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TABLE 4-10
SCALING FACTORS FOR METHANE EMISSIONS FOR RICE ECOSYSTEMS RELATIVETO CONTINUOUSLY FLOODED FIELDS(WITHOUT ORGANIC AMENDMENTS)
Category

Sub-Categorya

Scaling Factors (relative toemission factors forcontinuously flooded fields)

None

0

UplandLowland

Irrigated

Continuously flooded
Intermittently
floodedb

RainfedDeep water

1.0

Singleaeration

0.5 (0.2-0.7)

Multipleaeration

0.2 (0.1-0.3)

Flood prone

0.8 (0.5-1.0)

Drought prone

0.4 (0-0.5)

Water depth 50-100 cm

0.8 (0.6-1.0)

Water depth > 100 cm

0.6 (0.5-0.8)

a other rice ecosystem categories, like swamps, inland saline or tidal wetlands may be discriminated within each sub-category
according to local emission measurements.
b defined as > 3 days aeration during the vegetative period.

Note: For irrigated and continuously flooded, lowland rice ecosystems, the default seasonally integrated methane emission is
20 g/m2 (see Table 4-11) for soils ‘without organic amendments’. For conversion to methane emissions from soils ‘with organic
amendments’, apply a default correction factor of 2 (Range 2-5) to the corresponding rice ecosystem for the ‘without organic
amendment’ category.

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TABLE 4-11
SEASONALLY INTEGRATED METHANE EMISSION FACTORS FOR CONTINUOUSLY FLOODED RICE WITHOUTORGANIC FERTILISER IN VARIOUS LOCATIONS OF THE WORLDCountry

Seasonally Integrated Emission
Factor, EFa(g/m2)

Literature/Remarks

Australia

22.5

NGGIC, 1996

China

13 (10-22)

Wassman et al., 1993aIndia

10 (5 - 15)

Mitra et al., 1996
Parashar et al., 1996

Indonesia

18 (5 - 44)

Nugroho et al., 1994a,b

Italy

36 (17-54)

Schütz et al., 1989a

Japan

15

Minami, 1995

Republic of Korea

15

Shin et al., 1995

Philippines(25 - 30)

Neue et al., 1994; Wassman et al.,
1994

Thailand16 (4 - 40)

Towpryaoon et al., 1993

USA (Texas)

25 (15 - 35)

Sass and Fisher, 1995

Arithmetic Meanb

20 (12-28)-

a It is recognised that the emission factors presented in Table 4-11 will need to be periodically updated as better data become
available. However, this dataset represents the best available information at the time of compilation.
b The arithmetic mean of the seasonally integrated emission factor, EF, is derived from the values shown in Table 4-11. The
range of emission factors is defined as the standard deviation about the mean.

4.22

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4.4

Prescribed Burning of Savannas
4.4.1 Introduction
Savannas are tropical and subtropical formations with continuous grass coverage.
The growth of savannas is controlled by alternating wet and dry seasons: most of
the growth occurs during the wet season. Man-made and/or natural fires
frequently occur during the dry season, resulting in nutrient recycling andregrowth. Large scale burning takes place primarily in the humid savannas
because the arid savannas lack sufficient grass cover to sustain fire. Savannas areburned every one to four years on average, with the highest frequency in thehumid savannas of Africa.
The burning of savannas results in instantaneous emissions of carbon dioxide.
However, because the vegetation regrows between the burning cycles, thecarbon dioxide released to the atmosphere is reabsorbed during the next
vegetation growth period. Therefore, this Workbook assumes that CO2 netemissions are zero.
The burning of savannas also releases gases other than CO2, including
methane, carbon monoxide, nitrous oxide and oxides of nitrogen. Unlike
CO2 emissions these are net anthropogenic emissions and should be
accounted for.

DEGRADED SAVANNAS
Although the default assumption isthat biomass burned on savannas
regrows in a short period, this may
not always be the case. Sometimes
savannas are burned too often, orfor other reasons fail to recovercompletely. Over time savannas candegrade significantly as a result of
human intervention. In this casethere will be a long-term loss ofcarbon in aboveground biomass andsoils. If this is occurring, the annual
carbon loss should be accounted for,if possible, in addition to theinformation requested in the
Workbook.

4.4.2 Data sources
There are no routinely published data on the amount of savanna burned, butseveral assessment papers have been published. The FAO Forest Resource
Assessment 1990: Tropical Countries (FAO 1993) provides country estimatesof savanna (grassland) area and the Greenhouse Gas Inventory Reference Manual
provides additional references.

4.4.3 Methodology
The non-CO2 trace gas emissions from savanna burning may be estimatedthrough a series of simple calculations using either locally available data or
defaults provided in the tables in this Workbook.
First the quantity of biomass that actually burns is calculated by multiplying
area of savanna burned by average biomass density and by the fraction of
exposed biomass which actually burns.
Second, carbon released is calculated multiplying quantity of biomass burned
by fraction oxidised and then by carbon fraction.
The second calculation can be greatly improved by first dividing the quantityof biomass burned into living and dead fractions. The calculation is thencarried out for each of these fractions using different fractions oxidised andcarbon contents for the living and dead fractions.

Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories:

NON-METHANE VOLATILEORGANIC COMPOUNDSNMVOCs are emitted in significant
quantities from biomass burning.
These emissions should be estimatedusing the same approach provided
for other non-CO2 gases. However,the default information has not yet
been developed to include this classof gases in the Workbook. This is anarea to be considered in future
improvements to the Guidelines.

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Third, several ratios are applied to total carbon released to derive estimatesof non-CO2 trace gas emissions, as follows:

FRACTIONSIn order to determine the amount ofsavanna biomass that actually oxidises
to release carbon to the atmosphere,
several fractions must be applied
sequentially.
To start with, thequantity of biomass exposed to fire is
calculated by multiplying the area ofsavanna burned in the inventory yearby the average biomass density (intonnes of dry matter per hectare).
The fractions are then applied asfollows.
Fraction which Actually Burns
Under
normalopen
burning
conditions all biomass in each hectare
does not actually burn. The Fraction
which Actually Burns (generally 0.80 0.85 but may be higher in very dry
regions) is applied to derive thekilotonnes of dry matter which
actually burn.

•a nitrogen-carbon ratio is applied to estimate total nitrogen content•

ratios for CH4 and CO as fractions of total carbon•

ratios of N2O and NOx as fractions of total nitrogen

The resulting estimates of emissions are converted to total weight (i.e., fromCH4 as C to CH4 total) using standard factors.
One country may possess more than one type of savanna with different
characteristics; burns may vary in efficiency; and burns may take place at
different times during the dry season, causing the burning to vary with thestate of the vegetation (such as the moisture content and whether thebiomass is alive or dead).
If data are locally available savanna burned should be subdivided into relevant
subcategories reflecting these variations and entered into the worksheet. If
you are relying on the default values in this Workbook you will only be able
to carry out calculations at a national level.

Completing the Worksheet

Fraction OxidisedThis next fraction to be applied
expresses the biomass that oxidises.
Not all of the burning biomass
oxidises - a small fraction may remain
as charcoal. The fraction oxidised isusually 0.8 to 1.0.
Carbon Fraction
The last fraction to be applieddetermines the amount of carbon
that is released from the fraction of
biomass which has oxidised.

4.24

STEP 1 ESTIMATING TOTAL BIOMASS THATACTUALLY BURNS
Use WORKSHEET 4-3 PRESCRIBED BURNING OF SAVANNAS at the end of thismodule to record inventory data. You should do this for a single national
average category or subdivide if data are locally available for each relevant
subcategory of savanna.
1

For each category of savanna, enter the Area Burned (in kilohectares) incolumn A.
If possible use locally available data for hectares of savanna burned
annually. If this is not possible, a crude default approach is to determine
the total savanna area and multiply by typical regional defaults forpercentage burned annually from Table 4-12 (below).

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TABLE 4-12
REGIONAL SAVANNA STATISTICS
RegionFraction of
Total Savanna
BurnedAnnually

Aboveground
Biomass Density

Fraction of
Biomass Actually
BurnedFraction ofAboveground
Biomass thatis Living

Tropical America

0.50

6.6 ±1.8

Tropical Asia

0.50

4.9

Tropical Africa

0.75

6.6 ±1.6

Sahel zone

0.05-0.15

0.5-2.5*

0.95

0.20

North Sudan zone

0.25-0.50

2-4*

0.85

0.45

0.25-0.50

3-6*

0.85

0.45

Guinea zone

0.60-0.80

4-8*

0.90-1.0

0.55

Australia

0.05-0.70

2.1-6South Sudan zone

(t dm/ha)Regional defaults are for seasonal average densities which should be used for emissions calculations.
Values marked with * are maximum, season end densities which are appropriate defaults for these very
dry sub-regions.
Note: These are ecological zones that do not correspond directly to areas with political boundaries of thesame name. For example, the North and South Sudan Zones include countries other than Sudan and run
East-West across the African continent.
See the Greenhouse Gas Inventory Reference Manual for sources of these figures.

2

For each category of savanna, enter the Biomass Density of the Savanna (intonnes of dry matter per hectare) in column B. Table 4-12 provides
available summary information by region which can be used as default data.

3

Multiply the Area Burned by the Biomass Density of the Savanna to give
the Total Biomass Exposed to Burning (in gigagrams of dry matter,
which is the same as kilotonnes dm). Enter the result in column C.

4Enter the Fraction of Biomass Actually Burned in column D.
Use locally available data if available. You can use a general default figurein the range 0.80 - 0.85. Some specific values for African sub-regions
are given in Table 4-12.

