Project Number: 6612-11120-003-01
Project Type: Reimbursable

Start Date: Oct 01, 2003
End Date: Sep 14, 2007

Objective:
Evaluate the effects of extracting time, extracting ratio, and extraction pH on water-soluble P and bioavailable P in broiler litter, layer manure, and dairy manure. Characterize water-soluble P and particulate P forms in broiler litter, layer, and dairy manures. Compare laboratory measurements of water-soluble P and bioavailable P with water-soluble P and bioavailable P in field runoff. Study the dynamics of manure P in soil. Evaluate the effect of mechanical treatments on volume and quality of surface runoff from grasslands fertilized with animal manures.

Approach:
Rainfall will be applied to small-undisturbed grassed soil blocks receiving surface applications of broiler litter, layer manure, and dairy manure. Runoff water will be collected and analyzed for total P, inorganic P, organic P. Adsorption isotherms for P will be developed for soils with zero, ten and twenty years of manure applications. Different mechanical (M) treatments will be applied to 2 m2 grass plots and simulated rainfall will be used to measure the volume and quality of surface runoff. One M treatment will be compared to no M treatments on 0.8 ha grass plots fertilized with broiler litter. Runoff volume and P species in runoff will be measured.