Evaluation of ammonia, nitrous oxide and odour emissions from surface applied liquid and solid swine manure

Surface applied swine manure has the potential to promote greenhouse gases such as nitrous oxide (N2O), ammonia (NH 3) volatilization and odour emissions. This research involved conducting field trials at Agriculture and Agri-Food Canada (AAFC) Harrington Research Farm in Prince Edward Island (PE) to assess simultaneous emissions from surface applied swine manure. Manure was applied to grain stubble fields on sandy loam soils. The effect of manure type (liquid and solid), application rates and rainfall events before and after manure spreading were examined. The influence of meteorological conditions on gaseous losses was also evaluated. Ammonia emissions were measured using a simple micrometeorological technique, wind tunnels, and/or closed chambers.;This research has found that NH3 emissions are the primary concern under these soil conditions when dealing with N losses. This identified a need to narrow the focus to more easily evaluate the effect of management strategies on NH3 loss under a wide range of atmospheric conditions. The NH3 volatilization model, Volt'Air was validated from regional data. The model provided good overall agreement (R2=0.91) with observed and field measured results for >5 d periods. The model was used to investigate various management scenarios and found NH3 emissions can be reduced when applying late in the day, applying 20 h prior to a rainfall and also when incorporating soon after application, at greater soil depths and with higher manure coverage rates.;Results show a limited dependence with regards to odour emissions and manure type, application rate and rainfall before and after spreading, due to high variability and challenges with using current olfactometry methods. The use of liquid manure reduced NH3 emissions by 32% compared to solid manure. Increasing application rates enhanced NH3 emissions. Applying manure prior to rainfall reduced NH3 losses by 36%. Ammonia and odour emissions were similar in their dependence on atmospheric conditions with greater emissions at increased air and soil temperature, net radiation, vapour pressure deficit and windspeed. Nitrous oxide emissions were low in magnitude and dependence, suggesting that management strategies to reduce both odour and NH3 were not enhancing N2O emissions when applied to the soils utilized for this research.