MITIGATING PHOSPHORUS MOVEMENT FROM AGRICULTURAL FIELDS

Agriculture is often cited as the primary factor for the high P loads polluting Lake Erie and Ohio’s watersheds, but the contributions of agriculture as a system, a combination of tillage, best management practice (BMP) and fertilizer source rather than an industry is unknown. This study supplied either commercial fertilizer or poultry litter to tilled or no-till production systems with their corresponding BMPs of incorporation and cover crops, respectively, to determine the P lost via surface runoff. At two locations in the Maumee Watershed of Lake Erie, simulated rainfall was used to generate runoff following implementation of the above systems. One site had been under no-till for at least 20 years and the other had not. At both sites, incorporation of the commercial fertilizer reduced dissolved P compared to the commercial fertilizer left on the soil surface. The surface application of commercial fertilizer in the no-till plots resulted in similar runoff P concentrations with or without a cover crop at both locations. The application of poultry litter was not significantly different than the control for both tillage systems at one location, but was at the other location. This may be attributed to a combination of site differences and the nutrient solubility differences. Some degree of incorporation will likely decreasing dissolved P loading associated with runoff from either fertilizer source especially commercial fertilizer.