Pathways of N Loss Following Manure Application: Water and Air Quality Trade Offs.

Prudent management of manure resources on agricultural lands is critical to protecting air and water quality. Over the past few years there has been considerable interest in promoting technologies that incorporate manures into soils without significant tillage. Surface application leaves manure vulnerable to environmental processes that enrich surface runoff with dissolved nutrients and increase emissions of ammonia and odor to the atmosphere. Understanding the agronomic and environmental trade-offs of different manure application technologies is important to their sustainable use. In this study, we established twelve field-scale lysimeters (15 meters by 27 meters) on the Kepler Research Farm near Rock Springs, PA. Six lysimeters were treated with a conventional surface application of dairy manure (rate = 62.7tonnes/ha), whereas the other six lysimeters received subsurface application of manure using the shallow disk injection technology. After manure was applied to the lysimeters, we monitored nitrate in surface and subsurface runoff on an event basis. In addition, ammonia gas measurements were taken immediately after application for 24-48 hours using a photoacoustic gas analyzer. In this presentation, we contrast acute losses of nitrogen through ammonia volatilization with seasonal losses of nitrate to surface and subsurface runoff over the course of the 2011/2012 sampling campaign. Highlighting these two aspects of the study demonstrates potential trade-offs associated with the conventional and new subsurface manure application technologies.