To meet conservation compliance requirements, a standard of at least 30% residue cover must remain on the soil surface after planting. The type of manure application equipment used can significantly affect the amount of residue cover remaining on soil surface. In this study, residue cover was estimated after the application of liquid manure at four different rates with three different types of manure applicators.
The type of application equipment also had a significant impact on the amount of residue remaining after manure application. Disc-covered manure applicators were more aggressive in overturning soil and residue to cover the applied manure. The shovel incorporator had more visible disturbance due to the shovel mixing of the applied manure with the soil. On the other hand, the slot injector was less disruptive to surface residue because it applies the manure below the soil surface. The rate of manure application had a relatively smaller impact on corn and soybean surface residue cover. However, the rate of manure application can impact residue cover depending on the types of both the manure applicator and crop residue.
Effective manure application and residue management can be combined to improve both soil productivity and environmental quality. The slot injector applicator disturbed the minimum amount of soybean surface residue while applying manure at high rates. Under corn residue, the disc-covered manure applicator left more than 30% residue cover, therefore meeting conservation compliance requirements.