Understanding the Value of Tillage Radish and Perennial Cover Crops As Nutrient Sources for Field Crops.

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 oilseed 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 the rapid decomposition of tillage radish. A replicated, three phase trial at the University of Minnesota Southwest Research and Outreach Center is in the third year of experimentation. Establishment and growth of tillage radish alone and within annual and perennial species have been evaluated amongst tillage and fertility treatments. Cover crops were planted after wheat harvest, followed by a corn crop the following year. Cover crop treatment effect on nutrient availability for the subsequent cash crop is evaluated by measuring soil nutrient status and potential mineralization throughout the growing season as well as performance of subsequent cash crop yield. All treatments were measured against the typical red clover seeding used by many area farmers. While previously believed that tillage radish establishment and growth is dependent on soil nitrogen, we found tillage prior to planting yielded twice as much tillage radish biomass, with much larger root masses. This makes a big difference for scavenging capacity and additional benefits related to compaction alleviation. Subsequent corn yields for these tillage treatments were also higher, however, only for the single tillage radish species and species containing other annual cover crops.