5Multiply Total Biomass Exposed to Burning (column C) by the Fraction
Actually Burned (column D) to give the Quantity Actually Burned.
Enter the results in column E.

CATEGORIES OF SAVANNAS
A number of users of the draft
Guidelines, particularly in Africa, havesuggested that savannas should be
divided into woody savannas andgrasslands if possible. For woody
savannas, the aboveground biomass
densities prior to burning would behigher and the fraction oxidisedshould be lower, as much of thestanding woody biomass would not
be burned. Other subcategories byregion, time of burning, etc. may also
be useful.

STEP 2 ESTIMATING THE PROPORTIONS OF
LIVING AND DEAD BIOMASS
1Enter the Fraction of Living Biomass burned in column F.
Some default figures are in Table 4-12 for specific sub-regions in
Africa. In other regions users must provide these values. If noinformation is available, users can do the calculation using "combined
values" (see margin box: categories of savannas).

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AGRICULTURE

2

Multiply the Quantity Actually Burned by the Fraction of Biomass
Living to give the quantity of Living Biomass Burned (in gigagrams ofdry matter). Enter the result in column G.

3

Subtract the Living Biomass Burned from the Quantity of Biomass
Actually Burned to give the quantity of Dead Biomass Burned (ingigagrams of dry matter). Enter the result in column H.

STEP 3 ESTIMATING THE TOTAL CARBONRELEASED
1COMBINED VALUES
From this point on in the worksheet,each original category is split into twoparts - living and dead - for whichcalculations are made separately. Eachrow in the worksheet splits into living
and dead rows for columns I through J.
If users are not able to report living anddead fractions, the default calculation
can be done using "combined" values
from Table 4-13.

4.26

For each category of savanna, enter the Fraction Oxidised for living
and dead biomass. Enter the results in the appropriate boxes incolumn I. Default figures are in Table 4-13.

TABLE 4-13
GENERAL DEFAULT VALUES
Fraction
Oxidised

CarbonFraction

LivingFraction

0.80

0.45

Dead
Fraction

1.0

0.40

Combined

0.90

0.45

2

For each category of savanna multiply the Living Biomass Burned by
the Fraction Oxidised for living biomass. Also, multiply Dead Biomass
Burned by the Fraction Oxidised for dead biomass. Enter the results,
in gigagrams of dry matter, in the appropriate boxes in column J.

3For each category of savanna, living and dead, enter the Carbon
Fraction (of dry matter) of living and dead biomass in column K.
Default figures are in Table 4-13.

4Multiply the Total Biomass Burned by the Carbon Fraction for eachcategory of savanna, living and dead, to give the Total Carbon
Released. Enter the results in column L in gigagrams of carbon.

5

Add the totals in column L and enter the result in the Total box at thebottom of the column. Carry the result forward to column L at thestart of sheet 3 on the next page.

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STEP 4 ESTIMATING NON-CO2 TRACE GASEMISSIONS FROM SAVANNA BURNING
1Enter the Nitrogen-Carbon Ratio in column M.
If no data specific to biomass type are locally available, use the general
default value for savannas, which is 0.006.

2

Multiply Total Carbon Released (column L) by the Nitrogen-Carbon
Ratio to give the Total Nitrogen Content (in gigagrams of Nitrogen).
Enter the result in the appropriate box in column N.

3

For each gas - methane (CH4), carbon monoxide (CO), nitrous oxide (N2O)
and nitrogen oxides (NOx) - enter an Emission Ratio in column O.
Table 4-14 shows the default ratios.
TABLE 4-14
EMISSION RATIOS AND RANGES FOR SAVANNA BURNINGCALCULATIONS
CompoundDefault value

Range

CH4

0.004

0.002 - 0.006

CO

0.06

0.04 - 0.08

N 2O

0.007

0.005 - 0.009

NOx

0.121

0.094 - 0.148

Note: Ratios for carbon compounds are mass of carbon released as CH4 or
CO (in units of C) relative to mass of total carbon released from burning(in units of C); those for the nitrogen compounds are expressed as theratios of mass of nitrogen compounds released relative to the total mass ofnitrogen released from the fuel.
See the Greenhouse Gas Inventory Reference Manual for sources.

4

Multiply Total Carbon Released (column L) (for CH4 and CO), or Total
Nitrogen Content (column N) (for N2O and NOx) by the emissions
ratios in column O to give the total emissions for each gas. Enter the
results in column P.

STEP 5 CONVERT EMISSIONS OF CARBON
AND NITROGEN INTO METHANE, CARBONMONOXIDE, NITROUS OXIDE ANDNITROGEN OXIDE EMISSIONS.
1 Multiply the emissions of each gas expressed as C or N by theappropriate Conversion Ratio2 in column Q to give the Emissions fromSavanna Burning for each gas emitted. Enter the results in column R.

