|KRUEGER, ERIK - University Of Minnesota|
|OSCHNER, TYSON - Oklahoma State University|
|PORTER, PAUL - University Of Minnesota|
Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/31/2010
Publication Date: 3/1/2011
Citation: Krueger, E., Oschner, T., Porter, P., Baker, J.M. 2011. Winter rye cover crop management influences on soil water, soil nitrate, and corn development. Agronomy Journal. 103(2):316-323.
Interpretive Summary: Winter rye has been advocated as a cover crop for corn and soybean systems to provide soil protection and to scavenge excess nitrate frol the soil. However, farmers have concerns about its effect on the subsequent grain crop, particularly with respect to soil water depletion and immobilization of nitrogen. We conducted an experiment to determine the impacts of winter rye on soil moisture, soil nitrogen, and subsequent corn growth, and to see whether those impacts might differ if the rye were harvested rather than killed and left in the field. The study was conducted for 2 years, 2008 and 2009, in Morris, MN. Silage corn was planted after either winter fallow, a rye crop terminated 3 to 4 weeks earlier, or a rye crop harvested 2 days before planting. Soil moisture was not different between the fallow treatment and the killed treatment, but was 16% lower in the harvested rye treatment. Soil nitrate levels were lower in both of the rye treatments relative to the fallow treatment, with a 35% reduction in the killed treatment and a 59% reduction in the harvested treatment. Subsequent corn yield was similar in the fallow and killed treatments but lower by 4.5 Mg ha-1 in the harvested rye treatment.Total forage yield (rye +corn) was similar in all treatments. We conclude that winter rye can be used as a double crop without impacting corn yield if it is killed early, but later termination to allow forage harvest will likely result in reduced corn production.
Technical Abstract: A winter rye (Secale cereale L.) cover crop can be seeded after corn (Zea mays L.) silage to mitigate some of the environmental concerns associated with this cropping system. Rye can be managed as a cover crop by chemical termination or harvested as for forage. A field study was conducted in Morris, MN in 2008 and 2009 to determine the impact of killed and harvested rye cover crop on soil moisture and NO3-N and to monitor the impact of the rye on subsequent corn yield. Corn for silage was seeded either after winter fallow, after a rye cover crop terminated three to four weeks before corn planting, or after a rye forage crop harvested no more than two days before corn planting. Soil moisture after the killed rye cover crop was similar to winter fallow but was decreased 16% after harvested rye. Available soil NO3-N was decreased after both killed rye (35%) and harvested rye (59%) compared to winter fallow. Corn yield after killed rye was similar to corn after winter fallow, but yield was reduced 4.5 Mg ha-1 after harvested rye. Total forage yield was similar for all treatments. This work demonstrates that the environmental benefits of a winter rye cover crop may be achieved without impacting corn yield, but the later termination required for rye forage production may result in soil resource depletion and may negatively impact corn silage yield.