Semester of Graduation
First Major Professor
Master of Science (MS)
An indispensable component of a healthy organic system is inclusion of cover crops. While a key element in maintenance and improvement of soil properties, reduction of weed pressure, and additions and recycling of nutrients, challenges of managing these crops between cash crops can add frustration and pose risk to the grower. A recent interest in tillage radish has organic farmers in the Midwest interested in experimenting with the scavenging potential of this new cover crop; however past research has shown inconsistent evidence of this potential being realized because of poor establishment and rapid decomposition of tillage radish. Problems with unpredictable nutrient availability to the following crop could potentially be due to inefficient management tactics. Strategies like applying manure prior to planting and planting mixes that include other annual and winter hardy cover crop species can promote quick and ample fall growth as well as establish a dynamic community of plants that are able to both scavenge as well as serve as a secondary “catch” crop. A replicated, two-phase trial was conducted at the University of Minnesota Southwest Research and Outreach Center from 2014-2017. Establishment and growth of tillage radish alone and alongside annual and winter hardy cover crop species were evaluated amongst tillage and fertility treatments. Cover crops were planted after wheat harvest and followed by a corn crop the following year. Cover crop treatment effect on nutrient availability for the subsequent cash crop was evaluated by measuring soil nutrient status, soil biological activity and potential mineralization throughout the growing season as well as corn crop yield. Each cover crop treatment was tested within three different management systems to represent a legume-based 4 system and two manure-based systems, in addition to two tillage methods: one with tillage prior to planting and the other without. While previously believed that tillage radish establishment and growth is dependent on soil nitrogen, we found tillage after a manure application and prior to cover crop planting yielded twice as much tillage radish biomass with much greater root mass compared with no tillage plots. While the striking differences in fall cover crop growth should have influenced scavenging capacity and nutrient availability, no major treatment differences in available or mineralizable nitrogen were found among neither the system treatments nor the cover crop treatments. Additionally, corn yields for the tilled plots were much greater, especially for the single tillage radish species and tillage radish planted with cover crops that did not overwinter. Further investigation of the impact of soil physical properties and additional benefits related to compaction alleviation are worth investigating to determine how tillage radish improves organic rotations. Furthermore, measurements to determine winter soil cover revealed no differences among tillage treatments in all years. Thus, employing tillage in an effort to increase cover crop biomass should have minimal environmental impact.
Evans, Emily, "Corn (Zea mays L.) yield response to tillage radish (Raphanus sativus L.) when planted with annual and winter hardy cover crops" (2019). Creative Components. 169.