Quantitative Approach to Identify Phosphorus Hotspots and Predict Phosphorus Loss Risk in Poultry Litter Impacted Soils of Lake Wedowee Watershed in Alabama.

Poultry is the second-largest agricultural industry in Alabama with an economic impact of $15.1 billion in revenue. Poultry litter (PL) is bulky which limits their economical long distance transportation. Repeated land application of PL results in buildup of P in soil leading to creation of “P hotspots” near the poultry operations. This accumulated P in soil is susceptible to P loss via runoff and promote eutrophication of surface water. Lake Wedowee watershed in Alabama is of prime importance mainly due to expansion of poultry operations in the area. Tools such as P index or soil test P (STP) are used to indicate the potential for P loss risk to environment; however, the effectiveness of these tools to estimate P loss risk is not clear for Alabama soils. Additionally, no work has been done to understand the P retentive capacity of soils in Wedowee watershed. The objective of this study are to 1) estimate the soil P storage capacity (SPSC) of soils under different management practices in Lake Wedowee watershed; and b) quantify and compare the potential risk of P loss using the approaches of SPSC, P-Index, and STP. Soil samples to a depth of 60 cm were collected at multiple locations in the Wedowee watershed comprising of pasture lands, row crop, and hay operations. Water soluble phosphorus (WSP), Mehlich-1(M1), Mehlich-3 (M3) and Oxalate (Ox) extractions were performed on these soil samples using the standard procedures. Preliminary results on SPSC and comparisons between different tools to estimate risk of P loss will be presented.