Soil and Water Losses as Affected by Tillage and Manure Application

Little data are available on conservation tillage under field conditions characteristic of a dairy operation. Thus, simulated rainfall was used to compare soil and water losses among conventional, chisel, and no‐till systems for corn both with and without surface‐applied manure prior to tillage. Rainfall was applied at several times during the growing season of 1978 and 1979. A portion of the previous year's crop residue was removed in 1978 and all the residue was left in 1979. A tillage × date interaction was observed for runoff losses in both years of the experiment. Significantly lower runoff occurred for the conventional and chisel systems relative to the no‐till system immediately after planting. At later sampling periods, runoff significantly increased for the conventional system and runoff losses approached that from no‐till. In contrast, lower runoff losses occurred for the chisel system relative to the other tillage systems. This was most apparent in 1979 when more residue was partially incorporated or left on the soil surface. Surface spread manure decreased runoff for all tillage treatments at the September 1978 sampling period and at both sampling periods in 1979. The results indicated the greatest response with the chisel system. In 1978 and 1979, a tillage × manure interaction was observed for soil loss. In 1978, little difference in soil loss was observed among unmanured tillage treatments. However, the application of manure reduced soil losses for chisel and no‐till systems relative to the conventional system. In 1979, soil losses were lower from unmanured chisel and unmanured no‐till treatments than from the unmanured conventional treatment. Soil losses were significantly lower from the manured chisel treatment than all other treatments.