2 The molecular weight ratios given above for the emitted gases are withrespect to the weight of nitrogen or carbon in the molecule. Thus for N2O
the ratio is 44/28 and for NOx it is 46/14. NO2 has been used as thereference molecule for NOx.

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4.5

Field Burning of Agricultural
Residues
4.5.1 Introduction
Large quantities of agricultural residues are produced from farming systems
world-wide. Burning of crop residues in the fields is a common agricultural
practice, particularly in developing countries. It has been estimated that asmuch as 40 per cent of the residues produced in developing countries may
be burned in fields, while the percentage is lower in developed countries. It
is important to note that some crop residues are removed from the fields
and burned as a source of energy, especially in developing countries.
Emissions from this type of burning are calculated in the Energy module ofthis Workbook. Users should ensure that residue burning is properly
allocated to these two components and not double counted.
This submodule deals exclusively with emissions of methane, carbon
monoxide, nitrous oxide and nitrogen oxides from crop residues. In thisWorkbook, field burning of crop residues is not treated as a net source ofcarbon dioxide because it is assumed that the carbon released to theatmosphere is reabsorbed during the next growing season. However crop
residue burning is a significant net source of emissions of methane, carbon
monoxide, nitrous oxide and nitrogen oxides.

4.5.2 Data sources
Annual crop production statistics by country for most of the crops fromwhich residues are burned may be found in FAO Production Year Books(e.g., FAO, 1991). Crop specific data for each country on ratios of residue
to crop production, fraction of residue burned, dry matter content ofresidue and carbon and nitrogen contents of residue should be provided byindividual countries if available. Table 4-15 Selected Crop Residue Statistics
shows default data for crop residues.

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TABLE 4-15
SELECTED CROP RESIDUE STATISTICS
Product

Residue / Dry Matter Carbon
Crop Ratio Fraction
Fraction

NitrogenCarbon
Ratio

Wheat

1.3

0.78-0.88

0.4853

0.012

Barley1.2

0.78-0.88

0.4567Maize

10.30-0.50

0.4709

0.02

Oats

1.3

Rye

1.6

Rice

1.4

0.78-0.88

0.41440.014

Millet1.4

0.016

Sorghum

1.4

0.02

Pea

1.5

Bean

2.1

Soya

2.1

Potatoes

0.4

0.30-0.60

0.4226

Feedbeet

0.3

0.10-0.20a

0.4072a

Sugarbeet

0.2

0.10-0.20a

0.4072aJerusalem artichoke

0.8

Peanut1

0.05

Note: Crop statistics in this table are not complete. For values not specified you
should use values for the most similar crop type as defaults.
See the Greenhouse Gas Inventory Reference Manual for sources.
a These statistics are for beet leaves.

Completing the Worksheet
STEP 1 CALCULATING THE AMOUNT OFRESIDUE
Use WORKSHEET 4-4 FIELD BURNING OF AGRICULTURAL RESIDUES to enter
data for this module.
1 Specify the important crops which produce residues burned in fields andenter these as categories on the Worksheet.
2 For each type of crop, enter Annual Production in gigagrams, which isthe same as kilotonnes, of crop product in column A.

USING THE WORKSHEET•

Copy the Worksheet at the endof this section to complete theinventory.

•

Keep the original of theWorksheet blank so you canmake further copies if necessary

3 Enter the Residue to Crop Ratio for each crop type in column B. Use
Table 4-15 above if there are no local statistics.
4 Multiply the Annual Production of each crop by the Residue to Crop
Ratio to give the Quantity of Residue. Enter the result in column C.

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STEP 2 ESTIMATING THE AMOUNT OF DRYRESIDUE
1 Enter Dry Matter Fraction for each crop type in column D.
Default values for some crop types are shown in Table 4-15.
2 Multiply the Quantity of Residue by the Dry Matter Fraction to give theQuantity of Dry Residue in gigagrams of dry matter. Enter the result incolumn E.

STEP 3 ESTIMATING TOTAL BIOMASSBURNED
1 Enter the Fraction Burned in Fields for each crop type in column F.
Values should reflect an average of practices for the individual country.
No default data are available.
2 Enter the Fraction Oxidised for each crop type in column G (default
value 0.90).
3 Multiply the Quantity of Dry Residue by the Fraction Burned in Fields
and the Fraction of Biomass Oxidised to give the Total Biomass Burned(in gigagrams of dry matter). Enter the result in column H.

STEP 4 CALCULATING THE TOTAL CARBONRELEASED
1 Enter the Carbon Fraction of each residue in column I.
Default values for some crop types are shown in Table 4-15. If no otherinformation is available, use the general default for live biomass, which is 0.5.
2 Multiply the Total Biomass Burned by the Carbon Fraction of eachresidue to give the Total Carbon Released in gigagrams of carbon. Enterthe results in column J.
3 Add the totals for each crop type in column J and enter the result in the
Total box at the bottom of the column.

