Nutrient transport in runoff from feedlots as affected by wet distiller's grain diet

Distiller's byproducts can serve as valuable sources of protein and energy for beef cattle. When the characteristics of materials entering and exiting the plant are compared, the nutrients in distiller's byproducts are concentrated about three times. The objectives of this study were to: a) measure soil properties and nutrient transport in runoff from feedlot surfaces as affected by corn-based and wet distillers grain diets, b) compare the effects of unconsolidated surface materials (USM) (loose manure pack) and consolidated subsurface materials (CSM) (compacted manure and underlying layers) on soil characteristics and nutrient transport, c) determine if runoff nutrient transport from corn-based or wet distillers grain diets is correlated to selected feedlot soil properties, and d) identify the effects of varying runoff rate on nutrient transport. Simulated rainfall events were applied to 0.75-m wide by 2-m long plots. Measurements of calcium, copper, loss on ignition, magnesium, organic-N, potassium, sulfur, total N (TN), and zinc were significantly greater within the pens where cattle were fed a cornbased diet. The pens where distiller's grains were fed contained significantly greater amounts of Bray 1-P. Surface condition (USM or CSM) did not significantly affect any of the feedlot properties except potassium content. Use of a wet distillers grain diet did not significantly affect any of the measured runoff water quality parameters. Runoff measurements of NH₄-N, TN, NO ₃N, total dissolved solids, and EC were each significantly correlated to six or more feedlot parameters. Each of the measured water quality parameters was significantly influenced by runoff rate.