A climate-dependent global model of ammonia emissions from chicken farming

• Published in: Biogeosciences Vol. 18; no. 1; pp. 135 - 158
• Main Authors: Jiang, Jize, Stevenson, David S, Uwizeye, Aimable, Tempio, Giuseppe, Sutton, Mark A
• Format: Journal Article
• Language: English
• Published: Katlenburg-Lindau Copernicus GmbH 08-01-2021; Copernicus Publications
• Subjects: Acidification; Aerosols; Agricultural ecosystems; Agricultural industry; Agricultural practices; Agriculture; Air quality; Air quality management; Ammonia; Ammonia emissions; Analysis; Aquatic ecosystems; Atmosphere; Chickens; Climate; Climate change; Climate effects; Climate models; Cold climates; Emission inventories; Emissions; Environmental aspects; Environmental changes; Environmental impact; Eutrophication; Excretion; Farming; Farms; Farmyard manure; Global temperature changes; Houses; Housing; Livestock; Livestock farms; Manures; Meteorology; Nitrogen; Poultry; Poultry farming; Poultry industry; Resolution; Simulation; Temporal variations; Terrestrial environments; Tropical climate; Tropical environments; Uric acid; Weather; Wet climates
• ISSN: 1726-4189; 1726-4170; 1726-4189
• DOI: 10.5194/bg-18-135-2021

Ammonia (NH3) has significant impacts on the environment, which can
influence climate and air quality and cause acidification and
eutrophication in terrestrial and aquatic ecosystems. Agricultural
activities are the main sources of NH3 emissions globally. Emissions of NH3 from chicken farming are highly dependent on climate, affecting
their environmental footprint and impact. In order to investigate the
effects of meteorological factors and to quantify how climate change affects these emissions, a process-based model, AMmonia–CLIMate–Poultry
(AMCLIM–Poultry), has been developed to simulate and predict temporal
variations in NH3 emissions from poultry excretion, here focusing on
chicken farms and manure spreading. The model simulates the decomposition of uric acid to form total ammoniacal nitrogen, which then partitions into
gaseous NH3 that is released to the atmosphere at an hourly to daily
resolution. Ammonia emissions are simulated by calculating nitrogen and
moisture budgets within poultry excretion, including a dependence on
environmental variables. By applying the model with global data for
livestock, agricultural practice and meteorology, we calculate NH3
emissions from chicken farming on a global scale (0.5∘ resolution).
Based on 2010 data, the AMCLIM–Poultry model estimates NH3 emissions
from global chicken farming of 5.5 ± 1.2 Tg N yr−1, about 13 % of the agriculture-derived NH3 emissions. Taking account of partial control of the ambient environment for housed chicken (layers and broilers), the fraction of excreted nitrogen emitted as NH3 is found to be up to 3 times larger in humid tropical locations than in cold or dry
locations. For spreading of manure to land, rain becomes a critical driver
affecting emissions in addition to temperature, with the emission fraction
being up to 5 times larger in the semi-dry tropics than in cold, wet
climates. The results highlight the importance of incorporating climate
effects into global NH3 emissions inventories for agricultural sources. The model shows increased emissions under warm and wet conditions,
indicating that climate change will tend to increase NH3 emissions over the coming century.