STEP 5 ESTIMATING TOTAL NITROGENRELEASED
1 Enter the Nitrogen-Carbon Ratio for each crop type in column K.
The general default Nitrogen-Carbon ratio for crops is 0.01- 0.02. Some
specific values for individual crops are given in Table 4-15.
2 Multiply the Total Carbon Released (column J) by the Nitrogen-Carbon
Ratio (column K) to give the Total Nitrogen Released. Enter the result
in column L.
3 Add the Total Nitrogen Released for each crop type and enter the resultin the Total box at the bottom of column L.

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STEP 6 ESTIMATING NON-CO2 TRACE GASEMISSIONS
1 Enter Emission Ratios in the relevant boxes in column M. Table 4-16
shows default emission ratios and ranges.

TABLE 4-16
DEFAULT EMISSION RATES FOR AGRICULTURAL RESIDUEBURNING CALCULATIONS
RatiosGas

Default

Range

CH4

0.005

0.003-0.007

CO

0.06

0.04-0.08

N2O

0.007

0.005-0.009

NOx

0.121

0.094-0.148

Note: Ratios for carbon compounds are mass of carbon released as CH4 or
CO (in units of C) relative to mass of total carbon released from burning (inunits of C); those for the nitrogen compounds are expressed as the ratios ofmass of nitrogen compounds released relative to the total mass of nitrogen
released from the fuel.
See the Greenhouse Gas Inventory Reference Manual for sources.

2 Multiply Carbon Released (Total from column J) by the Emission Ratios
for CH4 or CO (column M) to give the Emissions of Carbon as methaneand carbon monoxide. Enter the results in the appropriate boxes incolumn N.
3 Multiply Nitrogen Released (Total from column L) by the Emission Ratios
for N2O or NOx (column M) to give the Emissions of Nitrogen as
nitrous oxide and nitrogen oxides. Enter the results in the appropriate
boxes in column N.
4 For each gas, multiply by the Conversion Ratio3 in column O to give theamount of Emissions from Burning Agricultural Residues. Enter the
results, in gigagrams of each gas, in the appropriate boxes in column P.

3 The molecular weight ratios given above for the emitted gases are withrespect to the weight of nitrogen or carbon in the molecule. Thus for N2O
the ratio is 44/28 and for NOx it is 46/14. NO2 has been used as thereference molecule for NOx.

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4.6

Agricultural Soils
4.6.1 Introduction
Adequate information exists to calculate N2O emissions from agricultural
systems including (1) direct emissions of N2O from agricultural soils(including glasshouse systems farming and excluding effects of grazing
animals) (2) direct soil emissions of N2O from animal production and (3)indirect emissions of N2O from nitrogen used in agriculture. The
calculations can be performed in 9 steps in Worksheet 4-5.

4.6.2 Data Sources
All input data can be obtained from FAO databases.
The following input data are needed:• Total use of synthetic fertiliser in country (NFERT, in kg N/yr).
• Number of livestock in country for the following categories: non-dairy
cattle, dairy cattle, poultry, sheep, swine and other animals; N(T).
• Dry pulses and soybeans produced in country (CropBF, in kg/yr).
• Dry production of other crops in country (Crop0, kg/yr).
• Area of cultivated organic soils (Histosols) in country (FOS, ha).

4.6.3 Methodology
Total N2O–N emissions from a country (kg N2O–N/yr) are:

N2O = N2ODIRECT + N2OANIMALS + N2OINDIRECT

Completing the Worksheets
Use WORKSHEET 4-5, AGRICULTURAL SOILS at the end of this module torecord the data.
ESTIMATING DIRECT NITROUS OXIDEEMISSIONS FROM AGRICULTURAL FIELDSSTEP 1 AMOUNT OF N INPUT
1 Calculation of synthetic fertiliser use (FSN)The Worksheet calculations require the total synthetic fertiliser, FSN, used in
the country excluding emissions of NH3 and NOx (FSN). This can becalculated from the following equation.

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EQUATION 1
FSN = NFERT x (1-FracGASF)
where:
NFERT=

total use of synthetic fertiliser in country (kg N/yr);

FracGASF=

fraction of total synthetic fertiliser nitrogen that isemitted as NOx + NH3 (kg N/kg N) (see Table 4-17).

Enter FSN in Worksheet 4-5, sheet 1 in column A.

