Nutrient and bacterial transport in runoff from soil and pond ash amended feedlot surfaces

The addition of pond ash (fly ash that has been placed in evaporative ponds and subsequently dewatered) to feedlot surfaces provides a healthier environment for livestock and economic advantages for the feedlot operator. However, the water quality effects of pond ash amended surfaces are not well understood. The objectives of this field investigation were to: (1) compare feedlot soil properties, and nutrient and bacterial transport in runoff, from pond ash amended surfaces and soil surfaces; (2) compare the effects of unconsolidated surface materials (USM) (loose manure pack) and consolidated subsurface materials (CSM) (compacted manure and underlying layers) on nutrient and bacterial transport in runoff; and (3) determine if the measured water quality parameters are correlated to soil properties. Simulated rainfall events were applied to 0.75 m wide × 2 m long plots with different surface materials and surface conditions. Measurements of calcium, magnesium, sulfur, and pH were found to be significantly greater on the pond ash amended surfaces. In comparison, the soil surfaces contained significantly greater amounts of Bray 1-P. The runoff load of NH ₄-N was significantly greater on the pond ash amended surfaces, while the total phosphorus (TP) load was significantly greater on the soil surfaces. The NO ₃-N and total nitrogen (TN) loads in runoff were significantly greater on the feedlot surfaces containing CSM. Concentrations of E. coli in runoff were similar on the pond ash amended surfaces and soil surfaces. The dissolved phosphorus (DP), particulate phosphorus (PP), and TP load of runoff were all significantly correlated to Bray 1-P measurements.