% FYM is spread to cropland and for Northern Ireland the values are 9.5% and 20% for slurry and FYM, respectively. For sheep, all (100%, as FYM) of managed manure is assumed to be spread to improved grassland as a simplification of actual practice. Based on statistical analyses of a limited number of survey records from the British Survey of Fertiliser Pract ice (2007 to 2012) for England and Wales (no survey records were available for Scotland and Northern Ireland, but the location of managed manure spreading is likely to be more similar to Wales than England, on the basis of the similarity of relative national crop and grass areas) we estimated that 87% of all managed manure from all sheep in the United Kingdom is spread to improved grassland, and 13% to crop. These percentages are based on assumptions from regional data (BSFP 2007-2012), where 94.7 % of mana ged sheep manure in Wales was spread to improved grassland and the remainder to crop; and that 77.5 % of managed sheep manure in England was spread to improved grassland and the remainder to crop. No survey records were available for Scotland and Northern Ireland, but the location of managed manure spreading is likely to be more similar to Wales than England, on the basis of the similarity of relative national crop and grass areas (England 50% grass; Wales 92% grass; Scotland 70% grass; and Northern Ireland 93% grass). The model assumption of 100% applied to grassland has no actual impact on the emission estimate. In the case of pigs, for England, Wales and Scotland, 54% slurry and 78% of FYM is spread to cropland. For Northern Ireland, 16% of slurry is spr ead to cropland and 78% of FYM is In the case of poultry, the percentage of layer manure and all other poultry manure spread to Defra, 2022c). Manure that has been sent to incineration is excluded from these data. The inventory model currently assumes that all (100%) of managed manure from minor livestock (horse, goat and deer) is spread to improved grassland. Country-specific direct N 2O EF values were derived from a large number of experiments distributed across the UK (Defra, 2016a, Defra, 2014b). Derived values for the direct N2O EF are 0.75, 0.33 and 1.01% of applied N for slurry, farmyard manure and poultry manure, respectively (Topp et al., in prep.) 5.5.2.3 Application of other organic sources to land Emissions of nitrous oxide are calculated Where Q is the quantity of organic material applied (m3), TN is the total nitrogen content of the material (kg m-3); EFN2O is the emission factor applied (as % of the TN applied). For sewage sludge and non-manure based digestates the default IPCC EF1 of 0.01 kg N2O-N per kg total N applied is used to estimate direct N2O emissions. For manure-based digestates the same EF as slurry is used (0.75% of N applied). Emissions from sewage sludge application to land are calculated following IPCC methodology (2006, equation 11.1). The calculation involves estimating the amount of N contained per dry matter unit of slu dge that is applied to land. Activity data are provided by Ricardo from a combination of the UK environment regulatory agencies and water companies. The N content is assumed to be 3.6% of the dry matter content. According to CEH (2017), in the UK 95% of sewage sludge is assumed to be applied as sludge cake and 5% as a liquid (ADAS, personal communication, December 2006), with no change across the time series. The data are disaggregated at the most at DA level, with the proportions on arable and grassland be ing derived from the BSFP from 2005. Uniform application rates across land are assumed per DA. Agriculture (CRF Sector 3) 5 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 369 For the inventory model we use the average RB209 value for the total N content of biosolids (4 digested cake, thermally dried, lime-stabilised and composted), assuming equal proportions of each, giving 3.7% on a DM basis. For the purposes of expressing the NH 3 emission factor as a %TAN applied, the TAN content is assumed to be 10% of the TN content (RB209) for sludge cake and 50% (assumed similar to li vestock slurry) for liquid sludge. The No data have currently been collated regarding proportional split in application to grassland and arable land, so a simplistic assumption is mad e that it is applied approximately in proportion to the ratio of improved grassland to arable land at DA level. Based on 2010 land area values (and used across the time series for simplicity) this gives a proportional application to improved grassland of 50%, 94%, 71% and 93% for England, Wales, Scotland and Northern Ireland, respectively, with the remainder to arable. We have updated sewage sludge data for 2019 with actual data and used 2019 data for 2021. For both sewage sludge and non-manure based digestate applied to land, the N 2O EF4 (mean and uncertainty) and EF 5 (uncertainty) were updated according to the IPCC 2019 refinement to the 2006 guidelines.
5.5.2.3.2 Manure-based digestate and other non-agricultural materials Application to agricultural land in GB wa s addressed according to Hulin et al. (2015 ). These Digested liquid sewage sludge, composted green manure, digested sludge cake, thermally dried sludge cake, lime -stabilised sludge and biosolids. The N 2O EFs for these Four categories of digestate applied to land are included depending on livestock manure, energy crops, food -waste and other organic residues, and for the purpose of the emission calculations each is treated individually (i.e. excludes and potential interactions that may arise through co-digestion). Emissions from digestate arising from the anaerobic digestion of livestock manures are included in the relevant livestock sector calculations. Emissions from spreading of digestate arising from th e anaerobic digestion of manures, food waste, energy crops and other organic residues are included in this sector. Material inputs to anaerobic digestion facilities are derived from the National Non-Food Crops Centre (most recently NNFCC, 2021), with estimated capacity and type of feedstock. Total N content of digestates is based on literature review (Tomlinson et al., 2019) giving mean values of 5.00, 3.97 and 3.35 kg t -1 for food-waste, energy crop and other organic residue based digestates, respectively, and it is assumed there is no trend across the time series. The TAN content of all digestate types is assumed as 80% of the total N content (RB209). Although co- digestion of two or more feedstocks is commonly practiced, for the purpose of the emission calculations each is treated individually. As with sewage sludge, we currently have no data relating to the proportion of digestate applied to grassland or arable land, so the same assumptions are applied (i.e. application in proportion to total land area as improved grassland or arable at DA level). Thus, proportion applied to improved grassland is assumed as 50, 94, 71 and 93% for England, Wales, Scotland and Northern Ireland, respectively, with the remainder to arable, and constant across the time series. Composted materials subsequently applied to land include green wastes, other organic materials (e.g. kitchen wastes) and mixed other materials (e.g. cardboard), with activity data for recent years sourced from government and local authority statistics and the Waste Data Interrogator returns system (Tomlinson et al., 2019). Emissions from the composting process are reported in the Waste sector. Emissions from the composting and subsequent land application of livestock manures are currently Not Estimated in the UK GHGI due to a lack of activity data; it is not a widespread practice and to date the UK farm survey data have not identified any activity data for use in the inventory. The EFs to estimate emissions of N 2O from dairy, sheep, pig, poultry and minor l ivestock manure spread to land (as a % of N applied) were derived from a large number of experiments

Agriculture (CRF Sector 3) 5 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 370 distributed across the UK also under Defra project AC0116 (Topp et al., in prep.). The resulting values slurry 0.7475, FYM and poultry manure 0.3635, for digestate is assumed to be the 5.5.2.4 Urine and dung deposited by grazing animals in the field Emissions are calculated a slightly modified IPCC methodology (equation 11.1), as different EFs are applied for urine and dung in t he case of cattle. Estimates of the times of the year when ruminant stock types were housed were made by Parsons and Williams (2015) in a module of the FBS in England. It is assumed that all excretion from grazing livestock is deposited on grassland. N excretion for cattle is partitioned to urine and dung N as described in Section 5.3.2.2, and the separate UK-specific values for EF3 for urine and dung are applied specifically for sheep grazing, EF3 for sheep excreta deposited to land is estimated by scaling down from cattle the ratio of EF 3 for excreta from sheep vs cat tle as exactly 50% of the CS values for cattle urine and dung. For swine, poultry, goats, deer and horses where behaviour of outdoor animals is quite different to that of cattle and sheep, the default value in IPCC (2019) EF3 is used, as this is regarded as the EF that is most representative of UK circumstances in the expert opinion of the UK Inventory Agency. The UK applies a CS N 2O EF for cattle urine and dung, based on measurements, but there are insufficient CS data for N 2O emissions from sheep excreta during grazing. According to of the value for cattle excreta. This is supported, for sheep urine, by information in the 2019 0.39% for sheep compared with 0.77% for cattle), while the EF for sheep dung contained therein is less than 50% of the value for cattle (0.04% for sheep compared with 0.13% for cattle). On the basis of this information, the UK has derived an N 2O EF for sheep urine and dung by halving the CS values for cattle urine and dung. We note that the resulting values (0.315% and 0.097% for sheep urine and dung, respectively) are closely comparable the revised values for sheep given in the 2019 Refinement to the 2006 IPCC Guidelines, and hence the UK considers that their use is justified and representative of UK circumstances. 5.5.2.5 Crop Residues returned to soils Direct N2O emissions from crop residues are estimated following IPCC (2006, equation 11.2) using the default value for EF1. However, a country-specific approach is taken to deriving the quantity of N returned in crop residues, based on UK -specific data for the harvest index and, where available, UK-specific data for N content of crop residues (Annex Tables A 3.3.13 and A 3.3.14). More specifically, the IPCC calculation involves the ratio of crop yield (DM) to total above-ground dry weight (DM harvest index, HI DM. The harvest index can also be defined with respect to nitrogen (N) as nitrogen harvest index (NHI).
The DM harvest index is the ratio of the primary crop DM yield of crop T over the sum of the primary crop DM yield (CropT) and the above ground biomass DM (eq. 4). The NHI is shown in eq. 5 and with data fo r the DM harvest index, AG DM(T) can be calculated by rearranging eq.5 to obtain the above ground residue per unit area (𝐴𝐺𝐷𝑀(𝑇)) (eq.6 and 7). HIDM = CropT / CropT + AGDM(T) (eq.4) HIN = (CropT ∗ CropN(T)) / (CropT ∗ CropN(T) + AGDM(T) ∗ NAG(T)) (eq.5) CropN(T) = fraction of N in the DM of cropT. AGDM(T) = CropT − (CropT ∗ HIDM )HIDM / HIDM (eq.6) AGDM(T) = (1 − HIDM ) ∗ CropT/ HIDM (eq.7)

Agriculture (CRF Sector 3) 5 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 371 The IPCC default values for the ratio of above to below ground biomass were used, except for crops not defined by the IPCC, e.g. sugar beet. These were evaluated by Williams and Goglio Estimates of the N returned to soil under cover crops were mad e from the NDICEA crop simulation model (van der Burgt et al., 2006), which was calibrated and tested in UK conditions N2O emissions from mineralisation of soil organic matter on land converted to Cropland more than 20 years ago are included in the Agricultural inventory (emissions from more recent land use change are included in the LULUCF inventory). Details are included in the LULUCF chapter (Section 6.3 Category 4B Cropland and in Annex 3). N2O emissions from mineralisation of soil organic matter as a result of Cropland Management activities are estimated from the change in soil carbon stocks due to Cro pland Management using a Tier 1 approach with the mineralised N calculated mineral soil carbon stock losses * (1/C:N ratio) where C/N is the IPCC default value of 15. The methodology used to assess change in soil carbon stocks due to Cropland Manage ment is described in Section 6.3 and Annex 3 and briefly consists of using a Tier 3 model described in section A 3.4.2 of the NIR annex. 5.5.2.7 Cultivation of histosols (organic soils) Direct N2O emissions from the cultivation of histosols are estimated following IPCC (2006, equation 11.2) using UK-specific data for the area of cultivated histosols. Areas are based on an estimate from a BEIS -funded research project (Evans et al., 2017), specified as cropland or intensive grassland (368.6 kha combined areas in 2021). IPCC Tier 2 EFs from the Peatland code report (Defra, UK - Science Search) are used for cropland and intensive grassland (see LULUCF chapter, Section 6.3 Category 4C Grassland). Annex section A 3.4.6 covers emissions from organic soils and EFs are listed in a supplementary Excel file ( see Supplementary file EFs UK inventory agriculture_2023 submission.xlsx) Updates to the deforestation areas on orga nic soils feed through into changes to the total cropland and intensive grassland areas on organic soils over time. 5.5.2.8 Atmospheric deposition of NOX and NH3 Indirect emissions of nitrous oxide (N2O) from the atmospheric deposition of ammonia (NH3) and oxides of nitrogen (NOX) are estimated according to IPCC (2006, equation 11.9) using a country-specific value for EF 4 (Pers. Anthony, 2021). The derived overall emission factor is similar to the recently revised IPCC (2019) default N 2O EF4 of 1.4±0.15%, for a ‘wet climate’ where annual rainfall exceeds potential evapotranspiration, based on an updated global database of measurements of emissions following applications of manufactured fertiliser nitrogen and organic manures (excluding urine and dung) to agricultural land ( IPCC 2019; EF, we note that the UK evidence was used to derive a value consistent with the value presented in the 2019 Refinement, and hence in our expert judgement to use the 2019 Refinement EF is the most representative EF option available to best reflect UK circumstances; we consider that applying that EF minimises the uncertainty in the UK Inventory for this source. Country-specific values were also applied for the fraction of N that is volatilised as NH 3 and NOx from inorganic fertiliser and organic (livestock manure, sewage sludge, digestate, grazing returns) N applications to land (FracGASF and FracGASM, respectively) derived directly from the combined ammonia and greenhouse gas inventory model for UK agriculture, using an N -flow approach (Webb and Misselbrook, 2004). UK-specific NH3 EF are used for inorganic fertiliser

Agriculture (CRF Sector 3) 5 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 372 and organic manure applications to land, as detailed in the UK Informative Inventory Report. FracGASF and Frac GASM values range between 0.03 -0.15; the NH 3 EFs are given in a supplementary excel file. NOx emissions from fertiliser, organic manure applications, grazing returns to grassland, and for crop residues are assumed to be a factor of 0.6 of the N 2O emissions estimated for each source, whereas those from applications to arable land are assumed to be a factor of 0.4 (see detail in the UK Informative Inventory Report). The method used corrects for the N content of manures used as fuel (poultry litter incineration) which are therefore not applied to land. Indirect emissions of nitrous oxide (N2O) from leaching and runoff are estimated according to IPCC (2006, equation 11.10) using the default value for EF5. The sources of N considered are synthetic fertiliser application, animal manures, digestates and sewage sludge applied to soils, excretal grazing returns (dung and urine), crop residues and mineralisation. A country-specific value for the proportion of N applied that is leached (Frac LEACH) is used for both inorganic fertiliser and manure application to grassland and excretal returns from grazing li vestock, based on the UPCYCLE model ( Pers. comm. : Anthony, 2021 ). For fertiliser and manure application to arable land, crop residues and sewage sludge the default IPCC (2006) FracLEACH value is used as this was supported by Cardenas et al. (2013 ) for UK c onditions. For mineralisation, the default IPCC (2006) value is also used.
The method used corrects for the N content of manures used as fuel (poultry litter incineration) which are not applied to land. For other organic sources applied to land, FracLEACH values of 10 and 30% of applied N are used for grassland and arable land, respectively, to estimate leached N based on Cardenas et al. (2013). In the case of NOx, the emission multiplier was set to 0.60 and 0.40 of direct emission from N application to grassland and arable land, respectively. In the case of swine and goats, the value was set to 0.60 of direct N2O emissions for outdoor pigs. Uncertainties and time-series consistency The uncertainty analysis in Annex 2 provides estimates of uncertainty per IPCC source The estimates of uncertainties in emissions were calculated using an Approach 2 method (Monte Carlo simulation) as described by the IPCC. The uncertainties in the estimates of crop areas were provided by the devolved administrations, and the uncertainties in estimates of fertiliser application rates to crops were calculated from the BSFP. Together these give estimates of fertiliser use. Estimates of the uncertainty in the amount of sewage applied to the land were omitted but will be included in further developments of the model. The uncertainties in the UK specific emission factors and model parameters were calculated from the data used to derive the emission factors. The UK inventory uncertainty calculations have been reviewed and updated by the UK sector experts within the 2023 submission; the analysis is now fully consistent with the methods applied in the UK inventory and uncertainty parameters will be ke pt under review for We note that the UK continues to apply the indirect N 2O EF 4 (mean and uncertainty parameters), EF5 (uncertainty bounds only) and the N 2O EF3 (mean and uncertainty, lower mean value and narrower uncertainty bounds) for poultry, deer, horses, pigs and goats according to the IPCC 2019 Refinement to the 2006 Guidelines, as they are regarded as more representative of UK circumstances based on the e xpert judgement of the UK Inventory

Agriculture (CRF Sector 3) 5 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 373 Emissions are calculated from a range of activity data and appropriate emission factors (see Annex 3). Emissions of nitrous oxide from the use of fertilisers are important in this source category. The annual consumption of synthetic fertiliser is estimated based on crop areas (crop area data reported annually by the Devolved Administrations) and fertiliser application rates (reported annually in the BSFP). These are both long running datasets and the compilers of the activity data strive to use consistent methods to produce the activity data. The time-series consistency of these activity data is very good due to the continuity in data provided. Source-specific QA/QC and verification This source category is covered by the general QA/QC procedures, which are discussed in All sources IEFs agree with the IPCC default value of 1% (inorganic and organic fertilisers, crop residues and mineralisation) except for pasture, range and paddock with 0.33%, histosols with 11.9 kg N ha-1, higher than the IPCC default values of 2% and 1% (the latter for sheep) and 8 kg N ha-1, respectively. Source-specific planned improvements Review methods and assumptions in grassland and cropland; including the estimates of fertiliser application rates from the BSFP; calculate N2O emissions from spreading of compost. Seek UK activity data or identify a suitable IPCC good practice gap -filling option, in order to address the minor gap in the UK GHGI estimates from the spreading of composted manures. Improve estimates of the urea content of the ‘other nitrogen’ compound fertiliser types. Emission factors and activity data will continue to be reviewed including the use of more detailed emission factors and activity data to improve emission estimates and allow estimation of the effect of future mitigation policies

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 374 Source-specific recalculations Details of and justifications for recalculations to activity data and to emission factors are given in the tables below.
Category Source Name 1990 2020 1990 2020 3.D.1.1 Direct N2O Emissions from Managed Inorganic N fertilisers 20.03 10.91 20.14 10.88 kt Improved methodology to estimate fertiliser application rates; Updates to the quantity of Di-Ammonium Phosphate applied to crops based on improved methodology; Update of provisional surveyed fertiliser rate for Northern Ireland in 2020; As Grassland plus revision of the uptake of ‘placed’ N fertiliser as a mitigation option and minor changes to 3.D.1.2.a Direct N2O Emissions from Managed Organic N Fertilisers – Animal 4.60 3.88 4.63 3.90 kt Emissions from spreading affected by the changes detailed for ‘Manure Nitrous Oxide emissions’ plus spreading mitigation uptake for cattle and pig slurry updated; Introduced NI-specific data for proportion of cattle slurry and FYM applied to 3.D.1.2.c Direct N2O Emissions from Managed Organic N Fertilisers - Other Organic Fertilisers Applied to Soils 0.00 1.00 0.00 1.07 kt Updated amounts of manure and non-manure based digestate 3.D.1.3 Direct N2O Emissions from Managed Urine and Dung Deposited by 2.948 2.374 2.952 2.379 kt Emissions from urine and dung affected by the changes detailed for ‘Manure Nitrous Oxide emissions’ affecting N