2 Calculation of nitrogen from animal waste (FAW)
The data needed are: livestock numbers in country for the following
categories: non-dairy cattle, dairy cattle, poultry, sheep, swine and otheranimals, N(T).
Using nitrogen excretion factors as listed in Table 4-6, total nitrogenexcretion by livestock can be calculated from livestock numbers. Table 4-7
shows the percentage of the manure-N used as fuel (FracFUEL), and fromgrazing animals (Pasture range and Paddock) (FracGRAZ).
EQUATION 2
FAW = (Nex (1-(FracFUEL + FracGRAZ + FracGASM))

EQUATION 3
Nex = ∑ [N(T) x Nex(T)]

EQUATION 4
Nex(AWMS) = ∑ [N(T) x Nex(T) x AWMS(T)]where:AWMS(T)=

fraction of Nex(T) that is produced in the different
distinguished animal waste management systems incountry (from Tables 4-6 and 4-7);

FAW=

manure nitrogen used as fertiliser in country, corrected
for NH3 and NOx emissions and excluding manure
produced during grazing (kg N/yr);

FracFUEL=

fraction of livestock nitrogen excretion contained in
excrements burned for fuel (kg N/kg N totally
excreted);

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FracGRAZ=

fraction of livestock nitrogen excreted and deposited
onto soil during grazing (kg N/kg N excreted); country
estimate;

FracGASM=

fraction of total nitrogen excretion that is emitted as
NOx or NH3 (kg N/kg N) (see Table 4-17);

N(T)

=

number of animals per Type of animal in country;

Nex=

total nitrogen excretion by animals in country (kg N/yr);

Nex(T)=

nitrogen excretion per Type of animal in country (kg/yr)(see Table 4-6);

Nex(AWMS)=

nitrogen excretion per Animal Waste Management
System (kg/yr).

Worksheet 4-5A (Supplemental) MANURE NITROGEN USED AS FERTILISER
Use Worksheet 4-5A (Supplemental) to calculate Manure Nitrogen Used as
fertiliser, corrected for NH3 and NOx emissions and excluding manure
produced during grazing.
1 Enter the Total Nitrogen Excretion, Nex for all AWMS from column A,
sheet 3 Worksheet 4-1, into column A.
2 Enter the Fraction of Nitrogen burned for Fuel, FracFUEL, in column B.
See Table 4-17 for default data.
3 Enter the Fraction of Nitrogen Excreted during Grazing, FracGRAZ, incolumn C. See Table 1 in Appendix A, Pasture Range and Paddock.
4 Enter the Fraction of Nitrogen Excreted Emitted as NOx and NH3,
FracGASM, in column D. See Table 4-17 for default data. Note that thedata in Appendix A are in per cent. Divide these values by 100 to obtainthe Fraction of Nitrogen Excreted during Grazing.
5 Sum columns B, C and D and subtract the total from one. Enter thisfigure in column E.
6 Multiply columns A and E, and enter the result into column F to obtainthe Manure Nitrogen Used (corrected for NH3 and NOx emission andexcluding manure produced during grazing), FAW, into column F.
7 Enter FAW in Worksheet 4-5, sheet 1 in column A.

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TABLE 4-17
SUMMARY OF DEFAULT VALUES FOR PARAMETERS
FracBURN=

0.25 in developing countries 0.10 or less in developed countries (kg N/kg crop-N)

FracFUEL=

0.0 kg N/kg nitrogen excreted a

FracGASF=

0.1 kg NH3–N + NOx–N/kg of synthetic fertiliser nitrogen applied

FracGASM=

0.2 kg NH3–N + NOx–N/kg of nitrogen excreted by livestock

FracGRAZ=

See Table A-1, Appendix A (Column Pasture Range and Paddock).a

FracLEACH=

0.3 kg N/kg nitrogen of fertiliser or manure

FracNCRBF=

0.03 kg N/kg of dry biomass

FracNCR0=

0.015 kg N/kg of dry biomass

FracR

=

0.45 kg N/kg crop-N

a Countries are recommended to obtain country specific data.

3. Calculation of total nitrogen input in N-fixing crops (FBN)
Nitrogen input from N-fixing crops (FBN, kg N/yr) can be calculated from dry
biomass production of pulses and soybean in country, CropBF (kg/yr;):
EQUATION 5
FBN = 2 x CropBF x FracNCRBF
where:
CropBF=

production of pulses(kg dry biomass/yr);+soybeansincountry

FracNCRBF=

fraction of nitrogen in N-fixing crop (kg N/kg of dry
biomass) (see Table 4-17). The factor 2 converts the
FAO crop production to total crop biomass.

Enter FBN in Worksheet 4-5, sheet 1 in column A.

4. Calculation of nitrogen input from crop residues (FCR)
Data needed to calculate nitrogen input from crop residues (FCR) are:• Dry biomass production of pulses and soybean in country, CropBF (kg/yr)• Dry biomass production of other crops in country, Crop0 (kg/yr)
These numbers can be obtained from FAO databases.

