Submitted to: ASAE Annual International Meeting
Publication Type: Proceedings
Publication Acceptance Date: 8/1/2003
Publication Date: 8/1/2003
Citation: GRANDE, J., KARTHIKEYAN, K.G., PANUSKA, J., POWELL, J.M. CROPPING SYSTEM EFFECT ON SOLUBLE AND SEDIMENT-BOUND PHOSPHORUS LOSSES. ASAE ANNUAL INTERNATIONAL MEETING. 2003. Interpretive Summary:
Technical Abstract: Land area devoted to corn silage is increasing on Wisconsin dairy farms. The height of silage harvest may influence residue cover of soils and therefore runoff losses and water quality. We examined cropping system effects on sediment and phosphorus (P) losses from no-till fields planted to corn. Treatments included conventional corn grain (CG) and silage (CS-L) and non-conventional, high-cut (24-26") silage (CS-H). Each treatment also received one of three manure treatments: no manure, manure application in fall or manure application in spring. Simulated rainfall (76 mm/hr; 1 h) was applied in the spring and fall, runoff from 2.0 m x 1.5 m plots collected and a sub-sample analyzed for total sediments, dissolved reactive phosphorus (DRP), and total phosphorus (TP). Compared to CS-L, CS-H was effective in reducing sediment and P losses. The reductions were greatest in fall runoff and were enhanced by manure addition. Runoff depth, sediment load, DRP load, and TP load were reduced by 50% when no manure was added and by 85% with manure applied in either season. Although sediment, DRP, and TP concentrations were higher under manure application, the secondary effect of enhanced infiltration resulted in lower values on a load basis. Reductions were smaller following spring rainfall. DRP concentration was sensitive to manure application timing while TP concentration was not. Compared to the no manure treatment, DRP concentrations in runoff from all crop residue treatments were five times greater following spring manure application, while TP concentrations were highest under no manure. Preliminary data on particle size distribution in transported sediments reveal an increased concentration of fines (< 2mm) on manure-applied plots. Recently applied spring manure protected the soil the most, but leads to the preferential selection of finer particles.