Manure application technology and the impact on nitrogen dynamics
The loss of nitrogen from liquid hog manure is an environmental and economical concern. This study examined the influence of application method (aerator, deep injection, shallow injection, surface applied non incorporated and surface applied incorporated at different timings after application) and timing of application (summer, fall, and spring) on ammonia emissions, nitrogen leaching, and plant uptake of nitrogen. The aeration and incorporation treatments had significantly greater ammonia emissions than injection treatments. When the manure was incorporated immediately, it generally led to significantly lower emissions than when incorporated at 1, 3, or 5 days after application. Also, emissions from injection treatments are not significantly different than the untreated, and had significantly less ammonia loss than the other application methods. There were no significant yield differences between treatments, which was attributed to the low demand for additional nitrogen during the 2005 growing season. However, there was a general trend across sample dates of greater soil mineral N, and plant nitrogen uptake for injection treatments, and manure application times closer to the growing season. Based on these results, it appears that application timing, and method can beneficially affect nitrogen uptake and loss when manure is injected, and applied closer to the growing season.