The purpose of this research was to identify trade-offs among soil erosion, soil health, and crop production when using cover crops with manure application.Continuous corn silage cropping systems in Wisconsin leads to overall removal of N from the system unless manure is applied. However, this cropping system allows for the planting of cover crops or a winter silage crop post harvest, which may lead to increases in soil N over time. Cover crops are valuable in these corn-silage based rotations as they also provide ground cover after harvest and can reduce N leaching after fall manure application.
The cropping system investigated was a continuous corn silage system with fall manure application. The experiment was a randomized complete block split-plot design where the whole plot treatments were no cover, rye as a cover (chemically terminated) or as a forage (harvested) crop and the split plot treatment was depth.The objective of this study was to determine the effect of cover cropping on potentially mineralizable nitrogen (PMN) over a growing season using a 7-day anaerobic incubation (2015 and 2016 season), a long-term aerobic incubation (2015 season), and N uptake by corn.
There were no statistical differences in short-term PMN among cover crop treatments at any time point in 2015 or 2016. However, the cover crop treatments led to a yield reduction compared to no cover crop use in both years. Thus, our study showed significant effects of cover cropping on agronomic factors like corn yield and N uptake but these same differences were not measurable in the soil N.
This work will continue to evaluate the long-term effects of cover crop use on soil health.
Matthew Ruark, University of Wisconsin-Madison
Jaimie West, Kavya Khrishnan, Kevin Shelley