Volatilization of ammonia from manure as affected by manure additives, temperature and mixing

Ammonia (NH3) volatilization decreases the N-nutrient value of livestock manure slurries and can lead to soil acidification and eutrophication problems. In this study the effect of three manure additives (Euro Mest-mix® (Mx), Effective Micro-organisms® (EM), and Agri-mest® (Am)) on NH3 volatilization at three temperatures (4, 20, and 35 °C) was investigated. The manufacturers claim that Mx contains absorbing clay minerals and that applying Am and EM to slurry will reduce nitrogen losses, most likely by enhancing the biodegradation of manure slurry. Furthermore, the effect of mixing slurry on NH3 volatilization has been investigated. Ammonia volatilization increased with increasing temperature and mixing of the slurries. However, at 35 °C mixing of manure reduced NH3 emissions compared to non-mixing, which is related to a reduced crust resistance to gaseous transport at higher temperatures for non-mixing. Moreover, mixing introduces oxygen into the anaerobic slurry environment which will slow down microbial activity. The use of additives did not change manure characteristics (pH, dry matter, Ntotal, Nmineral, C/N, and C/Norganic) and did not result in a significant (p < 0.05) decrease in NH3 emissions, except that at 4 °C and no mixing a significant decrease of 34% in NH3 volatilization was observed, when Am and EM together, were applied to slurry.