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item Johnson, Timothy
item Kaspar, Thomas - Tom
item Kohler, Keith

Submitted to: Leopold Center for Sustainable Agriculture Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 7/31/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Cover crops can reduce erosion following soybean, but they have rarely been used in the upper Midwest because of the cold and short growing season following soybean harvest. One way to overcome this problem is to overseed an oat cover crop into soybeans before harvest. Oats grow well in cool weather, the seed is inexpensive, and will germinate and survive under a soybean canopy. The possibility exists, however, that an oat cover cop could reduce yields of both the soybean and the following corn crops. A study was conducted from 1991 to 1996 to examine the effect of an oat cover crop on corn and soybean yields. Overseeding oats into soybean reduced soybean yield in only one of six years and had no effect on corn yield. We also wanted to develop a method of predicting the potential for oat cover crop growth at a given location. Producers need some estimate of cover crop growth to determine whether it is worth trying at their location. We surmised that growing degree days, precipitation, and soybean yield were factors that affected the amount of cover crop growth in the fall. Using these three factors we were able to get good agreement between predicted and actual values for the data from 1991 to 1995. The data from 1996, however, did not follow this relationship, and we suspect that in 1996 not enough oat plants were established to respond to the favorable weather later in the fall. We hope to use this relationship to prepare maps of Iowa and the upper Midwest showing potential oat cover crop growth.