|CAVADINI, JASON - University Of Wisconsin|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 8/25/2015
Publication Date: 11/13/2015
Citation: Jokela, W.E., Sherman, J.F., Cavadini, J. 2015. Nutrient runoff losses from liquid dairy manure applied with low-disturbance methods. Meeting Abstract. ASA-CSSA-SSSA, Madison, WI.
Technical Abstract: Manure applied to cropland is a source of P and N in surface runoff and can contribute to impairment of surface waters. Immediate tillage incorporates manure into the soil, which may reduce nutrient loss in runoff, as well as N loss via NH3 volatilization. But tillage also incorporates crop residue, which may increase erosion potential. We applied liquid dairy manure in a silage corn-rye cover crop system in late October using methods designed to incorporate manure with minimal soil and residue disturbance. These include strip-till injection (low-disturbance sweep injection ridged with paired disks) and tine aerator-band manure application, which applies bands of manure over aerator slots to encourage manure infiltration. These were compared to standard broadcast application, either incorporated with a disk or left on the surface. Runoff was generated with a portable rainfall simulator (40 mm/h for 30 min) 3 separate times: a) 2 to 5 days after manure application, b) early spring, and c) after tillage and planting. Runoff was collected from 2 x 2 m subplots bordered by a steel frame with a PVC gutter at the lower end to collect runoff. In the post-manure runoff the highest losses of total and dissolved P were from surface-applied manure, as would be expected. Total P loss was reduced by approximately 35% by the aerator band method, 70% by disk incorporation, and almost 90% by strip-till injection, which was not statistically different from the no-manure control. Dissolved P losses followed a similar pattern, but with even greater reductions from injected or incorporated manure. In the two spring runoff events P losses were much lower and there were fewer significant differences. Overall, results show that the low-disturbance manure application methods can greatly reduce nutrient runoff losses compared to surface application, while maintaining residue cover better than disk incorporation of manure.