Manure Incorporation and Crop Residue Cover — Part I

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, increased availability of nutrients, and control of potential manure runoff; however, disturbing the soil and crop residue may increase soil erosion and water runoff. This NebGuide summarizes the results of a field study to determine the influences on crop residue cover of common equipment used to simultaneously apply and incorporate manure.

Maintaining crop residue on the soil surface is one of the most cost-effective soil erosion control practices. Compared to a cleanly tilled field, erosion can be reduced by 50 percent when just 20 percent of the soil surface is covered with residue. A best management practice for soil erosion control is to minimize soil and crop residue disturbance, thus leaving more crop residue on the soil surface. Today's livestock producer must balance these two best management practices.

Three general configurations of soil-engaging components are typically used with tank spreaders and towed hose systems to simultaneously apply and incorporate either liquid or slurry manure: chisels and sweeps, disk-type applicators, and coulter-type applicators.Residue cover reduction averaged 92 percent when chisel and sweep injectors were used in soybean and oat residue. In some instances, residue was reduced by as much as 98 percent. In corn residue, the average reduction was 52 percent with chisel and sweep injectors, with reductions ranging from 25 to 87 percent. Average residue cover reductions with the tandem disk were about the same as those from the chisel and sweep injectors in all four residues.

Average residue cover reduction by the disk-type applicator was 72 percent for soybean and oat residues and 45 percent for corn residue. Residue cover reduction by the disk applicators was not significantly different compared with the tandem disk in either irrigated or non-irrigated corn residue, but was significantly less in soybean and oat residues.

Residue cover reductions by the coulter-type applicator were significantly less than the reductions caused by all other components. When taken across year and season, mean residue cover reduction for the coulter applicator was 37 percent for soybean and oat residues and 11 percent for corn residue.