Crop residue cover and manure incorporation. I. Reduction of percent cover

Manure incorporation represents a compromise between best management practices for soil erosion control and manure management. Manure should be incorporated into the soil for odor control, maximum availability of nutrients, and control of potential manure runoff. However, disturbance of the soil and crop residue should be minimized for soil erosion control. This field study was conducted to: 1) determine the influence that commercially available soil-engaging components used to simultaneously apply and incorporate manure have on the reduction of crop residue cover Part I - this article; and 2) determine and evaluate some of the factors that may influence the amount of residue cover reduction that occurs with these components Part II - companion article. Seven different configurations of manure injectors/applicators were operated in residue from irrigated corn (Zea mays L.), non-irrigated corn, corn that had been harvested as silage, soybeans (Glycine max L. Merr.), and oats (Avena sativa L.) in the fall and/or spring of three different crop years. Averaged across crop, year, and season, residue cover reduction was significantly less for coulter-type applicators than for disk-type applicators (P < 0.001), disk-type applicators reduced residue cover significantly less than chisel and sweep injectors (P < 0.001), and chisel and sweep injectors reduced residue cover similar to a tandem disk (P = 0.398). Suggested ranges of values to estimate the reduction of corn (non-fragile) residue cover are: chisel and sweep injectors, 35% to 70%; disk-type applicators, 35% to 60%; and coulter-type applicators, 5% to 20%. Similarly, for soybean or oat (fragile) residue, suggested estimates of residue cover reduction are: chisel and sweep injectors, 85% to 95%; disk-type applicators, 60% to 85%; and coulter-type applicators, 20% to 35%. These values can be used for planning purposes when site-specific data are not available. Results of this research indicate that certain configurations of manure application equipment may leave adequate residue cover for acceptable soil erosion control, particularly in non-fragile residue. However, the equipment must be selected, adjusted, and operated with the dual objectives of residue and manure management, rather than used simply as a means of manure disposal.