Simulated management effects on ammonia emissions from field applied manure

A need exists to improve the utilization of manure nutrients by minimizing NH3 emissions from land application of manure. Management strategies to reduce NH3 emissions are available; however, few have been validated under Canadian conditions. A well tested and accurate simulation model, however, can help overcome this challenge by determining appropriate management strategies for a given set of field conditions.The Volt'Air simulation model was utilized to estimate NH3 volatilization from manure spreading for various manure spreading considerations under a range of atmospheric conditions typically encountered in eastern Canada. Considerations included: (i) soil liming, (ii) time of day of manure spreading, (iii) rainfall (timing and amount) and (iv) manure incorporation (timing, depth and manure coverage).Results demonstrated that liming to increase soil pH, increased NH3 emissions by 3.3 kg ha−1 for each increment of 0.1 pH (up to a 1.5 total increase), over no liming at 34.6 kg ha−1. For each hour delay in manure spreading past 0800 h, NH3 losses were reduced by 1.5 kg ha−1. Rainfall (10 mm) at least 20 h after manure application reduced losses, with increased reductions at higher rainfall amounts. Incorporation soon (1 h) after application was best for NH3 mitigation. Increasing the depth of incorporation by 5 cm reduced NH3 emissions by 4.4 kg ha−1; also increasing manure coverage by incorporation reduced losses by 2 kg ha−1 for each 10% increase in coverage, compared to surface application at 34.6 kg ha−1. This investigation using Volt'Air yielded valuable information about simulating manure management strategies and the magnitude of their effects on NH3 emissions.