Forage management impacts I: Soil phosphorus fractions and P export in runoff

Authors: Franklin, Dorcas; BUTLER, D - UGA; CABRERA, M - UGA; Steiner, Jean; RISSE, L - UGA; GASKIN, J - UGA

Submitted to: Soil and Water Conservation Society
Publication Type: Abstract Only
Publication Acceptance Date: 7/21/2007
Publication Date: 7/21/2007
Citation: Franklin, D.H., Butler, D.M., Cabrera, M.L., Steiner, J.L., Risse, L.M., Gaskin, J.W. 2007. Forage management impacts I: Soil phosphorus fractions and P export in runoff [abstract]. Soil and Water Conservation Society 2007 Annual Meeting, July 22-25, 2007, Tampa, Fl. CD-ROM.

Interpretive Summary:

Technical Abstract: A greater understanding of the role of forage management impacts on soil P fractions and P export in runoff at the field-scale can enhance agricultural sustainability and water quality. Eighteen farm fields, with forages managed as pasture or hay systems were outfitted with small in-field runoff collectors (SIRCs) and runoff, soil test P (STP), and soil water soluble P (WSP) were monitored from 1999 to 2006. Nutrient treatment of fields was either rich in P (broiler litter or dairy slurry) or without P amendments (inorganic N or unfertilized). Even as STP levels affected export of dissolved reactive P (DRP) and total P in runoff (P < 0.05), export of P was most affected by management system and the application of P in manures. Mean concentrations of DRP were greater under pasture management (3.52 mg P L-1) than hay management (2.07 mg P L-1) for all nutrient treatments, despite lower STP levels under pasture management (150 mg P kg-1 vs. 218 mg P kg-1). In addition to runoff P concentrations, levels of runoff P mass export will also be examined. The on-farm, field-scale data from this study may be most useful for adjusting and improving models of agricultural P export used by farmers and professionals to conserve nutrients and protect environmental quality.