Trace Element Losses in Runoff Due to Subsurface - Applied Poultry Litter On a Coastal Plain Soil.

Delmarva’s four poultry companies and 1,800 growers generated roughly 9 million tons of poultry litter in 2008. This litter is primarily used to inexpensively fertilize farmland to support staple crop production (e.g., corn, soybeans and wheat). This trend over long periods (20-30 yrs) could cause a build-up of certain trace elements (e.g., arsenic, selenium, mercury, and zinc) in some soils, which can contaminate water resources at relatively low levels. Additionally, the widespread adoption of no-till farming on Delmarva, and the usual practice of surface (broadcast) application of poultry litter have led to elevated trace element transport in surface runoff to nearby water bodies. Three poultry litter amendment treatments – broadcast (conventional no-till), subsurface application and broadcast/disked were compared with an unamended control (no litter) on the poorly drained Othello series to the well drained Matapeake series. Immediately after litter application, five intact soil lysimeters (61 x 61 x 61 cm) were collected from each treatment area. Lysimeters were set at 3% slope and subjected to rainfall simulation (1 hr, 6.06 cm/hr) 15 and 43 days after litter application. Runoff samples were analyzed for dissolved and particulate trace elements as mentioned earlier. Results showed that a first-generation USDA subsurface applicator developed by USDA-ARS located at Auburn University, has the potential to lower runoff movement of trace elements of concern by about 2-fold as compared to broadcast application. This was accomplished by placing dry poultry litter below the depth of interaction between runoff water and the A-horizon of the soil profile, thus dissolved manure components moved less via surface runoff. This study supports the recommendation of the adoption of litter subsurface application technology on Delmarva no-till soils. It is anticipated that this technology will have widespread appeal beyond the borders of Delmarva, especially in other high poultry producing states such as Arkansas.