Integrating Management Into the Georgia P-Index.

Management of farming operations in the Southern Piedmont can have a significant impact on phosphorus (P) losses in runoff from grasslands and from croplands regardless of soil test P.  The impact of grassland management on P losses in runoff was determined for nine farm fields, managed as pasture or hay systems.  Fields were outfitted with a total of 28 runoff collectors.  Runoff P, soil P, and management practices were monitored from 2004 to 2007.  Four of the hay fields were converted to improved hay systems and overseeded (improved) and two pastures were overseeded in the winter.  Nutrient treatment of fields varied from those rich in P (broiler litter or dairy slurry) to those without P amendments (inorganic nitrogen (N) or no amendments).  Data relating to nutrient applications, soil P, field topography, and forage management were used as input values to determine the grassland management most effective in reducing P export in runoff.  Results indicated that measured P export in runoff was lowest from hayfields and improved hayfields.  Pastures with no manure or amendments applied had the highest P losses in runoff.