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 375 Category Source Name 1990 2020 1990 2020 3.D.1.4 Direct N2O Emissions from Managed 5.19 5.47 5.34 5.10 kt Updates to crop yield estimates and fertiliser N activity data used 3.D.1.5 Mineralisation/Immobilization Associated with Loss/Gain of Soil Organic Matter 0.61115 1.30359 0.61116 1.30387 kt Minor changes to the area of cropland on organic soil 3.D.1.6 Direct N2O Emissions from Managed Cultivation of Organic Soils 5.68 5.37 7.31 6.93 kt Minor changes to organic soil areas and adjustment to peatland restoration data for intensive grassland in England; Emission factors applied to cropland and intensive grassland have been 3.D.2.1 Indirect N2O Emissions From Managed Soils – Atmospheric Deposition 3.14 2.56 3.01 2.59 kt As ‘Direct N2O Emissions from Managed Soils’ plus revisions to NOx ratios for the poultry sector 3.D.2.2 Indirect N2O Emissions From Managed Soils - Nitrogen Leaching and Run-off 6.34 5.32 6.38 5.19 kt As ‘Direct N2O Emissions from Managed Soils’ plus adjustment to the FracLeach value for goats, deer and horses to ensure consistency across all sectors

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 376 Category Source Name 1990 2020 1990 2020 Units Comment/Justification 3.D.1.1 Direct N2O Emissions from Managed Inorganic N fertilisers 0.00810 0.00730 0.00815 0.00731 kg N2O- 3.D.1.2.a Direct N2O Emissions from Managed Organic N Fertilisers – Animal 0.00609 0.00606 0.00610 0.00607 kg N2O- 3.D.1.2.c Direct N2O Emissions from Managed Organic N Fertilisers - Other Organic Fertilisers Applied to Soils 0 0.0094 0.0075 0.0093 kg N2O- 3.D.1.3 Direct N2O Emissions from Managed Urine and Dung Deposited by 0.003331 0.003299 0.003332 0.003301 kg N2O- 3.D.1.6 Direct N2O Emissions from Managed Cultivation of Organic Soils

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 377 This source is not relevant in the UK. Source included Method Emission Gases Reported CH4, N2O, NOx, CO, NMVOC, SO2 Key Categories None identified Completeness No known omissions. A general assessment of completeness for the inventory is The National Atmospheric Emissions Inventory reports emissions from field burning under the category agricultural incineration. The estimates are derived from emission factors calculated according to IPCC (1997) and from USEPA (1997). The estimates of the masses of residue burnt of barley, oats, wheat and linseed are based on crop production data from DEFRA (England & Wales), The Scottish Government (Scotland) and DAERA (Northern Ireland), a UK -specific harvest index approach to derive residue amounts (Williams and Goglio, 2017) and data on the fraction of crop residues burnt ( MAFF, 1995; ADAS, 1995). Field burning ceased in 1993 in England and Wales. Burning in Scotland and Northern Ireland is considered negligible, so no estimates are reported from 1993 onwards. The carbon dioxide emissions are not estimated because these are part of the annual Uncertainties and time-series consistency The uncertainty analysis in Annex 2 provides estimates of uncertainty per IPCC source category. The UK inventory uncertainty calculations have been reviewed and updated by the

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 378 UK sector experts within the 2023 submission; t he analysis is now fully consistent with the methods applied in the UK inventory and uncertainty parameters will be kept under review for Field burning ceased in 1993, and emissions are reported as NO after this date. Source-specific QA/QC and verification This source category is covered by the general QA/QC procedures, which are discussed in Source-specific recalculations No recalculations were carried out in this sector. Source-specific planned improvements Emissions sources Source included Method Emission Key Categories None identified Completeness A general assessment of completeness for the inventory is Adjustment to the liming areas and rates for NI and introduction of 3-year rolling average for all DAs 5.8.1.1 Source category significance, trends and drivers Total CO2 emissions from liming in 2021 were 1175 kt CO 2. Emissions in 2021 were 15.6% CO2 emissions due to the application of lime and related compounds are estimated using the Tier 1 IPCC (2006) methodology. For calcium carbonate (limestone, chalk and sugar beet lime - LimeX) an emission factor of 120 tC/kt applied is used, and for dolomite application, 130 tC/kt. UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 379 These factors are based on the stoichiometry of the CO2 loss from the carbonates and assume pure limestone/chalk and dolomite. Liming activity data (% area limed and application rate to three land use ‘all tillage’, 1990 and 1991 were assumed to be the same as for 1992. The % area limed and application rate of lime in Northern Ireland was assumed to be the same as that for Scotland by land use type.
For each of the liming types in i) ground limestone, ii) ground chalk, iii) magnesian limestone, iv) sugar beet lime, iv) other), the application rate and % area limed were multiplied by the area of ‘all tillage’, ‘grass under 5 years old’ and ‘grass 5 years and over’ to derive the total limestone and dolomite applied for each Devolved Administration. The ‘other’ category in B SFP is made up of Ag slag, calcified pelleted limestone, Calcifert, granules, Humistar, lime slag, screed lime ( Defra, pers. comm. ); the majority of these are CaCO3 based limes and thus were included in the activity data for limestone. Limex is assumed to have 46% CaCO3 content (British Sugar, Chemical Safety Data; Median of LimeX45 (45%) and LimeX70 (52%) CaCO3 content). Uncertainties and time-series consistency Uncertainty in both the activity data and emission factor are judged to be low. The main source of uncertainty in the estimates is caused by non -publication of some activity data due to commercial restrictions although these are not judged to be very significant. There is good time series cons istency as there has been continuity in the published data Source-specific QA/QC and verification This source category is covered by the general QA/QC procedures, which are discussed in

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 380 Source-specific recalculations Category Source Name 1990 2020 1990 2020 Units Comment/Justification 3G CO2 from Limestone and 1014.03 947.83 1016.42 1117.28 kt Adjustment to the liming areas and rates for NI; Introduction of 3 year rolling average for all DAs; Minor changes to arable crop areas for some years

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 381 Source-specific planned improvements Emission factors and activity data will continue to be reviewed when new data are available Emissions sources Source included Method Emission Key Categories None identified Completeness A general assessment of completeness for the inventory is Revisions to application rates of urea-based fertiliser as part of the improved methodology adopted in the grass and arable 5.9.1.1 Source category significance, trends and drivers Total CO2 emissions from urea application in 2021 were 252 kt CO2. Emissions in 2021 were The annual amount of fertiliser as urea, alone or as part of urea ammonium nitrate (UAN), used in kt N was estimated from the BSFP (for England, Wales and Scotland) and the Northern Ireland Fertiliser Supply statistics. Both fertilisers are applied to grassland and cropland in the UK. It was assumed that 35% of UAN was urea. The EF used was the IPCC (2006) default value of 0.2 tonne of C tonnes of urea-1, and emission estimates were made using IPCC Tier Uncertainties and time-series consistency The uncertainty analysis in Annex 2 provides estimates of uncertainty per IPCC source The UK inventory uncertainty calculations have been reviewed and updated by the UK sector experts within the 2023 submission; the analysis is now fully consistent with the methods applied in the UK inventory and u ncertainty parameters will be kept under review for The same data source is used for the entire time series to ensure consistency. UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 382 Source-specific QA/QC and verification This source category is covered by the general QA/QC procedures, which are discussed in Source-specific recalculations Details of and justifications for recalculations to activity data and to emission factors are given

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 383 Category Source Name 1990 2020 1990 2020 Units Comment/Justification 3H CO2 from Urea Application 326.88 233.59 292.95 233.63 kt Revisions to application rates of urea -based fertiliser as part of the improved methodology adopted in the grass and arable sectors; Minor changes to arable crop areas

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 384 Source-specific planned improvements Emission factors and activity data will continue to be reviewed when new data are available. Emissions sources 3A: Enteric Fermentation 3F: Field Burning of Agricultural Residues In the CRF, all UK overseas territories and crown dependencies emissions data are reported in sector 3J. Emission Factors Default EFs (OTs), UK implied EFs (CDs) Key Categories None identified Completeness Emissions are not estimated from 3G Liming for Bermuda, Cayman Islands and the Falklands, from 3H Urea application for Bermuda and the Falklands, and from 3F Field Burning of Agricultural Residues for any OT. Livestock and crop production occur in all of the UK overseas territories (OTs) and crown dependencies (CDs), resulting in emissions from categories 3A, 3B and 3D for all OTs and CDs. Agricultural GHG emissions from OTs and CDs combined made up less than 1% of the total UK agricultural emissions in 2021. Note that no agricultural activities oc cur in Gibraltar, so emissions and activity data are zero for Gibraltar for all agriculture sector sources. 5.10.2.1 Emissions from livestock The CDs have similar farming systems to the mainland UK and are located nearby with a similar climate. Due to this similarity, emissions for CDs are calculated by applying implied EFs calculated from the UK GHGI to data on livestock numbers for CDs aggregated to a basic classification. The implied EFs are calculated for each year, so that the implied EF can vary across the time series. Tables of animal numbers used in calculations are presented in Annex For OTs, emissions from livestock are calculated using Tier 1 methodology from the IPCC 2006 Guidelines (2019 Refinement for deer enteric fermentation and wastes), applying default EFs for the appropriate geographic region and climate type to the number of livestock reported. For both CDs and OTs, data on livestock numbers was provided by local contacts. UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 385 5.10.2.2 Emissions from 3D Agricultural Soils For the CDs, estimates of emissions from agricultural soils for all sub -categories were made by applying UK GHGI implied EFs to animal numbers (for livestock manure -related activities) and land areas of cropland and grassland (for non-manure fertilisers and emissions related to loss of soil carbon).
For OTs, the Tier 1 methodology from the 2006 IPCC Guidelines was applied to calculate emissions from agricultural soils. Livestock numbers, mineral fertiliser application and crop production data were provided from each of the OTs or sourced from FAO; these data can be found in Annex 3.6. Emission factors taken from the 2006 IPCC guidelines were applied to all activity data from OTs. In the Falklands, according to local expert judgement no synthetic fertilisers are applied, so emissions from this source are not estimated there. In the Falklands, despite there being a very large area of grassland histosols, N 2O emissions from managed histosols are only reported for cropland areas. The reason for this is that information from local experts indicates that grasslands are unmanaged (i.e. no fertilisation, liming, drainage or cultivation) and livestock density is low, so these soils are not likely to be a source of N2O emissions. The UK understands man aged organic soils to be present only in the Falkland Islands and the Isle of Man, and absent from all other CDs and OTs. 5.10.2.3 Emissions from other agriculture categories For the CDs, emissions 3F Field Burning of Agricultural Residues and 3H Urea Application are estimated in the same way as emissions from 3D Agricultural soils, by applying implied EFs from the UK GHGI to the land area of cropland (for both field burning and urea application) and grassland (for urea application only). Emissions from 3G Liming a re calculated using the default 2006 IPCC EF of 0.12 kg C/kg limestone, applied to data on the quantity of limestone For the OTs, no emissions were estimated for categories 3F Field Burning of Agricultural Residues due to lack of available activity data. Emissions were not estimated from 3G Liming due to local experts indicating the activities do not occur. Emissions from 3H Urea Application are estimated for Cayman Islands only from 2014. Total agricultural land area and emissions

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 386 dependencies and all other overseas territories Territory Category 1990 1995 2000 2005 2010 2015 2018 2019 2020 2021 UK Cropland area (kha) 5430 5386 5297 5148 4957 4899 4818 4813 4792 4772 Grassland area (kha) 10,281 10,160 9,808 10,065 9,980 9,880 10,072 10,193 10,042 9,965 Isle of Man Cropland area (kha) 50.49 50.29 50.04 49.79 49.54 49.54 49.54 49.54 49.54 49.54 Grassland area (kha) 45.15 45.31 45.06 44.80 44.57 45.45 46.09 46.15 46.08 46.18 3F emissions (ktCO2e) 0.222 NO NO NO NO NO NO NO NO NO 3G emissions (ktCO2e) 0.592 0.565 0.571 0.574 0.570 0.531 0.531 0.531 0.531 0.531 3H emissions (ktCO2e) 0.0950 0.0446 0.0387 0.0594 0.0727 0.0760 0.0654 0.0630 0.0493 0.0479 Cropland area (kha) 0.566 0.566 0.566 0.566 0.793 0.793 0.793 0.793 0.793 0.793 Grassland area (kha) 1215 1215 1215 1215 1215 1215 1215 1215 1215 1215 3F emissions (ktCO2e) NE NE NE NE NE NE NE NE NE NE 3G emissions (ktCO2e) NO NO NO NO NO NO NO NO NO NO 3H emissions (ktCO2e) NE NE NE NE NE NE NE NE NE NE Cropland area (kha) 6.86 7.03 6.62 5.90 6.34 5.82 5.79 5.81 5.84 5.84 Grassland area (kha) 4.83 4.66 4.84 5.16 4.51 5.11 5.11 5.08 5.04 5.03 3F emissions (ktC2e) 0.286 NO NO NO NO NO NO NO NO NO 3G emissions (ktCO2e) 0.157 0.157 0.158 0.152 0.145 0.140 0.140 0.140 0.140 0.140 3H emissions (ktCO2e) 0.122 0.063 0.051 0.070 0.093 0.108 0.110 0.108 0.083 0.083 0.338 0.740 0.740 0.740 0.740 0.740 0.740 0.740 0.740 0.740 Grassland area (kha) NO NO NO NO NO NO NO NO NO NO 3F emissions (ktCO2e) NE NE NE NE NE NE NE NE NE NE 3G emissions (ktCO2e) NO NO NO NO NO NO NO NO NO NO 3H emissions (ktCO2e) NE NE NE NE NE 0.000349 0.000830 0.000735 0.000730 0.000730

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 387 To provide an indication of emissions reported as NE for 3F Field Burning and 3H Urea Application, cropland area for the OTs were calculated as a percentage of UK cropland area. Cropland area in the Falkland Islands does not exceed 0.002% of UK cropland area, as is the case for Bermuda and the Cayman Islands. The magnitude of emissions currently not estimated is therefore below the threshold of significance. Whilst grassland area in the Falklands Islands is a sizeable proportion of UK grassland area at 12.1%, local contacts indicate that liming does not occur, and that synthetic fertiliser (including urea) application is minimal. Uncertainties and time-series consistency There is incomplete activity data available for several sub -categories, including field burning activity, crop production, and application of synthetic fertiliser, liming and urea application. • Livestock statistics are not annually collected for all livestock types in all the OTs and CDs, so in some cases extrapolation was necessary, such as for non -cattle livestock for Jersey and all livestock types for Bermuda. • For synthetic fertiliser application, in the Cayman Islands there is no data available before 2010, so this is extrapolated backwards based on an average. In Bermuda, only a single value is available for the whole time series, which has been assumed to remain • For emissions from crop residues, no data is available for the Falkland Islands so this source is not estimated. For Bermuda, crop production data is sourced from FAO up to year 2016 but is not available for later years so 2016 values have been extrapolated. • For the CDs, data on application of limestone was compiled until 2015 but is not now available, so 2015 values have since been extrapolated. • Due to lack of activity data for any year, emissions are not estimated from 3G Liming for Bermuda, from 3H Urea application for Bermuda and the Falklands, and from 3F Field Burning of Agricultural Residues for any OT.
IPCC Tier 1 default factors from the 2006 Guidelines have been used to estimate emissions for the OTs, using the closest regional values matching the climate and production systems. However, this does introduce uncertainty as local geography, livestock breeds and production practices may differ. A similar uncertainty in CDs emissions arises from use of UK GHGI implied emission factors because local production practices may differ significantly from the UK average. However, there is generally a lack of available data and resource to support using higher-tier methods or developing local-specific EFs. Due to the proportionally small contribution of OTs and CDs to the national inventory, the UK only periodically aligns the CD emission factors with UK emission factors (currently the values from the 2019 submission are used), and for simplicity the UK present all OT and CD agriculture data in the CRF against 3J. The UK is considering changes to the institutional arrangements to make the process of updating the UK GHGI IEFs more robust in the future, to apply to activity data in the CDs. Improvements could be made to the method to update these IEFs regularly, instead of maintaining constant IEFs across the time series. It has been added to the improvement plan to discuss the changes to the institutional structure to make it more feasible to fully integrate emissions from the OTs and CDs and other data, into the appropriate CRF categories, rather than having emissions reported under 3J. UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 388 The Inventory Agency is consulting with stakeholders to seek more complete activity data for the OTs and CDs where this is currently lacking, including updated livestock, fertiliser and crop production data from OTs, and liming data from the CDs. Further, the Inventory Agency will review the assumptions, based on local expert judgement, that no synthetic fertiliser, limestone or urea is applied in the Falklands. Finally, there is a longer-term research project into organic soils and emissions in the Falkland Islands, the results of which will inform future inventory improvements once completed. The UK agriculture inventory has a documented QA/QC plan covering the annual compilation of the inventory by the contracted consortium (led by Rothamsted Research) addressing governance, data management, quality control (procedures and checks) and quality assurance activities. The organisational roles and responsibilities of the delivery team and government stakehold ers are described. The inventory compilation, reporting, review and improvement cycle for an annual submission to UNFCCC and UNECE is outlined with an overview of the key QC and QA activities at different stages in the cycle, including the timings for the annual compilation cycle and details of source-specific quality checks to be performed on the incoming data, the calculation models and the data validation checks on model outputs. The QA/QC plan is subject to annual review. The agriculture inventory data quality objectives are based on the inventory quality objectives of Transparency, Accuracy, Consistency, Comparability and Completeness (TACCC) as set out in the IPCC national inventory reporting guidelines and clear statements are provided as to how these are to be met. Security, scope and timeliness of data supply are addressed, with Data Supply Agreements being developed with suppliers of key input data. Procedures are in place for the management of confidential data (e.g. farm holding level data) and for data storage, back-up and archiving. During the finalisation of the agriculture “master” dataset and the integration of these data into the wider UK inventory data for onwards submission to the UNFCCC and UNECE, there are iterative quality checks perfo rmed by the Inventory Agency (under contract to DESNZ) to highlight any data anomalies, recalculations and inventory trends compared against previous inventory submissions. There is then a period of dialogue and clarification of the agriculture data and supporting information is provided to the Inventory Agency where applicable. Peer and bilateral reviews of the agriculture inventory have been conducted, and the revised methodological approaches introduced in the 2018 submission through the Defra GHG improvement programme were reviewed by an international Research Expert Group (including several IPCC Inventory Review Experts) as part of the programme. Furthermore, the UK underwent an In-Country Review in 2019 and recommendations for improving the NIR have been taken into account in this submission. Further details of the QAQC of the UK agriculture model are provided in the model description

