Wednesday, November 7, 2007
309-3

Rye Cover Crops in a Corn Silage-Soybean Rotation.

Thomas Kaspar and Jeremy Singer. USDA/ARS National Soil Tilth Laboratory, 2150 Pammel Drive, Ames, IA 50011-4420

Corn silage is often grown in the Upper Midwest to provide feed for cattle.  Silage harvest, however, does not leave enough crop residue to adequately protect the soil from erosion and can reduce soil organic matter.  Winter cover crops planted after silage harvest and after other crops in the cropping system can provide erosion protection and help to maintain soil organic matter.  A 5-yr experiment was conducted in central Iowa to determine the amount of shoot biomass that is produced by a rye winter cover crop planted after corn silage harvest and the effect of a rye winter cover crop on soybean and corn silage yield.  Averaged over 5 yr, a rye winter cover crop produced 2.94 Mg ha-1 of shoot biomass following corn silage compared with 1.28 Mg ha-1 following soybean.  Undoubtedly, the earlier planting date of the rye cover crop following corn silage contributed to the difference in biomass.  Previous studies had shown a grain yield decrease when corn followed a rye winter cover crop.  Similarly, in this study, corn grain yield was 0.3 Mg ha-1 less following a rye cover crop (12.1 Mg ha-1 vs.12.4 Mg ha-1).  Corn silage biomass and soybean grain yield, however, were not reduced in this study.  Corn silage biomass averaged over 4 yr was 16.9 Mg ha-1 either with or without a cover crop.  Soybean grain yield averaged over 4 yr following a rye cover crop was 3.6 Mg ha-1 compared with 3.7 Mg ha-1 without a cover crop.  This study indicates that a rye winter cover crop can produce substantial shoot biomass following corn silage harvest and that corn silage and soybean yields following a rye winter cover crop are not reduced.