Monday, November 13, 2006
48-2

Phosphorus Dynamics in Soil, Runoff, and Sediment From Three Management Systems.

Michael Cox1, William Kingery1, Patrick Gerard1, Geoffrey Brink2, and Keith McGregor3. (1) Mississippi State Univ, Box 9555, Mississippi State, MS 39762, (2) US Dairy Forage Research Center, 1925 Linden Dr West, Madison, WI 53706-1108, (3) National Sedimentation Laboratory, P.O. Box 1157, Oxford, MS 38655

While continued land application of poultry litter is inevitable, producers are being encouraged to use previously unamended fields. However, little information is available as to P dynamics in soil, runoff, and sediment from these unamended fields. The objectives of this study were to: 1) to determine phosphorus buildup in soils with poultry litter additions under three management systems on two soil series; 2) evaluate soluble and sediment P losses under three common management systems; and 3) to evaluate the forms of phosphorus in sediment and runoff. Three management systems combining tillage and planting date treatments used on two soil series were evaluated with respect to runoff and sediment losses, soil P buildup, and P levels and forms in runoff and sediment. Phosphorus mass balance for each management system was also determined. Losses of sediment and runoff from the soils were not significantly different due to the high variability of the runoff data, however, System 2 did have higher sediment losses in both soils. Sediment P was not significantly different between the management systems within each soil. Soluble P losses in runoff were the major P loss mechanism for both soils with inorganic P dominating this fraction. Total soil P increased significantly in both soil series, however there was no difference between the management systems within soil series. These results suggest that soluble P must be controlled to adverse environmental impacts.


Handout (.pdf format, 70.0 kb)