LAND APPLICATION OF BEEF FEEDYARD EFFLUENT TO FARAGE SORGHUM AND WINTER WHEAT

摘要

CAFO's feed approximately seven million head of cattle annually in the Texas High Plains. Regulations require that all runoff from precipitation be contained and disposed to land. Feedlot runoff was applied to 27 plots of winter wheat and forage sorghum over 24 months at the USDA Conservation and Production Research Laboratory located at Bushland, Texas. Winter wheat and forage sorghum were planted and grown for hay. Runoff was applied by flood irrigation onto level borders. Rates applied were as follows: 0 cm/cropping season (TRT 1, control), 25 cm (TRT 2) and 50 cm (TRT 3). Cropping rotations of sorghum-fallow (SF), wheat-fallow (WF) and sorghum-wheat (SW) (two crops/year) were used for each TRT. Plots were irrigated every two weeks after plant emergence until the appropriate amount of effluent was obtained. Above ground biomass samples were collected and allowed to air dry for three weeks, after which they were ground mixed and sent to the laboratory for analysis. Soil samples were collected before planting and after harvest and analyzed at the laboratory. Effluent samples were collected three times during each irrigation, composited, and analyzed. TRT 3 SW had the greatest total yield (28, 564 kg/ha) followed by WF (19,153 kg/ha) and SF (14,337 kg/ha). Residual soil nutrient concentrations were more dependent on initial nutrient concentrations than on effluent application or cropping rotations. Residual soil N was 70% dependent on initial N, while residual soil P was 56% dependent on initialP.