Disposal of Beef-Feedlot Manure: Effects of Residual and Yearly Applications on Corn and Soil Chemical Properties
1975
Wallingford, G. W. | Murphy, L. S. | Powers, W. L. | Manges, H. L.
Land disposal of beef-feedlot manure was studied. Annually, beginning in the fall of 1969, feedlot waste was applied to a silty clay loam soil at rates that after 4 years ranged from 114 to 2,750 metric tons/ha of dry manure. Included were three single applications made in the fall of 1969 (residual) that ranged from 123 to 590 dry metric tons/ha. For 3 years, in the spring and fall, surface soil samples and soil cores were taken. Yields of furrow-irrigated corn (Zea mays L.) forage and plant contents of N, P, K, Ca, Mg, and Na were measured. Chemical composition of manure from a single feedlot varied greatly. Average composition (dry weight basis) of samples collected for 3 years was 20.5% H₂O, 0.92% N, 0.52% P, 1.14% K, 0.92% Ca, 0.41% Mg, and 0.26% Na. At all sampling dates electrical conductivities (EC) of extracts from saturated pastes of the surface soil samples from plots receiving yearly manure treatments were linearly related to cumulative tons of applied manure; EC values of more than 10 mmho/cm were recorded for the spring samplings. Both yearly and residual manure treatments caused Na and NO₃-N to move downward accumulating to depths of at least 1 m after 3 years; movement of K and P was restricted to 50 and 30 cm, respectively. Corn-forage yields were increased by improved soil fertility at the low and intermediate yearly rates, but depressed at the high rates, probably because of salt injury. After 4 years forage yields were still increased on plots that received residual treatments. Uptake of N and P was also depressed at high yearly rates and followed trends similar to those of yield. Yearly rates ranging from 29 to 68 dry metric tons ha⁻¹ year⁻¹ produced near maximum forage yields without causing excessive salt accumulation in the soil.
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