Tuesday, November 14, 2006
206-4
Manure Source and Rate Effects on Soil Test Levels and Corn Growth.
Emily G. Sneller and Carrie Laboski. Dept of Soil Science, Univ of Wisconsin, 1525 Observatory Dr, Madison, WI 53706
Phosphorus (P) has become an increasing environmental concern with regard to surface water quality and has caused nutrient management recommendations in Wisconsin to focus more closely on P. This study was conducted to determine manure P availability to corn on a total P applied basis, as compared to fertilizer in a field setting. Dairy slurry, solid dairy manure, swine slurry, poultry pellets, and P fertilizer were applied at three target rates of 90, 180, and 270 kg total P2O5 ha-1 at Arlington and Marshfield, WI. Bray P-1 and water extractable P were measured at 2, 4, and 10 weeks after application. For the 2005 growing season, change in soil test P levels varied. At Marshfield, all treatments increased soil test P levels above the no P control. In addition, fertilizer increased soil test P levels more than dairy slurry, solid dairy manure, and swine slurry. At Arlington, all treatments increased soil test P levels above the control, with dairy slurry and poultry pellets increasing soil test P levels similarly to fertilizer. Both solid dairy manure and swine slurry increased soil test P through the 90 kg total P2O5 ha-1 target rate and then plateaued as total P applied increased. Tissue samples were collected at the V5, R1, and R6 growth stages along with grain samples at the R6 stage and analyzed for P concentration. Silage yield was determined at the R6 stage. Maximum silage yield at both locations was achieved at the 180 kg total P2O5 ha-1 target rate after which yield plateaued as total P applied increased. The manure sources increased soil test P levels less than or equal to fertilizer on a total P applied basis. First year manure P availability coefficients should vary based on manure source.