# Disaggregated N O emission factors associated with deposition of sheep excreta in temperate grasslands

Aude Mancia, David Chadwick, Simon Waters, Dominika J Krol

► To cite this version:

Aude Mancia, David Chadwick, Simon Waters, Dominika J Krol. Disaggregated N O emission factors associated with deposition of sheep excreta in temperate grasslands. Livestock and Climate Change: What's next?, Dec 2019, Londres, United Kingdom. http://hal-05381492

HAL Id: hal-05381492

https://hal.inrae.fr/hal-05381492v1

Submitted on 25 Nov 2025

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Distributed under a Creative Commons Attribution 4.0 International License
# Disaggregated N₂O emission factors associated with deposition of sheep excreta in temperate grasslands

A.Mancia<fnref n="1" />, D.Chadwick<fnref n="2" />, S.Waters<fnref n="3" />, D.Krol<fnref n="1" />

aude.mancia@teagasc.ie

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Teagasc
AGRICULTURE AND FOOD DEVELOPMENT AUTHORITY

<figure><img src="image_3.png" /></figure>

PRIFYSGOL BANGOR UNIVERSITY

## 1. Introduction

* Contribution of grazing ruminants to global warming through the deposition of urine and faeces onto soils.

* Excreta patches → large nitrogen (N) inputs → stimulation of nitrifiers/denitrifiers → increased N cycling rate → increased risk of N₂O emissions.

* Default values for N₂O emissions from ruminants excreta deposition → IPCC Tier 1 emission factors (EFs).

* Great spatial and temporal variations → need to develop country-specific (Tier 2) EFs.

## 2. Objective

* To generate data to contribute to new EFs for N₂O emissions associated with sheep excreta deposition in grasslands, by disaggregating emissions by type of excreta and season of application.

* To assess climatic and soil factors influencing these emissions through the study of three seasons of deposition.

## 3. Methodology

Fully randomized block design trial in Athenry, Ireland (Fig. 1 a)

Parameters: N₂O and mineral N.

Treatments:

* control (C),

* sheep urine (U),

* artificial urine (AU),

* sheep dung (D),

* sheep urine + nitrification inhibitor (U+ NI), for autumn application only.

Collection of excreta from local ewes for each season (Fig. 1 b).

Treatments applied by hand. N₂O and mineral N measured for 365 days after each application.

<figure><img src="image_4.png" /><figcaption>Fig 1. Excreta collection (a) and experimental site with static chambers for N₂O sampling (b).</figcaption></figure>

## 4. Results

* Significant effect (p<0.05) of treatments on cumulative N₂O emissions calculated one month (spring) and one week (summer) after application

* Disaggregated (partial) EF estimated for the 1st month after spring application = **0.04 %** (assuming excreted N = 60% urinary N and 40% faecal N)

<figure><img src="image_5.png" /></figure>

<figure><img src="image_6.png" /><figcaption>Fig 2. Mean cumulative N₂O emissions (a) and mean daily N₂O fluxes (b) for the first month of spring application. Means followed by same letter are not significantly different at P< 0.05 according to the Tukey statistical test.</figcaption></figure>

## 5. Discussion and Conclusions

* Importance to refine IPCC Tier 1 EF which appears to be overestimated (Tier 1 EF = 1% for sheep excreta deposition)

* Importance to disaggregate emissions from urine and dung

* Similar experiment will be reproduced in a different sheep grazing system in Connemara, in 2020 (rough-grazed pasture on peat soil)

<footnote n="1">¹Teagasc, Crops, Environment and Land Use, Johnstown Castle, Co. Wexford, Ireland</footnote>

<footnote n="2">²The School of Natural Science, Bangor University, Bangor, UK</footnote>

<footnote n="3">³Teagasc, Animal and Grassland Research and Innovation Centre, Grange, Dunsany, Co. Meath</footnote>