The Arkansas poultry industry produced more than 1.2 billion broiler chickens (Gallus gallus domesticus) and generated approximately 1.3 million Mg of broiler litter in 2002. High transportation costs of relocating broiler litter have led to annual land applications near poultry houses, increasing concern for potential surface water contamination from runoff. The objective of this study was to evaluate the effect of broiler litter application rate on runoff water quality in response to natural precipitation. Six plots (1.5 by 6.0 m), located on a Captina silt loam (finesilty, siliceous, active, mesic Typic Fragiudult), were amended with fresh broiler litter at 0, 5.6, and 11.2 Mg ha(-1) (control, low, and high litter treatments, respectively) once annually for 4 yr (May 2003 through April 2007). Runoff collected after each runoff-producing event was analyzed for soluble nutrients and metals. Cumulative runoff did not differ among litter treatments over the 4-yr study. At times, flow-weighted mean (FWM) concentrations of As from all litter treatments exceeded the maximum contaminant level for drinking water (0.01 mg As L(-1)). Four-year FWM Fe concentrations and runoff losses were greater (P < 0.05) from the high than from the low litter treatment and unamended control, and the 4-yr FWM P concentration from the low litter treatment (3.0 mg L(-1)) was greater than that from the unamended control (1.8 mg L(-1)). Since precipitation is temporally variable, evaluating runoff water quality in response to natural precipitation over several years is key to ascertaining the long-term impacts of surface-applied soil amendments like broiler litter.

Repeated annual land application of organic soil amendments, such as broiler litter (BL), to managed grasslands for increased forage yields has increased concerns about potential surface water contamination from runoff. Furthermore, water quality concerns are exacerbated in areas of underlying karst, such as the Ozark Highlands, where runoff can rapidly enter the groundwater system. Therefore, the objective of this study was to determine 8‐yr (May 2003–April 2011) linear trends in annual runoff water quality from a silt loam soil in the Ozark Highlands region of northwest Arkansas under natural precipitation and typical forage management amended annually with BL at three application rates (0 [control], 5.6 [low], and 11.2 [high] Mg BL ha−1) with a history of BL amendments and high soil‐test P. Average annual runoff, flow‐weighted mean (FWM) runoff concentrations of Ca, Cd, Cu, Na, and Se, and all nutrient and metal losses increased with time (P < 0.05) but were unaffected (P > 0.05) by BL application rate. Average annual FWM concentrations of As decreased with time (P < 0.05) and were unaffected by BL (P > 0.05). Eight‐year cumulative runoff losses of Se exceeded 200% of that applied in BL. Results indicated that pasturelands with a history of BL application and high soil‐test P may continue to release BL‐derived As and Se at concentrations potentially harmful to human and environmental health regardless of current management practice long after litter application has ceased.

Broiler litter is often applied to pastures as an organic fertilizer. A history of repeated annual litter application can increase soil‐test P concentrations to levels that can result in degraded water quality if P‐enriched sediment enters waterways after being transported from areas prone to erosion. Nutrient management tools, such as the P Index, are being used in many areas of concentrated broiler production as a means to limit the amount of P added to soil in litter applications. However, it is unclear how soon forage producers may need to begin using inorganic fertilizers to supply nutrients to meet target yields if P‐based nutrient management plans indicate that litter application should cease. The main objective of this study was to evaluate annual dry matter (DM) yield trends for broiler litter application rates of 0, 2.5, and 5 tons/acre over a 6‐year period for a site that had high near‐surface, soil‐test P and enriched soil organic matter from a history of litter application. Results demonstrate that DM yields were maintain at an average of 2.7 tons/acre for 6 years following the cessation of litter application without decline. We conclude that the use of costly inorganic fertilizers can be delayed for several years because the release of N via decomposition of litter‐enriched soil organic matter is likely adequate to maintain modest DM yields.