Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 12, 2010
Publication Date: N/A
Interpretive Summary: Manure incorporation into soils may reduce odors and ammonia emissions and improve air quality; but these practices may also increase nitrate leaching and reduce ground water quality. This 4-year field trial discovered significant tradeoffs in the amount and pathway of manure nitrogen (N) loss. Compared to non-incorporated manure, partially incorporated manure and injected manure reduced ammonia loss by 47 and 74%, respectively. Partially incorporated manure had the greatest nitrate leaching loss. Although incorporation methods impacted manure N loss, methods did not impact crop yield, crop N uptake or soil properties at trial’s end. These results demonstrated inevitable losses of manure N and the tradeoffs when managing manure to improve air quality vs. water quality. This information is important to livestock producers, consultants, and policy makers wanting to improve manure management.
Technical Abstract: To reduce odors and conserve dairy slurry nitrogen (N) for subsequent crop use, various slurry application techniques have been tested. Reductions in ammonia (NH3) emissions through slurry incorporation or other soil management techniques may, however, increase nitrate (NO3) leaching. Possible tradeoffs in slurry N loss as NH3 or NO3 were evaluated over 4 yrs in south central Wisconsin. Dairy slurry was applied each spring at a single rate (approx 75 ML ha-1) in either of 3 ways: surface broadcast (SURF), surface broadcast followed by partial incorporation using an aerator implement (AER-INC) and injection (INJ). Ammonia emissions were measured during the 120 h following slurry application using the equilibrium concentration technique and NO3 leaching was monitored in drainage lysimeters. Yields and N uptake of oats (Avena sativa), corn (Zea mays L.) and winter rye (Secale cereale L.) were measured each year, and at trial’s end soils were sampled in 15-30cm increments to 90cm depth. There were significant tradeoffs in the amount of pathway of slurry N loss: NH3-N emissions were 5.6, 38.3, 12.4 and 21.8 kg ha-1 and NO3¬-N leaching was 26.6, 0.9, 16.9 and 7.3 kg ha-1 during years 1, 2, 3, and 4, respectively. Compared to SURF, AER-INC and INJ reduced NH3 loss by 47 and 74%, respectively. AER-INC had the greatest NO3 loss however, a pattern that continued during the years after trial’s end. Although slurry incorporation impacted patterns of N loss and cumulative N loss, they did not impact crop yield, crop N uptake or soil properties at trial’s end.