Characterization of Solids and Nutrient Retention of a Manure Storage Tank in a Dairy Manure Handling System

摘要

Management strategies that concentrate manure nutrients reduce transportation and handling costs. The objective of this project was to characterize the retention of solids and nutrients in a manure tank on a 200-cow dairy. The above-ground manure storage tank evaluated in this project was 5.73 m high by 31.5 m in diameter and held 4,480 m3. Effluent from a screen separator was pumped directly into the manure tank, and manure left the tank through a gravity overflow pipe located approximately 0.5 m from the top of the tank. Samples of manure were collected from four separate locations at depths of 0.3 m and 2.7 m and composited for analysis. Profile manure samples were collected to a depth of 4.3 m from each of the four locations and analyzed individually. Samples were collected during cleanout to determine the effectiveness Of the tank agitation. Solids in the tank profile increased from 0.8% to 3.3%. During the first cleanout, the nutrient content of the slurry was 0.86, 0.13, and 0.32 g/L of total N, P, and K, respectively. Total N, P, and K concentrations were 1.2,0.19, and 0.38 g/L, respectively, during the second cleanout. Using estimates of nutrient concentrations in the manure to calculate nutrient retention, approximately 18%, 17%, and 26%of the estimated annual N, P, and K excretion from the dairy cows, respectively, was retained in the manure tank. The increase in nutrients and solids in the manure profile indicated the manure tank did concentrate nutrients in this dairy manure system.