Highlights Emissions from land-applied manure could be mitigated with prior biochar treatment. A 6.5 mm thick layer of biochar applied prior to manure pumpout was effective. NH3 and H2S emissions were reduced by ~90% and 61%, respectively, in the first 24 h. Subsequent land application of treated manure results in a 0.1 m3 ha-1 biochar spread. Abstract. Air quality management is essential for sustainable livestock production. Manure generates odorous and greenhouse gas emissions during storage and cropland application. Ammonia (NH 3 ) emissions during manure application to soil represent a loss of nitrogen and decrease the value of manure. Biochar (BC) can mitigate emissions during manure storage. In this research, we hypothesized that BC-treated manure generates less emissions after post-storage application to cropland soil. This study tested the effect of BC thickness (dose) and manure treatment timing on gaseous emissions with controlled lab-scale experiments. Both NH 3 and hydrogen sulfide (H 2 S) emissions from cropland soil amended with BC-treated manure were reduced. Overall, average percent reductions in the first 6 h / 24 h was 89.9% / 89.7% and 59.6% / 60.8% for NH 3 and H 2 S emissions, respectively, when manure was treated with BC immediately prior to application to the soil. When manure was treated with BC during storage, emissions of NH 3 and H 2 S were reduced 20.7% / 21.8% and 12.2% / 13.5%, respectively. The percent reductions in NH 3 and H 2 S for 13- and 6.5-mm BC application thicknesses were not significantly different, but the 2.5-mm application thickness treatment was less effective at reducing gas emissions. The effects of BC application on methane), carbon dioxide, and odor were inconclusive. Observational data indicated a possible mitigation trend in odor, especially for the BC treatment added immediately prior to application to soil, but further trials are needed. Scaling up the technoeconomic analysis showed that less than 6 m 3 of BC would be needed to treat more than 900 m 2 surface of stored manure in a typical 1,200-head swine barn with a uniform 6.5 mm thick BC layer. Subsequent cropland application of such BC-treated manure would result in 0.1 m 3 ha -1 BC addition to soil in a typical corn-soybean crop rotation system. This research shows that BC has the potential to mitigate gaseous emissions while promoting nutrient cycling and the sustainability of livestock waste as a fertilizer. Keywords: Air quality, Environmental technology, Greenhouse gases, Livestock production, Nutrient management, Odor control, Sustainable agriculture, Waste management.
O’Brien et al. (Thu,) studied this question.