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Crop residue returned to soils (FCR, in kg N/yr) is calculated as:
EQUATION 6
FCR = 2 x [Crop0 x FracNCR0 + CropBF x FracNCRBF] x (1-FracR)
x (1-FracBURN)
where:
CropBF=

production of pulses(kg dry biomass/yr);+soybeansincountry

Crop0=

production of non-N-fixing(kg dry biomass/yr);

crops

in

country

FracNCRBF=

fractionofnitrogeninN-fixing(kg N/kg of dry biomass) (see Table 4-17);

crops

FracNCR0=

fractionofnitrogeninnon-N-fixing(kg N/kg of dry biomass) (see Table 4-17);

crops

FracR

=

fraction of crop residue that is removed from the field
as crop (kg N/kg crop-N) (see Table 4-17);

FracBURN=

fraction of crop residue that is burned rather than left
on field (see Table 4-17).

The factor 2 converts edible crop production to total crop biomass
production.
Worksheet 4-5B (Supplemental) NITROGEN INPUT FROM CROP RESIDUES
Use Worksheet 4-5B (Supplemental) to calculate Nitrogen input from Crop
Residues.
1 Enter the Production of non-N-fixing crops, Crop0, in a country intocolumn A. If production data are not available as dry biomass, multiply
Crop0 by (1-0.15) to account for crop water content.
2 Enter the Fraction of Nitrogen of non-N-fixing crops, FracNCR0, intocolumn B. See Table 4-17 for default values.
3 Enter the Production of Pulses and Soybeans, CropBFN, into column C. If
production data are not available as dry biomass, multiply Crop0 by (10.15) to account for crop water content.
4 Enter the Fraction of Nitrogen in N-fixing crops, FracNCRBF intocolumn D. See Table 4-17 for default data.
5 Subtract the Fraction of Crop Residue Removed from Field, FracR, fromone, and enter the result in column F. See Table 4-17 for default data.
6 Subtract the Fraction of Crop Residue Burnt, FracBURN, from one, andenter the result in column G. See Table 4-17 for default data.

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7 Multiply columns A and B, and columns C with D. Sum the products, andmultiply the result with the values in columns F and G. Multiply the result
by 2 and enter the result into column H to obtain the nitrogen input
from crop residues, FCR.
8 Enter FCR in Worksheet 4-5, sheet 1 in column A.

STEP 2 ESTIMATING DIRECT NITROUS
OXIDE EMISSIONS EXCLUDINGCULTIVATION OF HISTOSOLS
1 Enter Emission Factors for Direct Emissions in column B. Use default
values for emission factor EF1 provided in Table 4-18 or more precise
locally available data.
2 Multiply the Amount of N input (column A) by the Emission Factor for
Direct Emissions (column B) to give the Direct Soil emissions of N2O.
Multiply the final result by 10-6 to express it as gigagrams. Enter the
results in column C.
3 Sum the Direct Soil Emissions and enter the total in the bottom of thecolumn C.

STEP 3 ESTIMATING DIRECT N2O
EMISSIONS FROM CULTIVATION OF
HISTOSOLS
1 Enter Area of Cultivated Organic Soils, Fos , in column D.
2 Enter Emission Factor for Direct Soil Emissions in column E. Use default
values for Emission Factor, EF2 provided in Table 4-18 or more precise
locally available data.
3 Multiply the Area of Cultivated Organic Soils (column D) by Emission
Factor for Direct Soil Emissions (column E) to give the total Direct
Emissions from Histosols. Multiply the final result by 10-6 to express it
as gigagrams. Enter the result in column F.
TABLE 4-18
SUMMARY OF DEFAULT EMISSION FACTORSFOR AGRICULTURAL EMISSIONS OF N2O
EF1=

0.0125 (0.0025-0.0225) kg N2O–N/kg nitrogen input

EF2=

5 temperate and 10 tropical (2-15) (kg N/ha/yr)

EF3=

see Table 4-8

EF4=0.01 (0.002-0.02) kg N2O–N per kg NH3–N and NOx–N emitted

EF5=0.025 (0.002-0.12) kg N2O–N per kg nitrogen leaching/runoff

EF6=

0.01 (0.002-0.12) kg N2O–N per kg sewage-N produced

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STEP 4 ESTIMATING TOTAL DIRECT N2O
EMISSIONS
Direct N2O emissions can be calculated from the following equation:
EQUATION 7
N2ODIRECT (kg N/yr) = [FSN + FAW + FCR + FBN] x EF1 + FOS x EF2
1 Add the two totals from columns C and F together and then multiply by
the conversion ratio 44/28 to give the Total Direct N2O Emissions.
Enter the result in column G.

