Summer Seeded Cover Crops 1996-1999

Leguminous cover crops are potentially important phases in rotations due to their beneficial effects on soil nutrients, organic matter accumulation and the prevention of erosion. These cover crops can be planted with or subsequently to a small grain which is harvested midway through the growing season. Although cover crops are cheaper to frost seed into winter wheat or companion seed with spring-seeded small grains, many farmers in the upper Midwest prefer seeding cover crops following small grain harvest. This is due to their concern that the cover crops can adversely affect straw quality. Frequently, clean small grain straw will add $70-$100/acre to the value of the crop (60 bu/a wheat; 100 bu/a oats). The recommended summer-seeded option however, is expensive ($30/a seed costs) so it is necessary to look for other alternatives.

The second issue to be addressed in these trials dealt with the speed of re-establishing ground cover after the cover crop planting. NRCS officials were concerned that a new planting of cover crops would disturb the existing ground cover of the small grain residue (personal communication J. Pingry, 1996). As a result, in an effort to increase biologically fixed nitrogen in the rotation, one could inadvertently increase the potential for soil erosion in the late summer.

In order to address these two issues of summer seeded cover crop options and tillage methods for sequential seeding, a three-year study was initiated at Arlington in August, 1996. In 1996, 1997 and 1998 cover crop plots were planted and evaluated. In all 3 years, corn was planted over the previous year’s cover crops to measure the yield effect of the plowdown green manure.

Authors: J. Posner, J.L. Hedtcke, S.G. Alt, J.K. Stute