Effects of broiler litter management practices on phosphorus, copper, zinc, manganese, and arsenic concentrations in Maryland Coastal Plain soils

The objective of this research was to assess the long-term effects of broiler litter applications on soil phosphorus (P), copper (Cu), zinc (Zn), manganese (Mn), and arsenic (As) concentrations in Chesapeake Bay watershed Coastal Plain soils. Litter and soil samples were collected from 10 farms with more than 40 years of broiler production and from wooded sites adjacent to fields and were analyzed for P and metal contents. Averaged over farms, total P and metal concentrations in the litter were 12.8 g kg(-1) P and 332, 350, 334, and 2.93 mg kg(-1) Cu, Zn, Mn, and As, respectively. Surface (0-15 cm) soil pH values were greater than (5.7-6.4) the 0- to 15-cm depth at wooded sites (3.5-4.3). Surface soil Bray 1 P values (149-796 mg kg(-1)) in amended fields were greater than wooded sites (4.4-17 mg kg(-1)). The IN nitric acid (HNO3)-extractable metal concentrations were higher in amended soils than in wooded areas and were 7.7-32, 5.7-26, 12.3-71, and 0.6-3.0 mg kg(-1) for Cu, Zn, Mn, and As, respectively, compared to 0.76-14, 4.6-22, 1.6-70, and 0.14-0.59 mg kg(-1) for the same metals, respectively, in wooded areas. Results from this study demonstrated that long-term broiler litter applications have altered the chemical properties of the Coastal Plain soils of the Maryland Eastern Shore. Metal concentrations were low in the surface layer of amended fields and typically decreased with depth. Phosphorus additions rather than metals are most likely to contribute to the degradation of the Chesapeake Bay watershed.