Transport of Arsenic and Phosphorus in Ditch Flow From Litter-Amended Soils and Barn Areas.

Little is known about the fate of arsenic (As) in land applied litter from chickens that have been fed roxarsone, an organic feed additive containing As. This study seeks to elucidate the transfer of As in runoff from ditch drained soils of the poultry producing region of the Delmarva Peninsula by tracking As and phosphorus (P) export from seven drainage ditches over two water years (July 1, 2005 to June 30, 2007). Annual losses of As from ditches ranged from 0.003 to 0.140 kg ha^-1 while P losses ranged from 0.43 to 16.55 kg ha^-1, with the largest loads associated with a litter storage shed that served as a point source. Event-based As and P losses in ditch flow fluctuated by a factor of 162 and 1882, respectively. The two elements were correlated in flow from the ditch draining the litter storage shed (r =0.68), pointing to similar behavior under point source conditions. Indeed, As and P exhibited similar behavior within storms for all ditches, characterized by relatively high initial concentrations subject to rapid concentration declines prior to peak flow, consistent with dilution of a finite source. However, there was significant concentration differences between ditches and considerable temporal variability within ditches, with no clear seasonal trends or associations with current management strategies. Both similarities and dissimilarities in As and P behavior in ditch flow help to inform the sustainable management of poultry litter.