Covering reduces emissions of ammonia, methane, and nitrous oxide from stockpiled broiler litter

Poultry litter, a mix of excreta, bedding material, and discarded feed, is extracted from poultry houses, and used as fertiliser. The litter is often stored in stockpiles outside before field application thereby posing a risk for negative environmental and climatic impact from emissions of ammonia (NH 3 ) and greenhouse gases (GHG). This study investigated the emissions of methane (CH 4 ), NH 3 , and nitrous oxide (N 2 O) from a 22 tonnes broiler litter stockpile over 44 days. The emissions were measured on a farm-scale stockpile with and without coverage using the backward Lagrangian Stochastic method. The results showed distinct emission patterns for each gas during the measurement periods. For all compounds, the emissions during the covered period were significantly lower than during the two uncovered periods. The reduction due to coverage was 92–95% for NH 3 , 25–40% for CH 4 , and 82–89% for N 2 O. NH 3 emissions were highest immediately after coverage removal and during stockpile removal. CH 4 emissions were highest during stockpile removal and lowest during coverage. N 2 O emissions were lowest during coverage but a notable increase after coverage removal was observed. The temperature within the stockpile showed variations at different heights, with the highest temperatures recorded in the middle of the stockpile. GHG emissions, based on global warming potential, indicate substantial contributions from N 2 O, accounting for 55–72% of emissions in CO 2 -equivalents during uncovered periods and 27% during coverage. Furthermore, GHG emissions were reduced 63–72% during coverage compared to the uncovered periods highlighting the importance for immediate coverage of stockpiles to minimise NH 3 and GHG emissions. Science4Impact Statement The findings of this study offer clear, actionable insights for poultry farm operators and environmental regulators seeking to reduce harmful emissions from broiler litter stockpiles. This reduction not only limits the environmental impact but also minimizes nutrient losses. For farm operators, implementing immediate and continuous coverage of stockpiles can be an efficient, cost-effective strategy to comply with environmental regulations and reduce greenhouse gas emissions. For policymakers, these results provide a basis to recommend or enforce stockpile covering as a best practice for mitigating agricultural emissions, contributing to climate action and improved air quality. • Backward Lagrangian Stochastic method used for emissions from broiler litter. • Farm-scale stockpile investigated with and without cover for 42 days. • NH 3 , N 2 O, and CH 4 emissions were significantly lower during covered period. • Timely coverage of stockpiles is effective for mitigation of NH 3 and GHG emissions.