Land-Use, Land-Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 389 6 Land-Use, Land-Use Change and emissions of greenhouse gases and precursors (CO2, CH4, N2O, NOx and CO) from Land Use, Land-Use Change and Forestry (LULUCF) activities. Removals of carbon dioxide are conventionally presented as negative quantities. Total LULUCF - 11.2 1.3 1.2 -2.3 -2.9 A. Forest Land 11 (CO2) 15% -13.4 -17.7 -17.6 -0.2 -0.5 B. Cropland 10 (CO2), 20% 15.2 13.4 13.4 -1.7 -1.7 C. Grassland 23 (CH4), 31 (CO2) 15% 2.3 0.3 0.3 -0.6 -0.7 D. Wetlands 26 (CH4) 40% 3.0 3.0 3.0 0.2 0.1 E. Settlements 22 (CO2) 40% 5.8 4.1 4.1 0.0 -0.2 2All values for uncertainty refer to those associated with the latest year CO2 emissions with the exception of Indirect N2O where the value is for latest year N2O. 3The values given are the difference in 1990 or 20 20 emissions/removals from the data reported in the previous UK GHGI submission using AR5 GWP values (without feedbacks). The summary analysis of the trends in greenhouse gas emissions from the LULUCF sector is provided in Section 2. The methodological differences since the previous UK GHGI submission are explained in this chapter . This information is presented in the last cell of the tables at the start of each section providing an overview of each of the LULUCF categories (Major improvements since last submission). The LULUCF sector covers emissions and removals of direct greenhouse gases under seven categories, of which Forest Land (4A) and Harvested Wood Products (4G) are net sinks, and 6.1) as well as indirect N 2O emissions.
The UK does not report any emissions or removals from the Other Land (4F) category. The LULUCF sector is the only sector within the national greenhouse gas inventory which reports both sources and sinks. The net sink is provided by removals from carbon stock gains in above-ground and below-ground biomass, soils and harvested wood products exceeding

Land-Use, Land-Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 390 emissions from carbon stock losses and GHG emissions (CO2, CH4 and N2O) from LULUCF

Land-Use, Land-Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 391 The land use transition matrix The areas used for the three UK CRF submissions are based on the Standard Area Measurement to mean high water is used for th e total area of the UK (24 ,438.5 kha) (Office for National Statistics 2017) and the land areas reported in national statistics for the OTs and • Falkland 1,217.3 kha All areas are assigned to one of the LULUCF land use categories (Forest Land, Cropland, Grassland, Wetland, Settlements, Other) . All land use is considered to be managed , apart from a small area of wetland (0.12 kha of sea) in Jersey which has been used for land The UK uses Approach 2 (IPCC 2006) for the representation of land use areas in the inventory. The UK estimates land use change using a Bayesian data assimilation appro ach (Annex 3.4.2.1). This constrains estimates of gross land-use change with national-scale census data, whilst retaining the detailed information available from other land-use data sources. The data sources are compiled at the individual country level (England, Scotland, Wales and Northern Ireland) and results are combined to give UK totals. CRF Reporter) and the CRF carbon stock reporting tables, it is assumed for the UK o The total areas of land use categories from recent reports (2015 or 2021) are the most o The areas of LUC used for carbon stock changes are the most consistent sources of Source dataset Relevant components of Forest Land National Forest Inventory (NFI) (GB)1 and Northern Ireland Woodland Base Annual afforestation and deforestation Cropland UK Agricultural Census (Defra, DAERA, Scottish Government, Welsh Grassland ONS Standard Area Measurement land area – area of other categories3 Wetlands ONS Standard Area Measurement UK Directory of Mines and Quarries, Google Earth imagery and Growing

Land-Use, Land-Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 392 Source dataset Relevant components of Media Association data (peat extraction Peat condition maps (Evans et al. 2017), Growing Media Association and Peatland Action (2020) (peatland Settlements Land Cover Map 2015 (UKCEH 2015) Urban land cover class Other Land Land Cover Map 2015 (UKCEH 2015) Inland rock, supra-littoral 1 Forestry Commission (2017) “Tree cover outside woodland in Great Britain report” land use matrix. The initial land use areas in 2015 are also the final land use areas in 2014. These are used with the transitions to and fr om each land use category in 2014 (see the individual land use category Sections 6.2 to 6.6 for details) to ca lculate the initial land use areas in 2014 and area of each category that does not undergo any change. This approach is used to calculate the initial and final land use areas back in time to 1990, and forward in time from 2015. Forest Land is the exception- the area in the latest inventory year is considered to be the most reliable and the initial and final areas are calculated back in time from that point. Land cover surveys and agricultur al land statistics are used to compile annual land -use change matrices for the OTs and CDs. Information on these data sources is given in Annex Gibraltar’s land area is all categorised as Settlement remaining Settlement, so all other areas 6-4. Total areas in each year summed across all LULUCF categories may not equal the total land area in some years because of small rounding differences.
Land-Use, Land-Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 393 1990 3086.7 0.0 0.3 0.0 0.7 5376.2 6.3 63.3 0.0 2.6 14022.2 40.8 66.8 0.0 8.6 953.7 1710.4 1.0 0.4 1.8 421.3 1991 3133.8 0.0 0.3 0.0 0.7 5368.3 3.0 71.3 0.0 0.8 13987.4 23.5 68.5 0.9 7.4 953.7 1718.7 0.9 0.8 2.0 421.3 1992 3160.3 0.0 0.3 0.0 0.6 5367.0 2.9 66.4 0.0 1.5 13960.7 24.2 67.9 0.0 8.2 954.6 1724.8 0.4 0.5 1.9 421.3 1993 3186.7 0.0 0.3 0.0 0.6 5359.7 4.0 68.9 0.0 2.8 13929.9 24.2 66.4 0.0 8.8 954.6 1732.2 0.4 0.5 2.0 421.3 1994 3214.3 0.0 0.3 0.0 0.6 5353.8 3.6 68.1 0.0 1.2 13900.7 29.1 65.8 0.0 5.5 954.6 1740.4 1.1 0.3 2.6 421.3 1995 3247.2 0.0 0.3 0.0 0.6 5337.2 4.3 74.9 0.0 3.5 13877.1 24.4 61.6 0.3 8.3 954.6 1745.4 0.7 0.3 1.4 421.3 1996 3275.6 0.0 0.3 0.0 0.6 5322.6 3.7 70.7 0.0 2.2 13863.4 24.3 61.8 0.0 4.3 954.9 1754.3 0.6 0.6 2.2 421.3 1997 3303.0 0.0 0.4 0.0 0.7 5311.9 3.4 66.9 0.0 2.8 13848.1 25.9 58.2 0.0 4.4 954.9 1758.5 0.8 0.7 1.3 421.3 1998 3332.2 0.0 0.3 0.0 0.7 5302.7 3.0 63.6 0.0 1.5 13830.7 25.8 57.6 0.0 2.6 954.9 1763.5 0.5 0.6 1.7 421.3 1999 3360.4 0.0 0.3 0.0 0.8 5294.8 4.6 60.8 0.0 0.8 13816.1 24.1 53.4 0.0 2.7 954.9 1763.8 0.8 0.6 3.0 421.3 2000 3386.6 0.0 2.6 0.3 0.3 5262.5 2.7 81.8 0.0 1.8 13804.0 26.5 46.5 0.0 3.2 955.0 1765.3 0.8 0.1 1.9 421.3 2001 3413.0 0.0 3.1 0.3 0.3 5228.1 2.7 77.4 0.3 0.6 13817.3 19.2 51.3 0.0 2.6 955.3 1766.2 1.1 0.7 2.5 421.3 2002 3432.7 0.0 2.7 0.3 0.3 5195.0 2.7 81.0 0.3 1.1 13834.2 19.1 44.9 0.0 2.2 955.9 1767.0 0.8 0.3 1.5 421.3 2003 3451.1 0.0 3.1 0.3 0.6 5157.8 3.2 77.7 0.3 1.3 13851.5 17.1 48.4 0.2 2.3 956.5 1767.5 0.4 0.2 2.4 421.3 2004 3468.2 0.0 2.2 0.3 1.0 5131.7 2.4 71.1 0.3 1.0 13864.8 13.5 53.4 0.2 2.9 957.3 1769.2 0.8 0.2 1.6 421.3 2005 3481.1 0.0 2.4 0.3 0.9 5109.5 1.4 72.6 0.3 1.6 13874.4 12.4 49.6 0.2 3.0 958.2 1771.4 0.6 0.3 1.6 421.3

Land-Use, Land-Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 394 2006 3492.9 0.0 2.0 0.3 0.3 5058.8 3.6 95.1 0.3 1.7 13886.2 11.5 50.0 0.1 3.3 959.0 1774.3 0.8 0.5 1.3 421.3 2007 3504.8 0.0 2.8 0.5 0.7 5022.0 1.7 84.3 0.3 1.0 13917.3 10.1 54.2 0.1 2.9 959.6 1777.0 0.7 0.4 1.5 421.3 2008 3513.9 0.0 2.5 0.5 0.6 4988.3 1.2 86.0 0.3 0.9 13943.4 9.0 50.4 0.2 3.0 960.4 1779.0 0.2 0.5 1.9 421.3 2009 3520.7 0.0 2.6 0.5 0.5 4960.4 0.3 77.6 0.3 0.5 13974.6 8.7 48.6 0.1 1.9 961.3 1781.1 0.0 0.7 1.6 421.3 2010 3525.8 0.0 2.6 0.5 1.0 4920.2 1.3 85.8 0.3 2.2 13994.6 10.8 49.2 0.1 1.8 962.1 1781.8 0.5 0.2 1.4 421.3 2011 3535.1 0.0 2.0 0.5 0.9 4903.1 1.5 63.9 0.3 0.8 14011.0 15.4 55.4 0.0 2.5 962.9 1783.9 0.8 0.3 1.8 421.3 2012 3549.6 0.0 1.9 0.5 0.8 4889.0 1.4 67.7 0.3 0.4 14004.5 14.7 56.2 0.7 2.6 963.7 1785.1 0.9 0.2 1.9 421.3 2013 3563.5 0.0 1.9 0.3 0.8 4875.2 2.0 67.2 0.3 0.9 14005.2 12.8 56.3 0.0 1.7 965.1 1786.1 0.3 0.2 2.3 421.3 2014 3575.7 0.0 2.1 0.1 0.6 4859.6 1.4 69.1 0.3 1.4 14010.5 10.0 53.6 0.0 2.4 965.7 1787.2 0.3 0.2 1.7 421.3 2015 3583.0 0.0 1.4 2.3 0.8 4853.5 0.2 58.6 0.3 0.8 14018.0 6.6 56.2 0.0 2.7 966.1 1788.8 0.3 0.5 2.0 421.3 2016 3586.3 0.0 1.5 0.4 1.8 4825.5 0.7 82.2 0.3 1.6 14015.9 5.5 56.3 0.1 2.2 968.7 1790.7 0.3 0.0 2.1 421.3 2017 3589.6 0.0 1.4 0.3 1.4 4813.3 0.7 66.2 0.3 1.4 14035.7 7.7 55.3 0.0 3.0 969.4 1794.2 0.2 0.4 1.5 421.3 2018 3593.8 0.0 1.3 1.5 1.7 4782.4 1.9 81.2 0.3 3.3 14043.4 10.3 46.1 0.0 5.0 970.0 1797.4 0.4 0.1 2.1 421.3 2019 3601.2 0.0 1.1 2.7 1.4 4769.1 1.1 56.5 0.3 1.5 14058.8 12.0 53.5 0.0 3.6 971.8 1803.4 0.6 0.5 2.9 421.3 2020 3611.7 0.0 1.3 0.7 1.1 4753.0 0.7 65.0 0.3 4.2 14053.1 11.8 49.5 0.0 4.9 974.8 1806.9 0.9 0.2 1.9 421.3 2021 3622.0 0.0 1.4 0.6 1.1 4732.4 0.7 65.1 0.3 4.2 14054.9 12.1 49.4 0.0 4.9 975.8 1814.0 0.9 0.2 1.9 421.3

Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 395 Emissions sources 4A Forest carbon stock change 4(I) Direct nitrous oxide (N2O) emissions from nitrogen (N) 4(II) Emissions and removals from drainage and rewetting and other management of organic and mineral soils 4(III) Direct nitrous oxide (N2O) emissions from nitrogen (N) mineralization/immobilization associated with loss/gain of soil organic matter resulting from change of land use or Methods T3 for carbon stock changes, T2 for direct CO2 and CH4 and Emission Factors Country-specific for T3 methods Key Categories 4A: Forest land - CO2 (L1, L2, T1, T2), N2O (L2) Revision of assumed planting on organic soils to adjust for deforestation in all countries and pre-1900 planting on organic soils in Northern Ireland. Revision of Emission Factor for Particulate Organic Carbon (POC) losses from organic soils. This section describes LULUCF emissions and removals from Forest Land in the UK. A description of LULUCF emissions and removals from the OTs and CDs is given in Section Forest Land includes carbon stock gains and losses and GHG emissions from forest management and overall is the biggest net sink in the UK. All UK forests are temperate and about 74% of these have been planted since 1921 on land that had not been forested for many The UK reports carbon stock changes in all forests.
Forest surveys have been intermittent in the UK and to date there has been no network of permanent sample plots suit able for constructing a GHG inventory. Consequently, estimates of carbon stock gains and losses for biomass and soils are modelled based on planting history, assessed tree age class area distributions and productivity (yield class) estimates, and assumptions over approaches to forest management. Forest carbon stock changes and fluxes are modelled by CARBINE, the Forest Research forest carbon stock and carbon balance model (described in Annex 3.4.1). CARBINE takes account of the effects of forest management on carbon stocks, and also calculates the carbon stocks in the Harvested Wood Products pool. Carbon stock changes resulting from afforestation on Cropland, Grassland and Settlement on both mineral and organic soils are calculated. Conversion of Other Land to Forest Land does not occur in the UK. The reported forest area and carbon stock changes take account of losses of forest land converted to other land use categories (deforestation) and the associated carbon stock changes and emissions and removals are t hen estimated and reported under the category concerned. Associated direct N 2O emissions from N mineralization are reported

Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 396 In the UK inorganic nitrogen fertilisers are only applied to forest when absolutely necessary. This occurs during the first rotation on ‘poor’ soils, such as reclaimed slag heaps, impoverished brown field sites and upland organic soils, hence N fertilisation is assumed for all areas of Settlements converted to Forest Land and Grassland converted to Forest Land on or ganic fertilisers are not generally applied to native woodlands, mature forests or re-planted forests in Drainage of forest land occurs in UK forests planted on certain soil types. It is assumed that all forests planted on organic soils are drained prior to planting. Forests planted on mineral or organo-mineral soils which have slow natural drainage and are prone to waterlogging are also assumed to be artificially drained. CO2 emissions from drainage are included with carbon stock Rewetting of forests on organic soils results in a land use change and emissions are reported Controlled burning of forest land (for example for habitat management) does not take place in the UK. Wildfires do occur but the activity data are not sufficient to split reporting between 4.A.1 and 4.A.2. Therefore emissions of greenhouse gases from wildfires are all reported under 4.A.1 Information on approaches used for representing land areas and on land use databases used for the inventory preparation The agencies responsible for forests in the UK are the Forestry Commission (England), Scottish Forestry and Forest and Land Scotland, Natural Resources Wales and the Northern Ireland Forest Service. Areas of forest planted annually are published in Forest ry Statistics87 and a detailed breakdown (by forest type and management) is used as input to the CARBINE model, supplemented by information from the National Forest Inventory (NFI) field survey and the Northern Ireland Woodland Register . The allocation of land-use change from other land use categories is based on the proportional changes in the land-use change matrices from the data assimilation of multiple land -use data sources (see Section 6.3 and Annex 3.4). More information on the stratification of the UK forest area can be found in the UK National Forestry The area of forests on organic soils in the UK was based on peatland extent and c ondition mapping outputs from the BEIS -funded project to implement the 2013 IPCC Wetlands Supplement (Evans et al. 2017). These have been updated in this submission (see Annex A Land-use definitions and the classification system used and their correspondence to the LULUCF categories The UK uses the following definition of forest for reporting UK forestry statistics as it relates to the UK’s greenhouse gas inventory submitted under the • Minimum area of 0.1 hectares; • Tree crown cover of at least 20 per cent, or the potential to achieve it; 87 88

Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 397 • Minimum height of 2 metres, or the potential to achieve it. This definition includes felled areas awaiting restocking and integral open spaces (open areas up to 1 hectare). The annual Forestry Statistics publication uses a minimum area assumption of 0.5 ha, with the “Tree cover outside woodland” report providing the additional area of woodlands between 0.1-0.5 ha74. The definitions are consistent with information provided by the UK to the Food and Agriculture Organization of the United Nations (FAO). If an international source uses a different minimum area definition, for example 0.5 ha in the Global Forest Resource Assessment 2010, the UK areas are adjusted to this different definition (FAO, 2010). All forest areas in the UK can be regarded as managed from the point of view of regulation against deforestation and protection against fire, storms and disease. In general, forest areas are actively managed for landscape, soil protecti on, habitat conservation, amenity and recreation, which may or may not include active management for wood production. In this inventory submission the carbon uptake by UK forests is calculated using a Tier 3 carbon accounting model, C ARBINE. Overall carbon uptake is calculated as the net change in the pools of carbon in standing trees, dead organic matter , soil and products from harvested material, for conifer and broadleaf forests. The model is able to represent all of the introduced and native plantation and naturally -occurring species relevant to UK forestry, the different growth rates of forests and four broad classes of forest management (clear-fell with thinnings, clear-fell without thinnings, thinned but not clear -felled and no t imber production). The forest carbon sub -model is further compartmentalised to represent fractions associated with tree stems, branches, foliage, and roots. The CARBINE model produces separate gains and losses for carbon stock change in above- and below-ground living biomass, rather than net change. Carbon stock changes in dead wood and litter are now reported separately. Further detail on the CARBINE model is given in Annex 3.4.1 and Matthews et al.
(2014). There have been revisions to the activity data for afforestation for this these revisions and their impact are described in the recalculations (Section 6.2.7). Emissions from fluvial carbon from forest on organic soils are reported using the Tier 1 emission factors from the 2013 IPCC Wetlands Supplement for dissolved organic carbon and particulate organic carbon. Areas of forest planted on organic soils are estimated by overlaying a map of soils with the forest map from the National Forest Inventory in England, Scotland and Wales. For Northern Ireland a similar method was used to estimate areas based on the NI woodland basemap. Further details on this work are given in Annex 3.4.6. In this inventory, t here is a very small inconsistency in forest areas on organic soils in England, caused by matching the area afforested on organic soils to the area of forests estimated to exist on organic soils. This is due to slight discrepancy matching the area of defor estation on organic soils between 1990 and 2013, leading to a small over -estimate of afforestation on organic soils. Because the area involved is so small(~59ha), the difference in estimates caused by assuming these areas to be on mineral soils rather than organic soils will be close to zero. Other greenhouse gas emissions, including those arising from forest fertilisation and wildfires together with estimates of N2O emissions from forest drainage, are estimated using Tier 1 or Tier 2 approaches, and are described in Annex 3.4. Uncertainties and Time-Series Consistency The uncertainty in 1990 and 2021 respectively are estimated at 20% and 15% for CO 2, 90% and 90% for CH4, and 85% and 95% for N 2O. These uncertainties are based on an updated uncertainty analysis, broadly following the methodology of the previous uncertainty analysis,

Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 398 but using the updated activity data and methodology for this submission. Details are provided The planting statistics used as activity data mostly come from operational systems, for grants and for planting on the National Forest Estates of the four countries comprising the UK (supplemented by information from the NFI field survey). Complete geographical coverage of the UK in these statistics and accurate division of the UK into the four constituent countries is assumed and the associated statistical uncertainties are assumed to be negligible. Grants are paid once planting has occurred. The grant -aided planting is allocated by year of payment, so all the recorded planting should have taken place. There is ongoing work within the Forestry Commission to assess the level of error attached to the data, e.g. for failed planting. The area of forest in GB is based on the new NFI woodland map, together with small woods of between 0.1 and 0.5 ha . A field survey used to estimate the stocked area and composition (including age distribution) of the non -FC/NRW forest estate is based on a sub - sampling of the population and scaling to the mapped level. With regard to series • For forest carbon stock changes, N fertilization of forests and emissions from drainage, time series consistency is expected to be good as activity data are obtained consistently from the same national forestry sources; and, • For emissions from wildfires, data have been collated from several published sources. From 1990 – 2004 all data originate from the state forestry agencies so there is good time series consistency during this period. Data have been extrapolated for 2005-2009. A newer and more complete data source for England, Scotland and Wales is used from 2010 onwards, and gives wildfire burnt areas which are the same magnitude as the • Emissions from forests on organic it is assumed that all organic soils planted with forests are drained and there has been no recorded planting of new planting on organic soils since 2012. An area of 13.2 kha has been rewetted to Wetland since 2000. A significance analys is has been undertaken for key categories in the LULUCF sector. In Forest Land carbon stock changes in living biomass, dead wood and litter in the 4.A.1 Forest Land remaining Forest land and 4A2.2 Grassland converted to Forest Land are the most A1. Forest Land remaining Forest

Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 399 A2.4. Settlements converted to 4(II) Emissions and removals from drainage and rewetting and other management of organic and mineral 4(I) Direct N2O Emissions from N Inputs to Managed Soils - forest 4(II) Emissions and removals from drainage and rewetting and other management of organic and mineral 4(II) Emissions and removals from drainage and rewetting and other management of organic and mineral 4(III) N from mineralization resulting 1 Percentages may not sum to 100% due to rounding Category-Specific QA/QC and Verification This source category is covered by the general QA/QC procedures, which are discussed in Section 1.6. Information on the area affected by wildfires is consistent with that reported to the As part of a separate research project, a comparison has been made of the predictions made by the UKCEH C-Flow model and Forest Research CARBINE model. The results demonstrated that the models produce consistent predictions when given the same input data and assumptions (e.g. about woodland management practices). Further work has been undertaken comparing the inventory as predicted by CARBINE to the inventory as predicted by C-Flow and detailing the changes in assumptions that drive the changes in the inventory (Matthews et al., 2014). Verification of carbon stock changes will be under taken once the second cycle of the NFI is completed (after 2022). A review of inventory data and models has been undertaken (Levy and Rowland, 2011), during which data were collated and critically assessed on soil carbon stocks following afforestation.
Generally, soil carbon stocks are assumed to increase after afforestation in the UK, following on as a result of the increased above -ground biomass and litter inputs, based on a small number of long term studies. In fact, in the UK studies which attempt to me asure this, soil carbon stocks in forested plots were 15 to 60 % lower than in adjacent unplanted, grassland or moorland (Reay et al., 2001; Chapman et al. 2003; Zerva and Mencuccini 2005; Mitchell et al. 2007; Bellamy and Rivas -Casado 2009; Levy and Clark 2009). These results are in agreement with global meta -analyses, which have reported mean changes in soil carbon stocks of around -10 %, -7 %, +3 % and -4 % associated with conversion of pasture to forest plantation (Guo and Gifford 2002; Laganiere, Anger s et al. 2010; Poeplau, Don et al. 2011

Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 400 respectively). The treatment of the litter layer in these studies is a significant uncertainty, as it is possible that some of the reported decreases in soil carbon following afforestation were compensated by increas es in carbon stocks of the above -ground litter layer which is not The full specification and information on the validation of the soil and litter model that has been implemented in CARBINE will be published in a separate technical report. In broad terms, the comparisons done so far show that the model gives broad-scale soil carbon stock results that are consistent with collected data and reported estimates. Verification of the carbon stock changes in soils is made more difficult by the general lack of repeat measurement and we are attempting to identify potential sources of additional data. In 2018, a new automatic algorithm was introduced in CARBINE to adjust the assumptions about forest management to ensure a good match between modelled forest harvest, and thus HWP, and the wood production statistics. This has also improved the repeatability and QC of this part of the inventory. As part of this project, the timber volume production module of CARBINE was re -implemented to enabl e that automation. This semi -independent implementation of this part of the model was cross -validated against the version in the : Category-Specific Recalculations The reported overall net GHG sink in category 4A has changed between -0.2 and -0.5 Mt CO2e (-1 to -3%) across the time series compared to the previous inventory. The changes were mainly seen in the carbon stock changes in the above-ground biomass pool under Forest Remaining Forest. The main cause of this change was updates to the estimated activity data for afforestation and deforestation on organic soils. The changes and their justification • Updated activity data. Updated afforestation and deforestation statistics were included for all nations. The consistency of forest repo rting across all UK nations was improved by updating the woodland area in Northern Ireland. The assumed Felled Area on the NI Forest Service estate was adjusted to match the revised 2018 woodland area, calculated to be consistent with the 2021 NI woodland area and new planting. • Updated EF for POC emissions from organic soils. Particulate organic carbon (POC) EFs were updated for all soil categories using an IPCC Tier 1 methodology • Updated forest area on organic soils. The assumed planting on organic soils was adjusted for deforestation to achieve consistency with the revised peat soil map (for 2013 in England, 1990 in Scotland and Wales, and 2007 in NI). Forest planting in Northern Ireland in 1880 -1899 was correctly as signed to organic rather than mineral • Minor changes to average biomass densities used for wildfire emission • Updated N2O and CH4 EFs from organic soils. An updated (2022) Tier 2 analysis of organic soil emission factors (EFs) from the Defra Peatland Code Project SP0822 was implemented (Evans et al. 2022a). This update incorporates new UK datasets published since 2019, including data from the UK flux tower network, as well as international data from climatically similar regions. Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 401 value Units Comment / Justification 4A1/4(V) Biomass burning - wildfires 10.23 35.71 10.23 35.70 Gg C Minor changes to average biomass densities used for wildfire emission calculations living biomass - gains -10418.24 -16031.55 -10423.75 -16066.95 Gg C living biomass - losses 7791.00 13404.74 7814.24 13350.81 Gg C dead wood -627.54 -1012.33 -630.40 -994.28 Gg C litter -146.30 -130.52 -145.81 -132.32 Gg C soils - mineral soils -499.45 -1141.75 -498.05 -1138.12 Gg C soils - organic soils 133.72 1.59 130.88 0.20 Gg C Updated forest area on organic soils. Updated EF for POC emissions from organic soils. living biomass - gains -85.14 -35.41 -85.00 -35.40 Gg C living biomass - losses 17.69 7.03 17.66 7.02 Gg C dead wood -2.76 -0.97 -2.75 -0.97 Gg C litter -2.33 -0.87 -2.33 -0.87 Gg C soils - mineral soils 50.54 26.27 50.46 26.31 Gg C

Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 402 value Units Comment / Justification afforestation 13.71 1.28 13.78 1.29 Gg C living biomass - gains -1037.32 -248.58 -1037.03 -251.78 Gg C living biomass - losses 211.97 49.20 211.93 49.63 Gg C dead wood -34.77 -7.18 -34.76 -7.23 Gg C litter -31.04 -6.66 -31.04 -6.73 Gg C Updated forest area on organic soils. Updated EF for POC emissions from organic soils.
soils - mineral soils 428.43 186.30 427.66 187.13 Gg C afforestation 345.68 18.22 348.24 19.62 Gg C DOC 74.51 4.24 72.77 4.42 Gg C living biomass - gains -17.71 -11.26 -17.68 -11.38 Gg C living biomass - losses 3.58 2.23 3.57 2.24 Gg C dead wood -0.58 -0.33 -0.58 -0.33 Gg C

Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 403 value Units Comment / Justification litter -0.50 -0.30 -0.50 -0.31 Gg C afforestation 7.32 8.30 7.32 8.34 Gg C afforestation 6.20 0.86 6.23 0.92 Gg C Updated forest area on organic soils. Updated EF for POC emissions from organic soils. and mineral soils 3.34 3.60 3.39 3.67 Gg CH4 Updated forest area on organic soils. Updated N2O and CH4 EFs from organic soils. mineralisation 0.053 0.028 0.053 0.028 Gg N2O mineralisation 0.449 0.195 0.448 0.196 Gg N2O Updated forest area on organic soils. mineralisation 0.008 0.009 0.008 0.009 Gg N2O N Inputs to Managed Soils 0.041 0.003 0.041 0.003 Gg N2O and mineral soils 1.967 2.127 1.098 1.195 Gg N2O Updated forest area on organic soils. Updated N2O and CH4 EFs from organic soils. Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 404 Emissions sources 4B carbon stock change 4B: 4(II) Emissions and removals from drainage and rewetting and other management of organic and mineral soils 4B: 4(III) Direct N2O emissions from N mineralisation. Methods T3 for carbon stock changes, T2 for organic soils, T1 for other Emission Factors Country-specific for T3 methods, T2 for direct CO2 and CH4 emissions from organic soils, T1 for other emissions Key Categories 4B: Cropland - CO2 (L1, T1, L2, T2) Completeness No known omissions. Inclusion of a new CO2 Emission Factor for Cropland on wasted peat (peat < 40cm). Updated T2 organic soil Emission Factors and organic soils activity data. Revision of Emission Factor for Particulate Organic Carbon (POC) losses from This section describes LULUCF emissions and removals from Cropland in the UK. A description of LULUCF emissions and removals from the OTs and CDs is given in Section Net emissions from the Cropland category include carbon stock gains and losses and GHG emissions due to land-use change (LUC), cropland management , drainage and biomass burning. Overall, the Cropland category is the largest net source in the LULUCF sector. Ongoing carbon stock changes in soils arising from LUC to Cropland are reported under both 4.B.2. (for LUC in the past 20 years) and 4.B.1 (for historic LUC >20 years before the inventory reporting year). These non-organic soil net carbon stock changes are the largest component of the category total emissions and are calculated using a Tier 3 dynamic soil carbon model. Carbon emissions from drainage of cropland on organic soils are the next largest component and are calculated using Tier 2 country-specific emission factors. Other contributors to the Cropland net total emissions • CH4 emissions resulting from drainage of organic soils; • carbon stock changes in biomass and soils resulting from changes in cropland • biomass carbon stock changes due to LUC; • N2O emissions from soil disturbance associated with LUC; • biomass burning emissions of GHGs from controlled burning following forest land • biomass burning emissions of GHGs due to wildfires. All forms of land-use change, including deforestation, are considered and both mineral and organic soils are included. In some categories, e.g. Forest Land converted to Cropland, the

Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 405 area of land undergoing transition falls to zero and is subsequently reported as Not Occurring for some carbon stock changes and emissions. Ongoing N2O emissions from soil as a result of land-use change > 20 years ago and from drainage of organic soils are reported in the Agr icultural sector inventory as N 2O emissions from managed agricultural soils. UKCEH provide the appropriate areas and emission factors to Rothamsted Research. Nitrous oxide emissions from loss of soil organic matter as a result of Cropland Management are al so reported in the Agricultural sector inventory as N 2O emissions from managed agricultural soils. Emissions of CO 2, CH4 and N2O from controlled biomass burning arising from Forest Land straw or stubble) are reported under category 3F Field Burning of Agricultural Residues. Full details of the method and activity data are given in Annex 3.4. Information on approaches used for representing land areas and on land use databases used for the inventory preparation The UK uses Approach 2 (IPCC 2006) for the representation of land use areas in the inventory and compiles several different data sources into a non -spatially-explicit land use conversion matrix (see Section 6.11 and Annex 3.4.2.1 for details). Data sources that contain area information for reporting carbon stock changes and/or o The Countryside Survey (DAERA 2016, UKCEH 2020a) which gives repeated field surveys of stratified 1km sample squares. o Monitoring Landscape Change (MLC 1986) habitat survey based on aerial • Extent of cropland on organic soils and rewetting of cropland back to wetland (Evans et al. 2017 and further updates). o Areas of the main crop types are obtained from the June Agricultural Censuses o Agricultural holdings farm-level detail on agricultural land areas. o field-level register of agricultural subsidy claims under the EU Common o crop classification of satellite imagery for England, with ground-truth data from agricultural subsidy inspectors o The areas of Cropland receiving inputs of manure, fertiliser and crop residues are obtained from the British Survey of Fertiliser Practice.
• Land-cover from satellite imagery classification o Land Cover Map (UKCEH 2020b): thematic land-cover classification of satellite o Land Cover® Crops (UKCEH 2016): Based on the LCM parcel framework with additional crop information from satellite data o CORINE Land Cover (CORINE 2020): Survey of European land cover and land cover change from semi -automatic interpretation of high resolution satellite • Data on wildfires on agricultural land from Fire and Rescue service and satellite data. o Areas of wildfire on Cropland for 2010 to the present come from Fire and o Between 2001 and 2009 the area of wildfire on Cropland is calculated by using satellite data on the total area of wildfires in the UK which are apportioned to

Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 406 land use using the same ratios as found in the Fire and Rescue service data o Cropland wildfire areas prior to 2001 are extrapolated (see Annex 3.4.5 for Land-use definitions and the classification system used and their correspondence to the LULUCF categories Cropland is defined in accordance with the Agriculture, Forestry and Other Land Use Guidance (IPCC 2006). The crop types in the different data sources that contribute to the Cropland category are described in Annex 3.4.2.1. Activity data for land-use change are estimated using a land-use change (LUC) matrix approach. Detailed descriptions of the methods, emission factors and data flows used for Cropland activities are given in Annex 3.4.2. Land use change on organic soils is split out from the land-use change matrices to produce a non-organic soil set of LUC change matrices. Emissions arising from land -use and land-use change on organic soils are calculated using methodologies consistent with chapters 2 and 3 of the 2013 IPCC Wetlands supplement described in Annex 3.4.6. A dynamic model of carbon stock change is used with the non-organic LUC matrices to estimate non-organic soil carbon stock changes due to LUC. Non-organic soil carbon stock changes are modelled as changing exponentially between initial and final land uses with the most rapid change in the early years following the transition. The carbon stocks on non-organic soils for each land use category are calculated as averages for Scotland, England, Northern Ireland and Wales using a database of soil carbon density for the UK (Milne and Brown 1997; Cruickshank et al. 1998; Bradley et al. 2005) which has been constructed based on information on soil type, land cover and carbon content of soil cores to a depth of 1 m or to bedrock, whichever was the shallower, for mine ral and organo -mineral soils. The rate of loss /gain of soil carbon is dependent on the type of land use transition. A Monte Carlo approach is used to vary the rate of change, the area activity data and the values for soil carbon equilibrium, under initial and final land use. The mean soil carbon flux for each region is summed to give the UK total for the Inventory. Biomass carbon stock change is calculated using the LUC matrix and literature-derived Tier 2 stock change factors, with all stock gains or losses assumed to occur in a single year. N2O emissions associated with non-organic soil disturbance from LUC are reported using the areas of Forest land and Grassland converted to Cropland from the LUC matrices and the Carbon stock change (CSC) in mineral soils as a result of cropland management is estimated using agricultural survey activity data , country-specific soil carbon densities and Tier 1 CSC factors for most activities except for tillage reduction (Tier 2). Carbon stock changes in biomass due to cropland management activities are estimated using literature-derived Tier 2 stock change factors and activity data from agricultural surveys. Carbon stock changes in biomass can arise from changes in annual crops, orchards, bioenergy crops and shrubby perennial crops (see Annex 3.4 for details). Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 407 Emissions of carbon and CH4 from Cropland on drained organic soils are reported using Tier 2 emission factors (Annex 3.4.6 ). Emissions of N 2O fro m cropland on organic soils are calculated using the same activity data and are reported in category 3.D in the Agriculture 6.3.4.4 Biomass burning emissions Emissions from controlled burning on cropland are only reported for Forest Land conversion to Cropland and are estimated using Tier 1 emission factors and country-specific fuel densities. Emissions from wildfires on Cropland are reporting using Tier 1 emission factors and activity from a range of sources (see Section 6.3.2). Uncertainties and Time-Series Consistency The uncertainty in 1990 and 20 21 respectively are estimated at 15% and 20% for CO2, 65% and 70% for CH4, and 35% for N2O. These uncertainties are based on an updated uncertainty analysis, broadly following the methodology of the previous uncertainty analysis, but using the updated activity data and methodology for this submission . Details are provided in Annex 3.4.12. The areas undergoing land -use change are the biggest source of uncertainty in the LULUCF inventory (see Annex 3.4.12). With regard to time series • Drainage of organic it is assumed that all drainage of organic soils on Cropland occurred before 1971 as recent policy has favoured protection of organic soils. There have been no policy incentives to encourag e new land drainage for agricultural use since 1990, and major drainage of large areas of Cropland on organic soils in areas such as the East Anglian fens is known to have occurred well before this. A small area has been rewetted to Wetland since 2000 (5.5 kha), all of which is in England. • Changes in biomass and soil carbon due to the land-use change data assimilation methodology draws on multiple data-sources and takes account of random uncertainty and false positive rates.
The time series now show more inter-annual variation but more • Controlled biomass burning after conversion of Forest Land to there is good time series consistency as there has been continuity in the activity data source. • a consistent dataset is used from 2010 onwards. Burnt areas are extrapolated back to 2001 based on remote sensing data, but between 1990 and 2001 there are no observed data on the extent of wildfires on Cropland, and the time series is filled by extrapolating the 2001 – 2011 average wildfire area. • Cropland The June Agricultural censuses are very long -standing datasets with good time series consistency. The British Survey of Fertiliser Practice has contained information on the proportion of Cropland receiving manure since 2008. For years prior to 2008, the 2008 – 2015 average value has been used. The British Survey of Fertiliser Practice has contained information on the proportion of Cropland receiving fertiliser since 1992. For years prior to 1992, the 1992 - 2001 average value A significance analysis has been undertaken for key categories in the LULUCF sector. In Cropland the 4.B2.2 Grassland converted to Cropland and the 4.B1 Cropland remaining in mineral and organic soils the biggest pool contributions. Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 408 B1. Cropland remaining Cropland 40% 63% cropland management (soils and Mineral Soils (due to land use B2.1. Forest Land converted to B2.4. Settlements converted to • 1 Percentages may not sum to 100% due to rounding Category-Specific QA/QC and Verification This source category is covered by the general QA/QC procedures, which are discussed in A resampling of the 1980-based National Soil Inventory (NSI) in England and Wales in 1995- 2003 found large losses of soil carbon across all land use types (Bellamy et al. 2005). It was hypothesized that this loss was due to climate change because all land uses showed losses and the size of the loss was related to initial carbon concentration, suggesting that the UK’s LUC modelling approach was incorrect. In contrast, a more recent study using Countryside Survey (CS) data (Reynolds et al. 2013) found no significant change in soil carbon stocks under most Grassland habitat types between 1978 and 2007. The reason for the different results obtained by NSI and CS is not clear (Kirk et al . 2011), alt hough there are methodological differences between the two surveys. Subsequent modelling studies (e.g. Smith et al . 2007, Barraclough et al . 2015) have shown that climate changes could only account for a small part of the decrease in soil carbon reported i n Bellamy et al. (2005). The importance of prior land use history in priming soil carbon dynamic models has also been Category-Specific Recalculations The reported overall net GHG source in category 4B has decreased by -1.7 Mt CO2e (-10 to - 11%) across the time series compared to the previous inventory. The changes were mainly in organic soil carbon emissions in Cropland remaining Cropland. The changes and their justification • Updated EFs from organic soils. An updated (2022) Tier 2 analys is of organic soil emission factors (EFs) from the Defra Peatland Code Project SP0822 was

Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 409 implemented (Evans et al. 2022a). This update incorporates new UK datasets published since 2019, including data from the UK flux tower network, as well as international data from climatically similar regions. This included the introduction of a new emission factor for direct CO2 from Cropland on wasted peat (peat < 40cm) from the BEIS Wasted Peat Project (Evans et al. 2022b). Particulate organic carbon (POC) EFs were updated for all soil categories using an IPCC Tier 1 methodology (IPCC 2014 • Revisions to organic soil areas. Revisions to the organic soils maps were included from a BEIS Ad -hoc project to edit and check the geometry of the maps and clarify activity data and the assumptions used to create the maps in Evans et al. 2017. • Updated deforestation activity data. Updated deforestation statistics were included

Land-Use, Land-Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 410 value Units Comment / Justification biomass 6.16 -1.18 6.16 -0.74 Gg C Revisions to organic soil areas. Net carbon stock change in soils - mineral soils 496.19 1200.87 496.86 1201.51 Gg C Net carbon stock change in soils - organic soils 1614.77 1545.36 1145.96 1081.46 Gg C Updated EFs from organic soils. 4B2.1/4(V) Biomass Burning 0.24 0.00 0.24 0.00 Gg C Updated deforestation activity data Net carbon stock change in dead organic matter 0.08 0.00 0.08 0.00 Gg C Net carbon stock change in soils - organic soils 0.00 0.08 0.00 0.07 Gg C Updated deforestation activity data Revisions to organic soil areas. Net carbon stock change in living biomass 0.34 0.00 0.34 0.00 Gg C Updated deforestation activity data 4B2/4(II) Emissions and removals from drainage and rewetting 11.671 11.169 11.863 11.368 Gg CH4 Updated EFs from organic soils. Revisions to organic soil areas. Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 411 Category-Specific Planned Improvements The second step in implementing the BEIS-funded Land-Use Tracking project is in progress in 2022-23 (see Annex 3.4.1.2). This will revise the soil carbon dynamics model and LULUCF inventory reporting methods to use vectors of land-use change rather than independent annual land-use change matrices, which will improve the representation of rotational management of cropland and improved grassland. We also plan to undertake further analysis of the relationship between soil type and land -use vectors, and the potential for priming the soil carbon dynamic model with pre-1950 land-use change history. A BEIS-funded research project on GHG emissions from lowland wasted peat soils under intensive agriculture was delayed by the COVID-19 pandemic.
Flux tower measurements from this study have been used to develop a specific Tier 2 CO2 EF for Cropland on Wasted Peats, present, separate EFs for grassland on wasted peat cannot be derived due to lack of data, and measurements are ongoing for N2O, with further results expected in 2023. The 2019 UNFCCC review team i nquired about the estimation, and reporting of, inorganic carbon stock change in soil . A subsequent review team stated that this only needs to be considered when the necessary data, a monitoring system for routinely collecting such data, and appropriate (Tier 3) soil process -modelling capacity becomes available. Therefore, no further work on inorganic soil carbon stocks is currently planned. Emissions sources 4C carbon stock change 4C: 4(II) Emissions and removals from drainage and rewetting and other management of organic and mineral soils 4C: 4(III) Direct N2O emissions from N mineralisation. Methods T3 for carbon stock changes, T2 for organic soils, T1 for other Emission Factors Country-specific for T3 methods, T2 for direct CO2 and CH4 emissions from organic soils, T1 for other emissions Key Categories 4C: Grassland - CO2 (L1, T1, T2), CH4 (L1, T1, L2, T2) Completeness No known omissions- areas are reported for land uses with no Updated T2 organic soil Emission Factors and organic soils activity data. Revision of Emission Factor for Particulate Organic Carbon (POC) losses from organic soils. This section describes LULUCF emissions and removals from Grassland in the UK. A description of LULUCF emissions and removals from the OTs and CDs is given in Section Net emissions from the Grassland category include carbon stock gains and losses and GHG emissions due to land-use change (LUC) and GHG emissions from grassland management ,

Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 412 drainage and rewetting and biomass burning . Grassland is a small net source that reduces Ongoing carbon stock changes in soils arising from LUC to Grassland are reported under both 4.C.2 Land Converted to Grassland (for LUC in the past 20 years) and 4.C.1 Grassland Remaining Grassland (for historic LUC >20 years before the inventory reporting year). These soil carbon stock changes and CO2 emissions from mineral and organic soils are the largest components of the category total emissions and removals. Carbon stock changes on mineral soils are calculated using a Tier 3 dynamic soil carbon model and CO2 emissions from organic soils are calculated using Tier 2 country-specific emission factors. The area of undisturbed grassland on mineral soils which has not been converted from other land uses in the past is reported in 4.C.1. “Undisturbed” grassland. This sub-category is used as a buffer category on the recommendation of UNFCCC reviewers, as Grassland is the most extensive land type in the UK. The undisturbed grassland area is calculated as the difference between the total land area (from the official national statistic of UK land area, Office for National Statistics) and the sum of all other land use areas (calculated from land use matrices, afforestation areas, organic soil areas etc.) for each year. No anthropogenic emissions or removals are associated with this undisturbed area. The Evans et al. (2017) report identified large areas of grassland on organic soils in the UK that are not intensively cultivated but nevertheless have been degraded by anthropogenic activities, for example by over -grazing or management for game species. Emissions of N 2O from these unintensive grassland areas are reported under 4C Grassland, while N 2O emissions from intensive cultivated grassland on organic soils are reported under 3D in the Other contributors to the Grassland net total emissions • CH4 emissions resulting from drainage and rewetting of organic soils; • N2O emissions from drainage and rewetting of unintensive grassland on organic soils; • carbon stock changes in biomass resulting from changes in grassland management; • biomass carbon stock changes due to LUC; • N2O emissions from mineral soil disturbance associated with LUC; • biomass burning emissions of GHGs from controlled burning following forest land • biomass burning emissions of GHGs due to wildfires. Full details of the methods and activity data are given in Annex 3.4 Information on approaches used for representing land areas and on land use databases used for the inventory preparation The UK uses Approach 2 (IPCC 2006) for the representation of land use areas in the inventory and compiles several different data sources into a non -spatially explicit land use conversion matrix (see Section 6.1.1 and Annex 3.4.2.1 for details). Data sources that contain area information for reporting carbon stock changes and/or • Habitat/landscape surveys (see Section 6.3.2). • Extent of grassland on organic soils and rewetting of grassland that stays within the grassland category (Evans et al. 2017 and further updates). • Agricultural survey data (see Section 6.3.2). • Land-cover from satellite imagery classification (see Section 6.3.2). • Data on deforestation areas from various

Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 413 o Post-2000 deforestation areas are assessed from the NFI and administrative records of the conversion of areas in the public forest estate as part of habitat restoration and windfarm development. o 1990-1999 deforestation areas are estimated from unconditional felling licence data (felling licences granted without a requirement to restock), national forest estate administrative information and land conversion ratios from Countryside Survey. Details are given in Annex 3.4.4. • Data on wildfires on agricultural land and moorland from Fire and Rescue service and satellite data (see Section 6.3.2 for further details). Land-use definitions and the classification system used and their correspondence to the LULUCF categories Grassland that has undergone land-use change and direct management is defined in accordance with the Agriculture, Forestry and Other Land Uses guidance (IPCC 2006).
There are also large areas of extensively grazed semi-natural grassland on mineral soils, which are assigned to the 4.C.1 “ Undisturbed grassland” sub -category and calculated as the area remaining after all other land use areas are subtracted from the total UK land area. This is the buffer land use category for the UK, so may contain small areas of other land uses that are not Grazing is the main land use on semi-natural peatland habitats that would otherwise fall within in the Wetland category , so areas of peatland habitat not used for p eat extraction or not explicitly identified as near-natural bog or fen, are included in the Grassland category. Areas of grassland that have undergone rewetting (or other activities that restore peatland habitats and reduce emissions) remain within the Grassland category. The grassland and semi -natural habitat types in the different data sources that contribute to the Grassland category are described in Annex 3.4.2.1. Activity data for land-use change are estimated using a land-use change (LUC) matrix approach. Detailed descriptions of the methods, emission factors and data flows used for the Grassland activities are given in Annex 3.4.2. Land use change on organic soils is split out from the land-use change matrices to produce a non-organic soil set of LUC change matrices. Emissions arising from land use and land -use change on organic soils are calculated using methodologies consistent with chapters 2 and 3 of the 2013 IPCC Wetlands Supplement described in Annex 3.4.6. The dynamic model of soil carbon stock change is described in Section 6.3.4. Biomass carbon stock change is calculated using the LUC matrix and literature-derived Tier 2 stock change factors with all stock gains or losses assumed to occur in a single year. N2O emissions associated with the non-organic soil disturbance from LUC are reported using the appropriate areas of Grassland remaining Grasslan d and Forest land converted to Grassland from the LUC matrices and the IPCC Tier 1 emission factors. Carbon stock changes in biomass due to grassland management activities are estimated using literature-derived Tier 2 stock change fact ors and activity data from agricultural surveys. All carbon stock changes associated with changes in the length and condition of hedgerows are

Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 414 Emissions of carbon and CH 4 from Grassland on drained and undrained organic soils, and N2O emissions from unintensive grassland, are reported using Tier 2 emission factors (Annex 3.4.6). Emissions of N 2O from intensive grassland on organic soils are calculated using the same activity data and are reported in category 3.D in the Agriculture sector. 6.4.4.4 Biomass burning emissions Emissions from controlled burning on grassland are only reported for Forest Land conversion to Grassland and are estimated using Tier 1 emission factors and country -specific fuel densities. See Annex 3.4.5 for further discussion of controlled burning for game management Emissions from wildfires on Grassland (agricultural grassland and semi-natural grassland) are reporting using Tier 1 emission factors and activity from a range of sources (see Section 6.3.2) Uncertainties and Time-Series Consistency The uncertainty in 1990 and 2021 respectively are estimated at 15% for C O2, 35% for CH 4, and 45% for N2O. These uncertainties are based on an updated uncertainty analysis, broadly following the methodology of the previous uncertainty analysis, but using the updated activity data and methodology for this submission . Details are provided in Annex 3.4.12. The areas undergoing land-use change are the biggest source of uncertainty in the LULUCF inventory With regard to time series • Drainage of organic it is assumed that all drainage of organic soils under Grassland occurred before 1990, as policy has favoured protection of organic soils. There have been no policy incentives to encourage new lan d drainage for agricultural use since before 1990, and major drainage of large areas of improved Grass land on organic soils in areas such as the Somerset Levels fens is known to have occurred well before this. An area of 90.92 kha of grassland has been rewetted since 1990, and an area of 1.52 kha has been converted to peat extraction since 1990. • Changes in biomass and soil carbon due to the land-use change data assimilation methodology draws on multiple data-sources and takes account of random uncertainty and false positive rates. The time series now show more inter-annual variation but more • Controlled biomass burning after conversion of Forest Land to there is good time series consistency as there has been continuity in the activity data source. • Grassland act ivity data come from Countryside Survey, which is also used to estimate change in carbon stocks due to land-use change and has good • a consistent dataset is used for 2010 onwards. Burnt areas are extrapolated back to 2001 based on remote sensing data, but between 1990 and 2001 there are no observed data on the extent of wildfires on Grassland, and the time series is filled by extrapolating the 2001 - 2011 average wildfire area. 6.8). The largest contributing sub-categories/pools for carbon dioxide are from Grassland remaining Grassland organic and mineral soils and Cropland converted to Grassland mineral soils. The largest contri butory sub -category for methane is almost entirely emissions from drainage and rewetting of organic soils. Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 415 C1. Grassland remaining Grassland 61% 66% biomass due to land use change 0% 0% C2.1. Forest Land converted to C2.2. Cropland converted to Grassland 35% C2.4.
Settlements converted to 4(II) Emissions and removals from drainage and rewetting and other management of organic and mineral 1 Percentages may not sum to 100% due to rounding Category-Specific QA/QC and Verification This source category is covered by the general QA/QC procedures, which are discussed in As discussed in Section 6.3.6 resampling of the 1980-based National Soil Inventory (NSI) in England and Wales in 1995-2003 found large losses of soil carbon across all land use types (Bellamy et al. 2005) but, a more recent study using Countryside Survey (CS) data (Reynolds et al. 2013) found no significant change in soil carbon stocks under most Grassland habitat types between 1978 and 2007. The possible reasons for these differences are unclear, as Category-Specific Recalculations The Category 4C net source has decreased by between -0.6 to -0.7 Mt CO2e (-22 to -67%) across the time series compared to the previous inventory. The changes were mainly in organic soil carbon stock change in Grassland remaining Grassland. The changes and their justification • Updated EFs from organic soils. An updated (2022) Tier 2 analysis of organic soil emission factors (EFs) from the Defra Peatland Code Project SP0822 was implemented. This update incorporates new UK datasets published since 2019, including data from the UK flux tower network, as well as international data from

Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 416 climatically similar regions. Particulate organic carbon (POC) EFs were updated for all soil categories using an IPCC Tier 1 methodology (IPCC 2014 Appendix Eq.2A.1). • Revisions to organic soil areas. Revisions to the organic soils maps were included from a BEIS Ad -hoc project to edit and check the geometry of the maps and clarify activity data and the assumptions used to create the maps in Evans et al. 2017. This resulted in a revision of the restoration data for intensive grassland, where an error was identified in t he Peatland Compendium dataset, which overestimated intensive grassland to rewetted fen restoration in south-west England. Updated restoration data were supplied by Natural England and the RSPB. • Updated deforestation activity data. Updated deforestation statistics were included • Minor changes to average biomass densities used for wildfire emission

Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 417 IPCC Category Source Name Old 1990 value Old 2020 value Units Comment / Justification organic soils 1792.18 1574.30 1592.34 1363.84 Gg C Revisions to organic soil areas. Updated EFs from organic soils. controlled burning 5.67 50.35 5.67 46.13 Gg C living biomass - Losses 8.03 66.14 8.03 60.20 Gg C Updated deforestation activity data matter 1.91 22.11 1.91 20.66 Gg C organic soils 0.08 16.13 0.10 24.11 Gg C Revisions to organic soil areas Updated deforestation activity data and mineral soils 94.98 95.99 99.80 100.96 Gg CH4 Updated EFs from organic soils. Revisions to organic soil areas. wildfires 0.34 0.23 0.34 0.24 Gg CH4 Minor changes to average biomass densities used for wildfire emission controlled burning 0.06 0.55 0.06 0.51 Gg CH4 Revisions to organic soil areas Updated deforestation activity data and mineral soils 0.59 0.50 0.42 0.37 Gg N2O Revisions to organic soil areas. Updated EFs from organic soils. Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 418 IPCC Category Source Name Old 1990 value Old 2020 value Units Comment / Justification wildfires 0.031 0.021 0.031 0.022 Gg N2O Minor changes to average biomass densities used for wildfire emission Controlled Burning 0.003 0.031 0.003 0.028 Gg N2O Revisions to organic soil areas Updated deforestation activity data

Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 419 Category-Specific Planned Improvements The second step in implementing the BEIS-funded Land-Use Tracking project is in progress in A BEIS-funded research project on GHG emissi ons from lowland wasted peat soils under intensive agriculture was delayed by the COVID-19 pandemic. Flux tower measurements from this study have been used to develop a specific Tier 2 CO2 EF for Cropland on Wasted Peats, present, separate EFs for grassland on wasted peat cannot be derived due to lack of data, and measurements are ongoing for N2O, with further results expected in 2023. Emissions sources 4D Carbon stock change 4D: 4(II) Emissions and removals from drainage and rewetting and other management of organic and mineral soils Methods T2 for organic soils, T1 for water bodies Emission Factors T2 for direct CO2 and CH4 emissions from organic soils, T1 for Key Categories 4D Wetlands- CH4 (L1, T1, L2, T2) Completeness No known omissions- areas are reported for land uses with no since last submission Updated T2 organic soil Emission Factors and organic soils activity data. Revision of Emission Factor for Particulate Organic Carbon (POC) losses from organic soils. This section describes LULUCF emissions and removals from Wetland in the UK. A description of LULUCF emissions and removals from the OTs and CDs is given in Section 6.8. Net emissions from the Wetlands category includes emissions peatlands that are cleared and drained for peat production (for energy or horticultural purposes) ; areas of near -natural peatland; areas of former peat extraction, forest and cropland that are now rewetted; and areas converted to permanently flooded land (reservoirs). Emissions from on -site peat production and off -site emissions from horticultural peat are reported under 4.D.1 Wetlands remaining Wetlands. Areas of former peat extraction that are now rewetted are reported under 4D 1.3. There are areas of conversion to Wetlan d of grassland converted to Wetland for peat extraction (4.D.2.1) , grassland converted to flooded land (4.D.2.2) and rewetted former forest and cropland (4 D.2.3) .
The associated emissions and living biomass carbon stock changes estimated using the appropr iate Tier 1 or 2 The area of UK natural inland water is reported in the category Other Wetlands remaining Other Wetlands and the area of reservoirs created before 1990 is reported in Flooded Land

Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 420 Information on appr oaches used for representing land areas and on land use databases used for the inventory preparation The approach used for representing Wetlands differs from that used for other land use categories because peat extraction sites and reservoirs are not expli citly identified in the habitat and landscape surveys used for the land use matrix. The area of wetlands on organic soils in the UK was revised based on peatland extent and condition mapping outputs from the BEIS-funded project to implement the IPCC Wetlan d Supplement (Evans et al. 2017). This included areas of near-natural wetlands and rewetted organic soils as well as areas of inactive peat extraction. These peatlands maps were updated for use in this submission (see Annex This information is supplemented by the areas of a ctive peat extraction obtained from the Directory of Mines and Quarries, Google Earth, the Minerals Extraction in Great Britain report (and its predecessor the Minerals Raised Inquiry, Office for National Statistics) , and site operations data provided by Growing Media Association. These sources and papers on peat extraction in Northern Ireland were used in combination to produce an activity dataset for active peat extraction areas in the UK (see Annex 3.4.8 for further details). Activity data for post -1990 constructed reservoirs were compiled from the Public Register of Large Raised Reservoirs (supplied by the Environment Agency for England and Wales) and the SEPA Water Body Classification database (see Annex 3.4.9 for further details). The remaining area of inland water (natural water bodies and reservoirs established before 1990) is known from the area of inland water reported as part of the Standard Area Measurement. There are no emissions or removals associated with this area. Land-use definitions and the classification system used and their correspondence to the LULUCF categories Areas of active peat extraction are defined as areas that are currently undergoing, or have recently undergone, peat extraction activities (locations are known from administrative see Section 6.5.2). It is assumed that extraction areas continue to produce emissions whi le there is visible evidence of exposed peat soil from Google Earth satellite imagery, and do not convert back to functioning peatlands without restoration intervention . An extraction site is considered to have ceased emissions when there is visible eviden ce of the re-establishment of vegetation cover on the satellite imagery and evidence of rewetting (ditch blocking) from online documentation of the restoration works and communication with site managers. “Near-natural” peatlands are areas that were identi fied in Evans et al (2017) as having no anthropogenic degradation, but can still be considered as managed e.g. for biodiversity purposes. They are a carbon sink but also a source of CH4 emissions. Rewetted peatlands are those that have undergone restoratio n activities to restore normal peatland biogeochemical functioning. These have been identified from a database of peatland restoration projects (see Annex 3.4.6) and more recent government-funded restoration. The area of inland water is taken from the “UK Standard Area Measurements” (Office for National Statistics). It defines inland water as ‘bounded’ permanent water bodies, e.g. lakes, lochs and reservoirs, exceeding 1 km2 (100 hectares) in area. ‘Open’ tracts of water, e.g. rivers, canals and streams are excluded from this definition. Reservoirs (flooded land) were identified either by their inclusion in the Public Register of Large Raised Reservoirs or by their classification as “Heavily modified” in the SEPA Water Body Classification database. Areas of water below the size threshold are included in the 4F Other Land category. Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 421 Emissions from peat extraction are estimated using Tier 1 and Tier 2 methodology, which does not distinguish between peat extraction productio n phases, i.e. it includes conversion and vegetation clearing. On -site emissions associated with peat extraction are reported under 4.D.1.1. . For on-site emissions due to extraction activities and drainage, a Tier 2 CO2 emission factor is employed for Ind ustrial (horticulture) Extraction, and a Tier 1 CO 2 emission factor (IPCC, 2014) is used for Domestic (fuel) Extraction. A Tier 2 CH4 emission factor and Tier 1 N2O emission factor is applied to emission estimates for both Industrial and Domestic Peat has been extracted is assumed to be emitted during the extraction year. Mapping outputs from Evans et al. (2017) and administrative records categorise sites as producing horticultural or energy source (fuel) peat. Further information is given in Annex 3.4.8. Google Earth imagery is used to track the change in the area of individual extraction sites over time. Google Earth is imagery is checked annually and extraction site areas are updated as new imagery becomes available. The site records show that the area under active horticultural peat extraction between 1990 and 2021 diminished for England, and decreased slightly overall for Scotland, and decreased slightly then increased recently for Northern Ireland. No peat extraction is reported in Wales. The time series of active fuel peat extraction has decreased across the UK. Sites that have no active record of extraction and show no change in area on the Google Earth imagery, are assumed to be abandoned extraction sites that are still producing emissions (reported under 4D1). Sites where extraction is no longer visible on the Google Earth imagery are identified as potentially being restored to rewetted Wetland and investigated further. As these sites are often part of peatland restoration schemes managed by UK nature reserves, information on site history and success of the restoration (rewetting) works are gathered online and from reserve managers to support a condition change.
Changes in organic soil carbon from this condition change are reported using a Tier 2 approach based on the IPCC 2014 Guidelines. A small area of land conversion to Wetlands (all from Grassland) occurs across the time series. This area and the associated on -site emissions are reported under 4D.2.1.2 Land converted to Wetlands. Rewetted former peat extraction sites remain as Wetland and are reported under 6.5.4.2 Land converted to Flooded Land A Tier 1 methodology was applied for emissions from Flooded Lands (4D.2.2.3). This estimated carbon stock changes in living biomass stock in the year of flooding (for reservoirs established since 1990) but not carbon stock changes in soils. The locations of the reservoirs were established on maps, and due to their location in upland areas, all were assumed to be Grassland prior to flooding. A living biomass density of 2 t dry matter/ha was used to estimate 6.5.4.3 Land converted to other wetlands Forest and cropland on organic soils that undergo rewetting are converted to Wetlands, as they do not retain their original land use. A Tier 2 methodology using areas and EFs from Evans et al (2017) is applied. Emissions from controlled burning following deforestation and carbon stock changes in biomass and dead organic matter are also calculated for conversion

Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 422 Uncertainties and Time-Series Consistency The uncertainty in 1990 and 20 21 respectively are estimated at 40% for CO2, 50% and 45% for CH 4, and 120% and 100% for N 2O. These uncertainties are based on an updated uncertainty analysis, broadly following the methodology of the previous uncertainty analysis, but using the updated activity data and methodology for this submission. Details are provided Time-series consistency for activity data for peat extraction sites is affected by uncertainty in survey dates but has been improved by the incorporation of additional site data fro m the Growing Media Association. Time-series consistency for flooded lands was good due to the complete nature of the data set. Methane emissions from category 4D are a key category and are entirely due to emissions Category-Specific QA/QC and Verification Operational site areas are provided by the Growing Media Association. The UKCEH peat extraction database matched the GMA data closely for Scotland, Wales, and Northern Ireland, but were adjusted accordingly where more robust data were available. For England, the inventory areas were revised downwards based on improved on -site information primarily for The peat extraction site activity dataset has also been partially ver ified by comparing the measured areas with reported areas of planning permission, which were available for some extraction sites in England and Scotland. The measured areas either matched or were smaller than the planning permission areas, which is to be e xpected as it is known that not all areas with planning permission are undergoing active extraction. The locations and previous land -use of new reservoirs were verified using the geographic information portal. Category-Specific Recalculations The Category 4D net source has increased by between 0.1 and 0.2 Mt CO2e (4-5%) across the time series compared to the previous inventory. The changes and their justification • Updated EFs from organic soils. An updated (2022) Tier 2 analysis of organic soil emission factors (EFs) from the Defra Peatland Code Project SP0822 (Evans et al. 2022a) was implemented. This update incorporates new UK datasets published since 2019, including data from the UK flux tower network, as well as international data from climatically similar regions. Particulate organic carbon (POC) EFs were updated for all soil categories using an IPCC Tier 1 methodology (IPCC 2014 Appendix Eq.2A.1). • Revisions to organic soil areas. Revisions to the organic soils maps were included from a BEIS Ad-hoc project to edit and check the geometry of the maps and clarify activity data and the assumptions used to create the maps in Evans et al. 2017. This resulted in a revision of the restoration data for intensive grassland, where an error was identified in the Peatland Compendium dataset, which overestimated intensive grassland to rewetted fen restoration in south-west England. Updated restoration data were supplied by Natural England and the RSPB. • Minor adjustments to peat extraction areas. Minor adjustments were made to the Google Earth derived areas of active peat extraction for Scotland and Northern

Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 423 value Units Comment / Justification D1.1 Net carbon stock change in soils 637.65 553.24 678.32 586.12 Gg C Minor adjustments to peat extraction areas. Updated EFs from organic soils. Revisions to organic soil areas. D1.3 Net carbon stock change in soils -482.12 -470.40 -496.27 -495.84 Gg C Updated EFs from organic soils. Revisions to organic soil areas. D2.1 Net carbon stock change in soils 0.23 4.91 0.31 6.23 Gg C Minor adjustments to peat extraction areas. Updated EFs from organic soils. D2.3.1/4(V) Biomass Burning 0.00 25.11 0.00 25.20 Gg C biomass - losses 0.00 32.85 0.00 33.02 Gg C Revisions to organic soil areas. Updated deforestation activity data Net carbon stock change in dead organic matter 0.00 11.16 0.00 11.14 Gg C D2.3.1 Net carbon stock change in soils 0.00 0.95 0.00 0.99 Gg C Revisions to organic soil areas. Updated EFs from organic soils. Updated deforestation activity data D2.3.2 Net carbon stock change in soils 0.00 7.44 0.00 0.27 Gg C Revisions to organic soil areas. Updated EFs from organic soils. drainage and rewetting and other mineral soils 78.47 81.47 82.62 84.73 Gg CH4 Updated EFs from organic soils. Revisions to organic soil areas. drainage and rewetting and other mineral soils 0.071 0.068 0.071 0.067 Gg N2O Updated EFs from organic soils. Revisions to organic soil areas.
Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 424 Category-specific planned improvements There are ongoing discussions with policy experts and peatland managers to improve the register of peat restoration activities across all nations of the UK, and update the rewetting activity data as appropriate. BEIS commissioned a review of current knowledge and gaps of GHG emissions and removals from UK coastal wetlands , which provided recommendations for moving towards inclusion of saltmarshes in the UK GHGI (Burden and Clilverd, 2022). Evidence gaps identified in this report are being addressed in a Defra-funded project (30120) to provide a road-map for inclusion of saltmarsh in the UK GHGI by defining terminology, and mapping implications of different terminologies on saltmarsh areal extent. Emissions sources 4E Carbon stock change 4C: 4(II) Emissions and removals from drainage and rewetting and other management of organic and mineral soils 4E: 4(III) Direct N2O emissions from N mineralization Methods T3 for carbon stock changes, T2 for organic soils, T1 for other Emission Factors Country-specific for T3 methods, T2 for direct CO2 and CH4 emissions from organic soils, T1 for other emissions Key Categories 4E: Settlements – CO2 (L1, T1, L2, T2) Completeness No known omissions- areas are reported for land uses with no This section describes LULUCF emissions and removals from Settlement in the UK. A description of LULUCF emissions and removals from the OTs and CDs is given in Section Net emissions from the Settlements category include carbon stock gains and losses due to land-use change (LUC) and associated GHG emissions. It is the second largest net source in Ongoing carbon stock changes in soils and direct N2O emissions from N mineralization arising from LUC to Settlements are reported under both 4.E.1 Settlements remaining Settlements (for historic LUC >20 years before the inventory reporting year) and 4.E.2 Land converted to Settlements (for LUC in the past 20 years). These non-organic soil net carbon stock changes are the largest component of the category total emissions and are calculated using a Tier 3 Other contributors to the Settlements net total emissions • Carbon, CH4 and N2O emissions resulting from drainage of organic soils; • biomass carbon stock changes due to LUC; • N2O emissions from soil disturbance associated with LUC; and

Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 425 • biomass burning emissions of GHGs from controlled burning following forest land Full details of the methods and activity data are given in Annex 3.4. Information on approaches used for representing land areas and on land use databases used for the inventory preparation The UK uses Approach 2 (IPCC 2006) for the representation of land use areas in the inventory, and compiles several different data sources into a non -spatially-explicit land use conversion matrix (see Section 6.1.1 and Annex 3.4.2.1 for details). Data sources that contain area information for reporting carbon stock changes and/or emissions from Settlements • Habitat/landscape surveys (see Section 6.3.2). • Extent of settlement on organic soils (Evans et al. 2017 and further updates). • Land-cover from satellite imagery classification (see Section 6.3.2). • Data on deforestation areas from various sources; o Post-2000 deforestation areas are assessed from t he NFI and administrative records of the conversion of areas in the public forest estate as part of habitat restoration and windfarm development. o Pre-2000 deforestation areas are estimated from unconditional felling licence data (felling licences granted without a requirement to restock), national forest estate administrative information and land conversion ratios from Countryside Survey. Details are given in Annex 3.4.4. Land-use definitions and the classification system used and their correspondence to the LULUCF categories Settlement is defined in accordance with the Agriculture, Forestry and Other Land Use The settlement land-cover types in the different data sources that contribute to the Settlement category are described in Annex 3.4.2.1. Activity data for land-use change are estimated using a land-use change (LUC) matrix approach. Detailed descriptions of the methods, emission factors and data flows used for the Settlement activities are given in Annex 3.4.2. Land use change on organic soils is split out from the land-use change matrices to produce a non-organic soil set of LUC change matrices. Emissions arising from land use and land -use change on organic soils are calculated using methodologies consistent with chapters 2 and 3 of the 2013 IPCC Wetlands Supplement described in Annex 3.4.6. The dynamic model of soil carbon stock change is described in Section 6.3.4. Biomass carbon stock change is calculated using the LUC matrix and literature-derived Tier 2 stock change factors with all stock gains or losses ass umed to occur in a single year. Detailed descriptions of the methods, emission factors and data flows used for the Settlement category are given in Annex 3.4.7. N2O emissions associated with the non-organic soil disturbance from LUC are reported using the areas from the LUC matrices and the IPCC Tier 1 emission factors. Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 426 Emissions of carbon, CH 4 and N2O from Settlements on drained organic soils are reported using Tier 2 and Tier 1 emission factors (Annex 3.4.6). 6.6.4.3 Biomass burning emissions Emissions from controlled burning on settlement land are only reported for Forest Land conversion to Settlements and are estimated using Tier 1 emission factors and country-specific Uncertainties and Time-Series Consistency The uncertainty in 1990 and 2021 respectively are estimated at 45% and 50% for CO2, 60% and 50% for CH 4, and 130-135% for N 2O. These uncertainties are based on an updated uncertainty analysis, broadly following the methodology of the previous uncertainty analysis, but using the updated activity data and methodology for this submission. Details are provided in Annex 3.4.12. The areas undergoing land-use change are the biggest source of uncertainty in the LULUCF inventory (see Annex 3.4.12).
With regard to time series • Drainage of organic It is assumed that all existing Settlement areas on organic soils are drained. The only land use change from Settlement on organic soils is to and from Forest land and the areas involved are small ( 1.66 kha to Forest Land since 1990, and 3.70 kha from Forest Land since 1990) and all assumed to be drained. • Changes in biomass an d soil carbon du e to the land -use change data assimilation methodology draws on multiple data -sources and takes account of random uncertainty and false positive rates. Estimated rates of change are lower and more gradual than in previous submissions, although the uncertainty bounds are • Controlled biomass burning after conversion of Forest Land to there is good time series consistency as there has been continuity in the activity data source. A significance analysis has been undertaken for key categories in the LULUCF sector. Carbon stock changes in mineral soils in 4E1 Settlements remaining Settlements and 4.E2.3 E1. Settlements remaining Settlements 27% 42% Carbon stock change in biomass E2.1. Forest Land converted to E2.2. Cropland converted to Settlements 9% 7% 1 Percentages may not sum to 100% due to rounding

Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 427 Category-Specific QA/QC and Verification This source category is covered by the general QA/QC procedures, which are discussed in Category-Specific Recalculations The reported overall net GHG source in category 4E has decreased by 0.0 to -0.2 Mt CO2e (3- 6 %) across the time series compared to the previous inventory. The changes were mainly in mineral soil carbon stock change in Settlement remaining Settlement and Land converted to The changes and their justification • Updated EFs from organic soils. An updated (2022) Tier 2 analysis of organic soil emission factors (EFs) from the Defra Peatland Code Project SP0822 was implemented. This update incorporates new UK datasets published since 2019, including data from the UK flux tower network, as well as international data from climatically similar regions. Particulate organic carbon (POC) EFs were updated for all soil categories using an IPCC Tier 1 methodology (IPCC 2014 Appendix Eq.2A.1). • Revisions to organic soil areas. Revisions to the organic soils maps were included from a BEIS Ad-hoc project to edit and check the geometry of the maps and clarify activity data and the assumptions used to create the maps in Evans et al. 2017.Revised deforestation activity data. Deforestation to Settlement area updated to match information reported in the latest Forestry Commission key corporate indicators and to include the data for 2019 and 2020.Changes in emissions are • Minor changes to average biomass densities used for wildfire emission

Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 428 value Units Comment / Justification 4E1 Net carbon stock change in soils - organic soils 3.39 3.21 3.15 2.94 Gg C Revisions to organic soil areas. Updated EFs from organic soils. 4E2.1/4(V) Biomass burning - controlled burning 13.33 57.44 13.34 36.53 Gg C Carbon stock change in living biomass - losses 18.89 77.28 18.89 47.60 Gg C Updated deforestation activity data Net carbon stock change in dead organic matter 4.48 23.39 4.49 16.44 Gg C Net carbon stock change in soils - organic soils 0.01 0.67 0.01 0.58 Gg C Revisions to organic soil areas Updated deforestation activity data Emissions and removals from drainage and rewetting and other management of organic and mineral soils 0.51 0.58 0.53 0.59 Gg CH4 Updated EFs from organic soils. Revisions to organic soil areas. 4E2.1/4(V) Biomass burning - controlled burning 0.15 0.63 0.15 0.40 Gg CH4 Minor changes to average biomass densities used for wildfire emission calculations Emissions and removals from drainage and rewetting and other management of organic and mineral soils 0.001 0.002 0.002 0.002 Gg N2O Revisions to organic soil areas. Updated EFs from organic soils. 4E2.1/4(V) Biomass burning - controlled burning 0.008 0.035 0.008 0.022 Gg N2O Minor changes to average biomass densities used for wildfire emission calculations

Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 429 Category-Specific Planned Improvements The second step in implementing the BEIS-funded Land-Use Tracking project is in progress in Key Categories None identified Completeness No known omissions- areas are reported for land uses with no No emissions or removals are reported in this category in the UK. It is assumed that there are very few areas of land of other types that become bare rock or water bodies, which make up Information on approaches used for representing land areas and on land use databases used for the inventory preparation The approaches used for representing land use areas in the inventory are described in Land-use definitions and the classification system used and their correspondence to the LULUCF categories Other Land is defined as areas that do not fa ll into the other land use categories. The land- cover types in the different data sources that contribute to the Other Land category are described in Annex 3.4.2.1. As described in Section 6.4, areas of inland water exceeding 1km2 are included in 4D Wetlands, but water bodies below this threshold would still be included Category-specific recalculations There are no emissions associated with Other Land and no recalculations. Category-specific planned improvements

Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 430 Emissions sources 4G Harvested Wood Products Emission Factors Country-specific Key Categories 4G Harvested Wood Products – CO2 (L1, T1) Completeness No known omissions Changes to forest planting areas in 4A had a knock-on effect on HWP outputs. Assumed management was revised to best match to the updated data (including new estimates of wood production in Northern Ireland).
HWP stocks result from normal forest management processes (thinning and harvesting) in the Forest Land category and from conversion of Forest Land to Cropland, Grassland or The UK has elected to use the production approach B2 as set out in the IPCC 2006 Guidelines for estimating HWP. The carbon accounting model (CARBINE) is used to calculate the net changes in carbon stocks of harvested wood products (at the product type level), in the same way as it is used to estimate carbon stock changes in 4.A Fores t Land. Changes in carbon stocks from HWP arising from deforestation (conversion of Forest Land to Grassland, Cropland or Settlement) are also estimated using CARBINE. The estimated carbon in harvested wood is split in to harvested wood product classes based on information on wood use from Forestry Commission statistics and the FAO, producing a time series from 1961 to the latest inventory year. A description of the method is outlined in Annex 3.4.10. Data from the Forestry Statistics on consumption of wood products in the UK are then used to disaggregate the HWP into either consumed domestically or exported. This dataset exists from 2002 onwards and the 2002 - 2011 average values are used for 1990-2001. Uncertainties and Time-Series Consistency 4G Harvested Wood Products is estimated to have a combined uncertainty of 15-20% for CO2. These uncertainties are based on an updated uncertainty analysis, broadly following the methodology of the previous uncertainty analysis, but using the updated activity data and methodology for this submission. Details are provided in Annex 3.4.12. Activity data for areas planted and consequently harvested are obtained consistently from the same national forestry sources, which helps ensure time series consistency of estimated removals. Data on the total quantity of softwood and hardwood production are available from 1976 using Forestry Commission reported statistics and from 1961 -1975 using FAO timber production data. Data on the relative proportions of wood from UK sources used f or different harvested wood products is available from 1994 onwards, the proportions prior to 1994 are estimated from FAO data. Data on the export of products is also obtained from national forestry sources, however it is only available from 2002 onwards. The 1990-2001 values are based on the ten year average of the 2002-2011 values. Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 431 A significance analysis has been undertaken for key categories in the LULUCF sector. In Harvested Wood Products HWP Produced and Consumed Domestically is the most significant HWP Produced and Exported 15% 5% Category-Specific QA/QC and Verification This source category is covered by the general QA/QC procedures, which are discussed in Section 1.6. The timber production predicted has been compared to the national timber production statistics produced by the Forestry Commission based on data from sawmills. Category-Specific Recalculations The reported overall net GHG sink in category 4G has increased by between 0.0 and 0.2 Mt CO2e (0 to 6%) across the time series compared to the previous inventory. The changes resulted from updated activity data for affores tation and deforestation , as

Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 432 domestically -485.85 -550.10 -487.83 -510.18 Gg C 4G HWP produced and exported -83.53 -30.46 -83.85 -33.67 Gg C Updated activity data

Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 433 Emissions sources Carbon stock 4A Forest Land, 4B Cropland, 4C Grassland, 4D Wetlands, 4E Settlements 4(II) Emissions and removals from drainage and rewetting and other management of organic and mineral soils (4A Forest Land, 4B Cropland, 4C Grassland) 4(III) Direct N2O emissions from N mineralization (4B Cropland, 4C Grassland, 4E Settlements) 4(V) Biomass Burning (4A Forest Land, 4C Grassland) Methods Tier 1, T2 for organic soils Emission Factors T1 and T2 for direct CO2, CH4 and N2O emissions from organic soils, T1 for other emissions Key Categories None identified Completeness No known emissions Soils in the Isle of Man (IoM) have been split between mineral and organic soils, and emissions from organic soils in the IoM are reported for first time in this submission. GHG emissions and removals from the UK Crown Dependencies (CD) and Overseas Territories (OT) are reported under the relevant categories for the LULUCF sector in the CRF Guernsey and the Isle of Man and the OT s of the Falkland Islands , Cayman Islands and Bermuda. Gibraltar has only one land-use category of Settlement remaining Settlement, with no associated GHG emissions. Annex 3.4.11 provides detailed descriptions of the methods Total LULUCF 0.07 0.11 0.07 0.08 A. Forest Land -0.04 -0.04 -0.04 -0.04 B. Cropland 0.01 0.03 0.01 0.02 C. Grassland 0.00 -0.01 0.00 -0.01 D. Wetlands 0.00 0.00 0.00 0.00 E. Settlements 0.10 0.13 0.10 0.11

Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 434 emissions 0.00 0.00 0.00 0.00 The Forest Land and Grassland categories are net sinks in the OTs and CDs while other land use categories are net sources. The LULUCF sector in the OTs and CDs is a net source in all years. The individual territory trends • Isle of net sink, with net sources in cropland and settlement counterbalanced by net sinks in forest and grassland • small net sink, with net sources in cropland and settlement counterbalanced by net sinks in forest and grassland • moves between being a small net source to a small net sink across the time series, with net sources from cropland and settlements and a net sink in grassland.
• Falkland stable net source 1990-2005, then variable slowly decreasing source due to reduced emissions from cropland • Cayman stable net source 1990 -2006, then a variable net source primarily due to conversion of mangrove (organic) soils to settlement and forest conversion to • small stable net source 1990-2011 due to forest conversion to settlement , becoming a very small net sink from 2012 due to a net sink in settlement. Land cover surveys and agricultural land statistics have been used to compile annual land- use change matrices for the OTs and CDs , which are converted into the UNFCCC land-use change matrices using the 20 year transitio ns (reported in CRF tables 4A -4E in the GBR submission). The total land area of the OTs and CDs is maintained at a constant area by including a small area of unmanaged wetland to account for land reclamation from the sea in The definition of each land category is in accordance with the Agriculture, Forestry and Other Land Use Guidance (IPCC 2006). The Grassland category is used as the ‘buffer’ category to ensure consistency in total land area. Similar climate and land management parameters are assumed as for the UK for Guernsey, Jersey and the Isle of Man . Appropriate parameters for the OTs have been taken from the IPCC 2006 and 2013 guidance (Annex 3.4.11). There is incomplete information on land areas for all territories so l and areas have been interpolated between , or extrapolated from, land area surveys as required. A Tier 1 method has been used to estimate forest carbon stock changes for all territories, using the appropriate emission factors for the climati c region and forest type. The IPCC Tier 1 default factors from the 2006 Agriculture, Forestry, and Land Use (AFOLU) Guidelines and the Tier 1 EFs for mangroves from the 2013 Wetland Supplement have been used to estimate all other emissions and removals. Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 435 The net LULUCF emissions from the OTs and CDs changed compared to the previous inventory, with an reduction of 0. 01 Mt CO 2e in the net source across the time series , predominantly in the Falkland Islands. Carbon stock changes in Cropland in the Falkland Islands have been recalculated to correctly take account of ley grasslands within the Cropland remaining Cropland sub -category. The annual increase in Grassland converted to Settlement in the Falkland Islands from 1991 onwards was reduced to correct a transcription error in the area required per dwelling. For the Isle of Man there were minor changes due to the updated Tier 2 EFs for emissions from organic soils affecting Cropland and Grassland emissions. There were also minor change s due to a recalculation of the indirect N 2O emissions (error correction), new estimates of emissions from domestic peat extraction in the Falkland Islands, and the incorporation of new activity data for Bermuda and Jersey. The UK Government is funding longer-term research into organic soils and emissions in the Falkland Islands. Peat extent and depths have been mapped by the Darwin Plus project DPLUS083, and there are ongoing projects to map undisturbed reference habitats, estimate above-ground biomass stocks and measure CO2 and CH4 fluxes. The Falkland Islands have different peat-forming species to the Northern Hemisphere, and UK Tier 2 emission factors are an imperfect analogue for Falkland conditions, hence the need for additional research. Indirect emissions of N 2O from atmospheric deposition are estimated according to IPCC (2006, equation 11.9) using the default value for EF4 from the 2019 Refinement value for wet climates (0.014 kg N2O-N ) and the fraction of N that is volatilised from inorganic fertiliser N applications to forest land (FracGasF). The change in the EF4 value was implemented for consistency with the value used in the Agriculture sector. The amount of synthetic fertiliser Indirect emissions of N 2O from leaching an d runoff are estimated according IPCC (2006, equation 11.10) using the default value for EF5. The sources of nitrogen considered are synthetic fertiliser application to forest land and direct N 2O emissions from mineralisation soils. The default IPCC (2006) FracLEACH values are used for both sources. There were no significant changes in indirect emissions of N2O in this submission. Indirect N2O emissions from LULUCF activities are estimated to have a combined uncertainty UKCEH has adopted the quality assurance principles set out in the Joint Code of Practice for Research issued by the Biotechnology and Biological Sciences Research Council, the Department for Environment, Food and Rural Affairs, the Food Standards Agency and the Natural Environment Research Council. UKCEH is accredited to ISO9001, the internationally recognised standard for the quality management of businesses. Forest Research are dedicated to delivering world-class scientific research which fully meets our customers’ requirements for quality, timeliness and cost. The quality of science is

Land-Use, Land Use Change and Forestry (CRF Sector 4) 6 UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 436 supported by a Quality Management System (QMS) which ensures that appropriately-trained and qualified personnel use correctly maintained and calibrated equipment and appropriate techniques to produce reliable outputs. Our system of records management enables us to fully demonstrate the quality of our science. Forest Research applies the standards required by the Defra Joint Code of Practice for Research as described above for UKCEH. The Expert Committee on Forest Science provides guidance for the Forestry Commission on the quality and direction of their research. In 2015 a re view of the QA framework and procedures for the full UK inventory was carried out (Hartley McMaster Ltd, 2015). In 2016 all the LULUCF models based in Excel spread spreadsheets were reviewed by Hartley McMaster using a bespoke quality auditing tool developed in Excel. The outputs from this auditing tool resulted in improvements to model documentation and the correction of a few minor errors.
In addition to internal quality assurance procedures the submitted inventory data is also checked by Ricardo Energy & Environment (the national inventory compilers) and the European Environment Agency, as part of the European Union Monitoring Mechanism. A programme of upgrade to the LULUCF models ran from 2016 to 2020. This included verification of model calculations, improvement of documentation, addition of built in QA checks and storage in a version co ntrol repository. A Microsoft Access database is used to compile all the LULUCF inventory numbers and associated data. This database is used to produce consistent outputs for the CRF and other national and international reporting requirements, and for arch iving purposes. In collaboration with Ricardo Energy & Environment, UKCEH has developed a QA/QC plan to standardise and structure the way checks are carried out within the LULUCF inventory. The plan is implemented and revised as required in each inventory cycle. The QA/QC Plan is embedded into all planning, preparation and management activities of the Inventory. The plan sets out five key Data Quality Objectives (DQOs), covering Transparency, Consistency, Completeness, Comparability and Accuracy, which ensure consistency to the IPCC core QA/QC criteria during inventory preparation and

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 437 5A: Solid Waste Disposal on Land 5B: Biological Treatment of Solid Waste Gases Reported CO2, CH4, N2O, NOx, CO, NMVOC, SO2 5A: Solid waste disposal – CH4 (L1, T1, L2, T2) 5B: Biological treatment of waste – CH4 (T1, L2, T2) 5B: Biological treatment of waste – N2O (L2, T2) 5C: Waste incineration – CO2 (L2, T2) 5D: Wastewater handling – CH4 (L1, L2) 5D: Wastewater handling – N2O (L2, T2) Emissions from all sectors are included within UK CRF tables. Completeness No known omissions. A general assessment of completeness for the inventory is Revised estimates for 5D2, industrial wastewater treatment, based upon a new tier 1 approach. Emissions from the waste sector contributed 4.4% to greenhouse gas emissions in 20 21. Emissions consist of CO2, N2O and CH4 from waste incineration, CH4 from solid waste disposal on land, and both CH 4 and N2O from wastewater handling and biological treatment of solid waste. Overall emissions from the waste sector have decreased by 74% since 1990. This is mostly due to the implementation of methane recovery systems at UK landfill sites and reductions in the amount of waste disposed of at landfill sites. UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 438 Waste Related Activities Reported In Other Sectors The waste sector as defined in the 2006 IPCC guidelines relates to emissions from processes associated with the treatment an d disposal of waste. However, if waste or waste -derived products are utilised for another process, emissions associated with this is reported according to the process, and therefore excluded from waste sector reporting. 89 The categories in the Waste sector are explained in the IPCC categories section. UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 439 This section discusses such sources, where those sources are reported in the inventory, and how waste management, waste disposal and waste utilisation interact in the waste, energy and agriculture sectors, and where these are reported in the inventory. UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 440

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 441 of increasing redirecting of waste away from landfill and into either biological treatment of waste or energy from waste; this is further illustrated in the decline in digestible and in quantities of non -degradable waste recycling (such as plastics, glass, and metals) or exported from the UK, as within this context these do not directly generate emissions, and therefore are not explicitly referred to in the inventory. It is expected that at least some of the decline in total waste presented will be due to increase in non-degradable recycling rates. of its combustibility and digestibility. Data are presented only for 2008 onwards as detailed breakdown of waste composition by European Waste Catalogue classification is available for these years only. Note that a large proportion of waste is classified as unspecified mixtures of waste, meaning that there is signi ficant uncertainty as to the classification presented; the 90 Recycling or waste exported are not included, as these do not result in direct emissions occurring in the UK, and therefore the Inventory Agency does not collect estimates of the quantities of waste disposed by these routes

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 442 7.1.1.1 Utilisation of Waste-Derived Biogas A large proportion of methane generated in the anaerobic digestion of biodegradable material, occurring in sewage treatment plants, landfills and sites conducting biological treatment of solid wastes is captured and utilised as a fuel. Fuel use is typical ly on-site with the energy used for other activities on the site, or exported as electricity, but also increasingly, some methane is injected into the national natural gas distribution network for use as a fuel by any user of natural gas. Using methane as a fuel oxidises it, preventing it being released into the atmosphere as methane, instead releasing carbon dioxide and very small quantities of methane and nitrous oxide. The emissions as a result of combustion of biogases for energy is reported in sector 1 A, including biogases that are injected into the national natural gas distribution network. The UK includes emissions from the utilisation of biogases for energy as • Sewage gas and landfill gas used to generate electricity or heat are reported in sector • Other biogases used for energy are reported in sector 1A 2gviii, described in MS 3; • Any biogases that are injected into the natural gas network are reported in energy statistics as a transfer from the renewables balance to the natural gas balance and are therefore included in the inventory as part of natural gas in all downstream uses of natural gas, mostly in various sub-sectors in 1A, described in various sub -sections in Section 3.
Data on the quantity of biogases transferred to natural gas are used to determine the proportion of CO2 emissions from natural gas combustion which are of Note that for all sour ces of biogas, i n the 2022 update of DUKES data reported for 2019 onwards has been reduced significantly. In most cases this creates a divergence in the agreement between DUKES and the NAEI for recent years, and we are engaging with the UK energy stats team to understand how to interpret this. UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 443 wastewater company reported estimates of sewage gas utilisation and UK energy statistics on sewage gas when noting that methane flaring is not a fuel use application, so is excluded from energy statistics. Data are only presented for 2013 onwards, as company reported data in this format is only available for these years; estimates of methane recovered for earlier years are extrapolated based on UK energy statistics. When capture is compared to emission rates, we see implied capture rates of 95-98% in these years, which are a level that would be expected for mature centralised anaerobic digestion. utilisation and UK energy statistics on landfill gas when noting that methane flaring is not a fuel use application, so is excluded from energy statistics. Both UK energy statistics and landfill gas capture estimates for landfill gas utilisation are based on data on electricity generated from engines consuming landfill gas, however, for landfill gas capture estimate s we estimate that these engines improve in efficiency in more recent years, reducing the landfill gas required to generate the electricity observed. The UK Inventory Agency and energy statistics team are aware of this difference and are considering whether these can be aligned. UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 444 manure solid waste anaerobic digestion emissions estimates and UK energy statistics on other biogas use. Data are only presented for 2008 onwards, as all datasets present extremely low values in the early part of the time -series. It is not currently feasible to make more direct comparisons between the waste and energy sector due to the energy sector biogas including biogas derived from animal manures and the non -animal manures solid wastes estimates If comparing non-animal manure solid waste anaerobic digestion emissions estimated to total biogas utilisation, the implied capture rate strictly increa ses from 95% in 2009 to over 99% since 2017. We suspect that the very high implied capture rate in recent years reflects an increasing contribution from manure anaerobic digestion biogas capture and utilisation, which will be included in the methane utilisation data, but not in the non-manure anaerobic digestion

