Cover Crops and Conservation Tillage
for Soil Erosion Control on Cropland

Table of Contents

Rotations in Established Crownvetch

Soybean after corn - Rotations in Established Crownvetch

Soybeans are best planted into birdsfoot trefoil and crownvetch only when the cover crop will tolerate a chisel plow or some tillage without being wiped out. Roundup plus Sencor is the only effective herbicide mixture for suppression of birdsfoot trefoil and crownvetch in soybean and the soybean must be planted with a corn planter in wide (30-inch) rows in order to prevent a dense soybean canopy from smothering the cover crop. Traditional soybean herbicides with residual activity will be needed at planting time to provide some early season weed control and to reduce the need for Roundup as a post treatment. Ideally Roundup or Touchdown should be part of the preemergence treatment so the cover crop isn't clobbered twice with a pre treatment followed by a postemergence Roundup. Use any of the herbicides suggested for use in the Penn State Agronomy Guide. None of the residual soybean herbicides effectively suppress healthy crownvetch, so without some tillage or Roundup + Sencor, crownvetch quickly can become a weed in soybean. Classic, Lorox, Sencor or Lexone are very hard on birdsfoot trefoil but without their use birdsfoot trefoil may very well be too competitive also. See Table 6 for weed control recommendations.