Assessing Tillage Systems for Reducing Ammonia Volatilization From Spring-Applied Slurry Manure.

Application of slurry manure can provide essential plant nutrients for crop production, but loss of NH3-N from manure to the environment decreases its value as a fertilizer. The effect of tillage systems on reducing NH₃-N volatilization and their influence on succeeding corn (Zea mays L.) silage production were studied at the University of Massachusetts Research Farm during 2010–2012 growing seasons. Tillage treatments consisted of disking before and after manure application, solid-tine aeration before and after manure application, and no-till management. Ammonia emissions were monitored for 100 h after slurry manure was applied to the fields using closed chambers with acid traps. Regardless of tillage treatments, the greatest NH₃-N loss (61%) occurred within the first 8 h after slurry manure application. The greatest NH₃-N emission occurred with surface application (no-till) which ranged between 5.2-10.3 kg NH₃-N ha^-1 over the three years of the study. Immediate incorporation of manure into soil through disking reduced NH₃-N loss by 66 to 75%. Ammonia loss abatement with aeration before or after manure application ranged from 13 to 41% compared with surface manure application. Soil nitrate (NO₃-N) concentration overall was not significantly different between the no-till and disking systems. However, there was more NO₃-N available in the soil in August, a time when the corn could still benefit from additional N, when manure had been disked into soil compared with no-till treatment. Tillage systems did not influence corn silage yield and quality.