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 445 Information about the methods and data relating to waste incineration is reported under Section 7.4 and emissions are reported under sector 5C. However, if useful energy is extracted from waste incine ration, then for inventory reporting purposes, the activity is considered an energy sector process and emissions are reported under 1A. Due to a ban on the incineration of MSW without energy recovery in 1996 , the quantity of emissions that are The UK includes emissions from the combustion of waste for energy as • Energy from Waste plants are reported in sector 1A1a, described in MS 1; and, • Minerals industries use of waste are reported in sector 1A2f, described in MS 2. 7.1.1.3 Biological Treatment of Waste The reporting of biological treatment (composting or anaerobic digestion) of waste depends on the nature of the waste treated. • For animal manure emissions are reported against 3B, described in Section 5.3; • For sewage, industrial liquid wastes , or sludge derived f rom these wastes that are treated at a wastewater treatment plant emissions are reported against 5D, described • For other solid wastes emissions are reported against 5B, described in Section 7.3. 7.1.1.4 Utilisation of Digestates and Sewage Sludge If digestates or sewage sludge are utilised as a fertiliser, then any e missions from the spreading of these products are reported as an agricultural soils emission, • For digestates spread on agricultural land emissions are reported against 3 D12c, described in Section 5.5.2.3.2; and, 91 i.e., not sewage gas or landfill gas

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 446 • For sewage sludge spread on agricultural land emissions are reported against 3D12b, described in Section 5.5.2.3.1. spread on agricultural land and waste digested or waste sector estimates of sewage sludge disposed to agricultural land. For agricultural waste spreading, a nitrogen balance approach is used to estimate N2O emissions, and hence activity data for those sources are in terms of Nitrogen content instead of total mass. for Digestates and Sewage Sludge 7.1.1.5 Disposal Routes of Sewage Sludge (Other than Utilisation) The reporting of disposal emissions of biologically treated waste depends on the nature of the • For sewage sludge disposed to landfill emissions are reported against 5A, described • For sewage sludge incinerated without energy recovery emissions are reported against 5C, described in Section 7.4. UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 447 sludge disposal to landfill or incineration and the estimates of sewage sludge received at landfills and incineration plants. Note that data for sewage sludge received at landfills are the total weight of matter received, which means it includes a large proportion of water which would not be included in the wastewater data presented in kt tds. Sector Estimates for Sewage Sludge disposal

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 448 Emissions sources Sources included Method Emission Key Categories 5A: Solid waste disposal - CH4 (L1, T1, L2, T2) OT & CD emissions for 5A are included as a separate Completeness No known omissions. A general assessment of completeness for the inventory is The NAEI category “Landfill” maps directly on to IPCC category 5A (Solid Waste Disposal) for methane emissions.
Emissions are reported from Solid Waste Disposal Sites (SWDS – also known as landfills) that started receiving waste in 1980, when legislative changes took effect to improve management of landfill sites, and old unmanaged waste disposal sites that closed prior to 1980. Emissions from the use of landfill gas to generate power are reported in IPCC Estimated emissions from this sector in 2021 were 13.6 Mt CO2e. Emissions have been on a downward trend in almost every year since 1996. In addition to CH 4, anaerobic decomposition also produces an approximately equivalent amount of CO2, further CO2 is produced by other processes. However, as the decaying organic matter originates from biomass sources derived from contemporary crops and forests, we do not need to consider the greenhouse impacts of this carbon dioxide. For this reason, emissions of CO2 from landfills are not estimated as they are considered to be entirely biogenic in origin and therefore not counted toward s the national total as this would introduce a double count with net carbon losses reported in the LULUCF sector (this is also discussed in Section 1.8.2.3). Landfilled Solid Waste also contains fossil-derived organic matter, predominantly in the form of plastics, but these are essentially non-biodegradable under landfill conditions, and so emissions of fossil-derived CO2 from solid waste disposal sites (SWDS) are not considered Non-methane volatile organic compounds (NMVOCs) are also released by SWDS. These are estimated using an emission factor relating the NMVOC to the amount of CH 4 emitted. An emission factor of 0.0036 kg NMVOC/tonne landfill gas was used (Broomfield et al., 2010). The IPPC 2006 Guidelines confirm that nitrous oxide emissions from SWDS are not The amount of methane emitted from landfills depends primari ly on the amount of carbon in biodegradable waste landfilled and how the sites are operated to reduce the escape of the methane produced from such wastes. Policy measures to reduce methane emissions from landfills have focused on both these aspects. Diverting biodegradable waste away from landfill

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 449 avoids the future formation of methane, but landfills continue to produce CH4 for many years from biodegradable waste that has already been deposited. Improving the efficiency of gas capture from landfills results in an immediate reduction in emissions, but is by nature an “end of pipe” solution, which does not itself prevent the formation of methane. In practice, a combination of measures based on both reducing the amount of biodegradable waste landfilled and improving the management of sites have, in the UK, provided the foundations for reducing emissions from this source. These two broad approaches are outlined below. The most important legislative and regulatory measures which have reduced the emissions of methane from UK landfills derive from the 1999 Landfill Directive (1999/31/EC). The requirements of the Directive were transposed into national legislation through the Landfill (England and Wales) Regulations 2002, subsequently amended in 2004 and 2005 to transpose the requirements of Council Decision 2003/33/EC on Waste Acceptance Criteria. The provisions were re -transposed most recently as part of the Environmental Permitting (England and Wales) Regulations 2016, and their ongoing applicability confirmed through the Environmental Permitting (England and Wales) (Amendment) (EU Exit) Regulations 2018. In Scotland, the Landfill Directive is implemented through the Landfill (Scotland) Regulations 2003, as amended, and in Northern Ireland, through the Landfill Regulations (Northern Ireland) 2003. The provisions of the Landfill Directive require reduction of the amount of biodegradable waste landfilled to specific targets and improved landfill design, operation and management in order to reduce release of methane. The EU Waste Framework Directive 2008/98/EC and Landfill Directive 1999/31/EC provides the legislative framework for collection, transport, recovery and disposal of waste. The Waste Framework Directive mandates management of waste according to the waste hierarchy – with the first and preferred method being prevention, followed by reuse, recycling, recovery, and lastly disposal. Defra’s Resources and Waste Strategy published in December 2018 set out how the Government intends to minimise waste, promote resource efficiency and move towards a circular economy in England. Similar approaches are being adopted in the Devolved The UK approach to calculating emissions of methane from landfills uses a “Tier 2” methodology based on national data on waste quantities, composition, properties and disposal practices over several decades. The equations for calculating methane generation use a first- order decay (FOD) methodology (IPCC (2006) p3.6 – 3.12). The IPCC FOD methodology is based on the premise that Dissimilable Degradable Organic Carbon compounds (DDOC; those that can be converted to methane and carbon dioxide) 92 decay under the a naerobic conditions in landfills to form methane, carbon dioxide and a variety of stable decomposition products that remain in the landfill, and represent a sink for carbon. First order means that the rate of reaction is proportional to the amount of reactant (i.e. DDOC) present at any given time. This means that as the reactant is used up, the rate of reaction slows down. In the UK model, the various waste types are allocated to three pools (p) of DDOC that decompose according to their chara cteristic first order rate constant, k p. This parameter defines the proportion of material decomposing per year in each year following disposal. The three pools are described as Rapidly, Moderately, and Slowly Decomposing Organics (RDO, MDO and SDO, respectively). Allocation of DDOC in waste materials to these pools was described in a report produced by Eunomia Consulting and Research (2011) and updated for the 2013 and 2014 inventories. Fats, sugars and proteins are assigned to the rapidly 92 DDOC is the amount of degradable organic carbon (DOC) that is converted (i.e. dissimilated) to methane and carbon dioxide under landfill conditions. DDOC = DOC x DOCF where DOCF is the fraction of DOC that

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 450 degrading pool (RDO), lignin to the slowly degrading pool (SDO) and cellulose, hemicelluloses and remaining compounds are allocated to the moderately degrading pool (MDO).
Methane generation is calculated using the methodology set out in the IPCC 2006 Equations 3.1 to 3.6. The equations set out below are copied directly from the IPCC 2006 Guideline. • Equation 3.1 represents the overall approach of calculating methane formation for each year, subtracting the quantity of methane collected, and allowing for the quantity of methane oxidised in the Solid Waste Disposal Site (SWDS) cover layer. This equation is used explicitly in the UK inventory as set out in IPCC (2006). The IPCC 2006 Guideline default value of 0.1 is used for OX T, the proportion of methane oxidised on passing through the landfill surface. • Equation 3.2 enables the mass of DDOC deposited to be calculated from the mass of waste deposited, the fraction of Degradable Organic Carbon (DOC) in the waste, and the methane correction factor. This equation is applied to individual waste streams in the UK inventory based on their lignin and non -lignin carbon contents (rather than Research, 2011). S eparate Methane Correction Factors are applied to waste deposited in unmanaged sites prior to 1980, and waste deposited in managed sites from 1980 onwards (see below). These are taken from the IPCC 2006 Guidelines. The following values are used for DOC (derived from Eunomia Consulting and Research, 2011) (there is some overlap b etween categories because of historical definitions used to characterise residual waste landfilled): Paper 8% 3% 21% 0% 0% 0% 0% 0% 0% 0% Card 8% 3% 20% 0% 0% 0% 0% 0% 0% 0% Nappies 0% 0% 7% 0% 0% 0% 0% 0% 0% 0% Textiles and footwear 0% 5% 5% 0% 0% 0% 0% 0% 0% 0% Miscellaneous combustible 0% 9% 8% 0% 0% 0% 0% 0% 0% 0% Wood 14% 4% 14% 0% 0% 0% 0% 0% 0% 0% Food 1% 1% 3% 2% 1% 3% 2% 2% 0% 0% Garden 6% 3% 4% 0% 0% 1% 0% 0% 5% 0% Soil and other organic 0% 0% 0% 0% 0% 0% 0% 0% 0% 0%

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 451 Furniture 1% 4% 4% 0% 0% 0% 0% 0% 0% 0% Mattresses 0% 5% 5% 0% 0% 0% 0% 0% 0% 0% Non-inert Fines 0% 7% 6% 0% 0% 0% 0% 0% 0% 0% Inert 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% Commercial 1 0% 2% 19% 0% 0% 0% 0% 0% 0% 0% Paper and Card 8% 3% 21% 0% 0% 0% 0% 0% 0% 0% General industrial waste 1 0% 2% 19% 0% 0% 0% 0% 0% 0% 0% Food and Abattoir 1% 1% 1% 5% 1% 1% 2% 0% 0% 0% Food effluent 0% 9% 1% 0% 0% 0% 0% 0% 0% 0% Construction and Demolition 0% 3% 2% 0% 0% 0% 0% 0% 0% 0% Miscellaneous processes 1 0% 4% 3% 0% 0% 0% 0% 0% 0% 0% Other waste 1 0% 9% 8% 0% 0% 0% 0% 0% 0% 0% Sewage sludge 0% 2% 2% 0% 0% 0% 0% 0% 0% 0% Textiles / Carpet and Underlay 0% 5% 5% 0% 0% 0% 0% 0% 0% 0% Sanitary 0% 0% 7% 0% 0% 0% 0% 0% 0% 0% Other 1 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% Note 1: This category no longer used in waste descriptions These values are calculated by multiplying the dry matter content of each waste component o Hemicellulose 44.6% dry matter o Readily soluble 45.0% dry matter The following values are used for moisture content and DOC f (Eunomia Consulting and Textiles and footwear 20% 5.0% 65.0% Miscellaneous combustible 20% 5.0% 65.0%

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 452 Soil and other organic 30% 5.0% 65.0% Non-inert Fines 40% 0.0% 50.0% General industrial waste 1 37% 5.0% 65.0% Food and Abattoir 70% 15.0% 70.0% Construction and demolition 30% 5.0% 65.0% Miscellaneous processes 1 20% 5.0% 65.0% Textiles / Carpet and Underlay 20% 5.0% 65.0% Note 1: This category no longer used in waste descriptions Guidelines. However, the IPCC Tier 1 model contains default DOC values for some waste 7.3. However, the sensitivity test set out in Section 7.2.5 indicates that the UK values are more representative of wastes landfilled in the UK Disposable nappies 0.07 0.24 29% The values used for the MCF are in accordance with the IPPC 2006 default values for managed and unmanaged sites (see below). Equation 3.3 is a calculation of methane generation potential from the mass of DDOC deposited, and the fraction of methane in landfill gas. This equation is used in the UK inventory as set out in IPCC (2006). Following a review of data on the composition of landfill gas, the fraction of methane in landfill gas as formed in UK landfill sit es is assumed to be 50%, the default value given in the 2006 IPCC Guidelines. UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 453 Equation 3.4 describes the accumulation of DDOC in the landfill site, accounting for new material deposited, and material which decomposes in each year. This equation is used in the UK inventory as described in IPCC (2006) Section 3A1.4, by carrying out a calculation of the mass of rapidly, medium and slowly -decaying carbon present in the landfill in each year, o The mass of DDOC remaining from the preceding year o Plus the mass of DDOC landfilled in that year o Minus the mass of DDOC removed due to decomposition in that year The calculation has been amended to account for the commencement of decomposition during the year of deposition, as described in IPCC (2006) Equation 3A1.12. Equation 3.5 describes the rate at which DDOC is removed from landfill sites in each year by decomposition and formation of methane and carbon dioxide in landfill gas . The calculation has been amended to account for the commencement of decomposition during the year of deposition, as described in IPCC (2006) Equation 3A1.13.
The decomposition rate constants used for rapidly, medium and slowly decaying wastes are for a wet boreal climate. The average of two default values for slowly decaying waste was used. These are allocated to the organic components of waste as o Rapidly decaying Starch, Sugar, Fat, Proteins, Fibre, Readily soluble o Medium decaying Hemicellulose, Cellulose o Slowly decaying Lignin Equation 3.6 is a calculation of methane generated from the mass of DDOC which decomposes during any given year, and the fraction of methane in landfill gas. This equation is used in the UK inventory as set out in IPCC (2006). As described for Equation 3.3, the fraction of methane in landfill gas as formed in UK landfill sites is assumed to be 50%. The values used for DOC and DOC f for different material types, and the composi tion of

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 454 The total methane generated in each inventory year is determined by summing the quantity of methane emitted over all waste types, all three decomposition pools, all landfill types, and all years in which the waste is landfilled. A Methane Correction Factor (MCF) is used as a multiplier on methane formation to reflect the fac t that shallow or unmanaged disposal sites do not develop extensive anaerobic conditions typical of modern landfills and hence a proportion of waste decays aerobically and does not produce methane. For modern landfills, the MCF term is given the value of 1 (IPCC All solid waste disposal sites in the UK that have received biodegradable wastes since 1980 have been required to adhere to a number of regulations are classed as landfills and assigned a MCF value of 1. MCF has been assigned a value of 0.6 for old closed landfills that operated A spreadsheet model system known as MELMod was used to carry out these calculations from 2008 (Brown et al., 2008). Separate calculations are carried out for England, Scotland, Wales and Northern Ireland. In 2010, the UK gove rnment commissioned further work to update the activity data and emission factors for landfill methane (Eunomia Consulting and Research, 2011), which was peer reviewed by independent experts from academia, industry, regulators and consultants in 2010. The principal changes to the input data at that time were summarised in the 2011 NIR submission for the 1990-2009 inventory. Further details on data sources and rationale are given in Eunomia’s report. In the 2017 submission, the UK implemented for the first time a revised set of input data and parameters for the inventory model calculations, whilst not altering the methodology itself. This followed research to access and use more data from within ind ividual Devolved Administrations (Scotland, Wales and Northern Ireland) and England, in order to better -reflect differences in waste management around the UK, as it is an area of devolved policy. Records of individual waste consignments treated and disposed, together with European Waste Category (EWC) codes are compiled by the regulatory authorities in the Devolved • Data on waste consignments landfilled in England for the period 2006 to 20 21 are published by the Environment Agency. • Data on waste consignments landfilled in Scotland for the period 2005 to 20 21 are published by the Scottish Environmental Protection Agency. • Data on waste consignments landfilled in Wales for the period 2006 to 20 21 are published by Natural Resources Wales. • Data on waste consignments landfilled in Northern Ireland for the period 2008 to 2021 were provided by the Northern Ireland Environment Agency. This information is considered to be of good quality. The composition of waste landfilled was evaluated by allocating EWC codes to the categories used in the UK model, as set out in For years prior to 2005-2008, the quantities of waste landfilled and its composition were taken from a report compiled and peer-reviewed on behalf of the UK Government (Eunomia, 2011). 7.2.3.1 Methane recovery from modern landfills Landfill operators are required under their permit conditions to control the release of landfill gas. For large landfills containing biodegradable wastes, this requires the use of impermeable liners and cover material, and gas extraction systems. These typ ically consist of a system of gas wells (perforated pipes sunk into the waste) connected to a network of gas collection

UK NIR 2023 (Issue 1) Ricardo Energy & Environment Page 455 pipes. Suction is applied to the gas wells, resulting in a slight negative pressure sufficient to draw out the landfill gas but not enou gh to draw excessive air into the waste. Air ingress is avoided, as it can result in aerobic decomposition of the waste, which produces considerable heat, and may lead to the waste catching fire, as well as shutting off methane formation. The landfill gas collected is normally used to generate electricity on a commercial basis. Where this is not practicable, gas collected can be burnt in flares. In either case, the net effect of the combustion process is to convert the methane to carbon dioxide. The carbon dioxide so produced is not taken into further consideration for inventory purposes as it is considered to be entirely biogenic in origin. Small quantities of other GHGs (methane and nitrous oxide) are emitted from landfill gas use for power generation, and are included in Section 1.A.1.a. The key factors in determining methane emissions are estimates of the quantity of methane generated, and information on the amount of methane collected, either for utilisation or flaring. Data on utilisation is available and of good quality (see Section 7.2.3.2), but recent analysis indicates that data on flaring prior to 2009 is either unavailable or only accessible at disproportionate cost. The current inventory uses operator-provided data on the quantities of gas collected and burnt in landfill gas flares (see Section 7.2.3.3). No gas collection is assumed to be carried out at old pre-1980 closed sites.