Wednesday, November 15, 2006

Adaptive Management in Grasslands to Improve Water Quality.

Dorcas Franklin1, Miguel Cabrera2, J.L. Steiner1, and Mark Risse2. (1) USDA-ARS, 1420 Experiment Station Rd, Watkinsville, GA 30677, (2) Univ of Georgia, Plnt Sci Bldg-1201 Mason Mill Rd, Athens, GA 30602

Grassland management practices may influence nutrient concentrations in streams, both base flow and storm flow, when nutrients are applied at recommended rates. Scientists, producers and educators examined the extent to which nutrients (phosphorus (P) and nitrogen (N)) were present (from 1999 to 2004) in both soluble and particulate forms for grasslands (hay and pasture) downstream of stream-side fields fertilized with broiler litter. Ratios of dissolved to total P were 0.68 in base flow and 0.62 in storm flow for hay fields and 0.57 in base flow and 0.48 in storm flow for pastures . Differences between management systems were more obvious with ratios of N than of P. Ratios of dissolved N (NH4+ & NO3) to total Kjeldahl N were 0.69 in base flow and 0.52 in storm flow for hay fields, and 0.82 in base flow and 0.45 in storm flow for pastures. As part of a participatory research project, group recommendations for whole farm management practices were to modify positions of hay fields. New hay field positions are on the lower side of each stream-side field with pastures on the upper side of each hay field.