Underseeding cover crops to maximize biomass and ground cover. 2009 Research and Demonstration Report
Seeding or underseeding the cover crop in a standing crop may be a strategy to allow for enough time for sufficient biomass accumulation to minimize erosion and N losses. Seven field demonstration plots and two research trials were establish in seed and sweet corn to evaluate the impact of underseeding alfalfa on corn yield and cover crop biomass production. Based on first year results, there was no difference in sweet corn yields between treatments with or without undersown cover crops. Cover crops did not establish well under sweet corn and did not provide enough cover by harvest to minimize erosion or contribute to an N credit for the following crop. Cover crop growth was greater in seed corn than sweet corn. This was likely due to the open canopy in seed corn allowing light to get through to the cover crop. Based on the demonstration and research trials in one year, there appears to be little risk that undersown alfalfa will reduce sweet or seed corn yield. None of the undersown cover crops impacted seed corn 1000 kernel weight or test weight compared to the no cover crop control. Results from the research trial indicate higher cover crop biomass at seed corn harvest with oilseed radish and the mixture of cover crops (oilseed radish, vetch, oats and alfalfa) compared to alfalfa. There was no difference in corn yield, 1000 kernel weight or test weight between early July or early August sowing of cover crops but July sown cover crops put on more biomass growth than the later planting. However both planting dates provided enough time for good growth. Late fall and spring cover crop biomass samples will be collected at select sites as well as the N credit from alfalfa in 2010. Ground cover assessments (a rough estimate of potential to minimize soil erosion) will be initiated in November. Matching funding is in place to continue this project in 2010.