STEP 5 ESTIMATING SOIL EMISSIONS OF
N2O FROM GRAZING ANIMALS
Only emissions from pasture range and paddock are reported here. The
N2O emissions from other Waste Management Systems are reported under
Manure Management (Worksheet 4-1, sheet 2). N2O emissions fromgrazing animals (N2OANIMALS in kg N/yr) can be calculated as follows:
EQUATION 8
N2OANIMALS = N2O(AWMS)=∑ (T)[ N(T) x Nex(T) x AWMS(T) x EF3(AWMS)]
where:

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N2OANIMALS=N2O emissions from animal production in acountry (kg N/yr);

N2O(AWMS)=

N2O emissions from Animal Waste Management
Systems in the country (kg N/yr);=[N(T=1) x Nex(T=1) x AWMS(T=1) x EF3(AWMS)]+ ...
+ [N(T=TMAX) x Nex(T=TMAX) x AWMS(T=TMAX) x
EF3(AWMS)] ;

N(T)

=

number of animals of type T in the country;

Nex(T)=

N excretion of animals of type T in the country(kg N/animal /yr); (see Table 4-6);

AWMS(T)=

fraction of Nex(T) that is managed in one of thedifferent distinguished animal waste management
systems for animals of type T in the country; (seeTable 4-7);

EF3(AWMS)=

N2O emission factor for an AWMS (kgN2O-N/kg of Nex in AWMS); (see Table 4-8);

T=

type of animal category;

TMAX

=

maximum types of animals distinguished in the
country.

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1 Enter Nitrogen Excretion, Nex(AWMS), value for Pasture Range andPaddock (from Worksheet 4-1 Supplemental) into column A.
2 Enter Emission Factor for AWMS in column B. Use default values for
Emission Factors, EF3, provided in Table 4-18 or more precise locallyavailable data.
3 Multiply Nex(AWMS) (column A) by the Emission Factor (column B) andthen by the conversion ratio 44/28 to give Emissions of Nitrous Oxide
from Grazing Animals. Multiply the final result by 10-6 to express it asgigagrams. Enter the result in column C.

STEP 6 ESTIMATING INDIRECT EMISSIONSFROM ATMOSPHERIC DEPOSITION OF NH3
AND NOX
1 Enter the total amount of Synthetic Fertiliser N Applied to Soil, N(FERT), incolumn A.
2 Enter the Fraction of Synthetic Fertiliser N Applied that Volatilizes (FracGASFS) in column B. Use default values provided in Table 4-17 or more
precise locally available data.
3 Multiply the total Amount of Synthetic Fertiliser Applied in the country(column A) by the Fraction of Synthetic Fertiliser N Applied that
Volatilizes (column B) to give the total Amount of Synthetic Fertiliser
Applied to Soil that Volatilizes. Enter the result in column C.
4 Enter the Total N Excretion by Livestock (Nex) calculated using
equation 3 in column D.
5 Enter the Fraction of Total Manure N Excreted that Volatilizes(FracGASM) in column E. Use default values provided in Table 4-17 ormore precise locally available data.
6 Multiply the Total N Excretion by Livestock, (Nex), (column D) by
Fraction of Total Manure N Excreted that Volatilizes, FracGASM, (column
E). Enter the result in column F.
7 Enter Emission Factor, EF4, in column G. Use default values provided inTable 4-18 or more precise locally available data.
8 Add columns C and F and then multiply by Emission Factor, EF4,
(column G) to give Nitrous Oxide Emissions. Multiply the final result by
10-6 to express it as gigagrams. Enter the result in column H.

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STEP 7 ESTIMATING INDIRECT EMISSIONSFROM LEACHING
1 Enter the total amount of Synthetic Fertiliser Use in the country N(FERT)in column I.
2 Enter the total Livestock N Excretion (Nex), calculated using Equation 3,
in column J.
3 Enter the Fraction of N that Leaches, Frac LEACH, in column K. Use
default values provided in Table 4-17 or more precise locally available
data.
4 Enter the Emission Factor, EF5, in column L. Use default values provided
in Table 4-18 or more precise locally available data.
5 Add total amount of Synthetic Fertiliser Use in the country N(FERT)(column I) to Nex (column J). Multiply by Frac LEACH (column K) andthen by EF5 (column L) to give the indirect Nitrous Oxide Emissions
from Leaching. Multiply the final result by 10-6 to express it as gigagram.
Enter the result in column M.

STEP 8ESTIMATING INDIRECT EMISSIONS

Indirect N2O emissions (kg/yr) can now be calculated in Worksheet 4-5,
Sheets 1 (atmospheric deposition), and 2 (leaching and runoff) as:
EQUATION 9
N2OINDIRECT = N2O(G) + N2O(L)where:
N2O(G)=(NFERT x FracGASF + Nex FracGASM) x EF4;

N2O(L)=(NFERT + Nex) x FracLEACH x EF5.

where:
FracLEACH=

fraction of nitrogen input to soils that is lost
through leaching and runoff (kg N/kg of nitrogen
applied); (see Table 4-19);

N2OINDIRECT=

indirect N2O emissions from country (kg N/yr);

N2O(G)=

N2O emissions from country due to atmosphericdeposition of NH3 and NOx (kg N/yr);

N2O(L)=

N2O emissions from country due to nitrogenleaching and runoff (kg N/yr).

1 Sum the two totals in columns H and M and then multiply by theconversion ratio 44/28 to give the Total Indirect Nitrous Oxide
Emissions. Enter the result in column N.

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