Dairy Slurry Application Method Effects On NH3 Emission, and NO3 Leaching in No-till Corn Silage.

Most losses of ammonia N from dairy farms occurs during periods of manure land application. To reduce odors and conserve manure N for subsequent crop use, various manure application techniques have been tested. Reduction in ammonia N loss due to manure injection or other soil management techniques may increase however manure N losses via nitrate leaching. Possible tradeoff in manure N losses via ammonia volatilization and nitrate leaching were evaluated over a 4 y period in south central Wisconsin. Dairy slurry was applied each spring at a single rate (approx 30 ML ha^-1) in either of 3 ways: shallow injection (INJ), surface broadcast followed by partial incorporation using an AerWay implement (AER) and surface application without incorporation (SUR). Ammonia was captured during the 120 h following manure application using dynamic chambers placed on treated soil surfaces above drainage lysimeters. Corn yield and N uptake was measured each year and soils were sampled at trial’s end. Ammonia emission rates were highest during the period just after manure application, most of the losses occurring within 24-48 hours. Losses were greatest from SUR, but were reduced by 30 to 70% by INJ and AER (SUR > AER > INJ in 3 of 4 yrs). The quantity of ammonia N lost, and in some cases relative treatment effects, varied greatly depending on soil and weather conditions, and manure characteristics during each application period. Our presentation will include partitioning of total manure N applied each year into relative amounts of N volatilized as ammonia, leached as nitrate, taken up by corn, and remaining in soil at trial’s end.