Jarrod Miller, Jamie Taraila, and Amy Shober
Farmers must make several decisions when considering termination of cover crops. Early termination is typically the easiest option, since it reduces issues related to planting into a standing cover crop. In 2018, planting green decreased corn stands by 10,000 plants per acre in our Sussex County research plots. This type of stand reduction when planting green is not expected for all soil or cover crop combinations.
Certainly, having good soil moisture and some luck can help to increase plant populations when planting green, but the biggest factor affecting stand establishment is seed placement and depth. As such, it is important to get out and check seed placement and depth when planting green, making any adjustments to the planter as necessary. For example, we found that simply raising our row cleaners provided us with better planting conditions when planting green into our research plots in Georgetown.
With support from USDA-NRCS, we are evaluating the effects of four cover crop single species or mixes (None, Rye, Rye/Vetch, and Rye/Clover) as well as two termination timings on soil nitrogen (N) in sandy and finer textured soils. We currently have one year of data from this study. We found no difference in corn yield when planted into crops with or without any cover crop when planted into sandy, irrigated soils. However, we found thatlater termination of cover crops decreased corn yield by 16 bushels. In contrast, corn yields were 12 to 15 bushels greater when corn was planted following any of the cover crop species/mixtures. For soybeans, later cover crop termination had no effect on yields, although there was evidence that soybean yields were increased when planting into plots with cover crops. The study will be repeated for the next two years, which will help us determine if these results were significant. However, it appears that cover crop termination timing is more flexible prior to planting soybean, so farmers can choose the option that provides the most flexibility Yet, it is important to note that cover crops are not a one size fits all solution, and their benefits and drawbacks will vary annually and by soil type.
