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There is an increasing interest in planting cover crops in the central Corn Belt, primarily as a means of capturing unused nutrients, such as nitrogen, helping to keep those nutrients within the root zone, and making them more available for the following year’s crop.
Two trials were established at the Monsanto Learning Center at Monmouth, IL:
Figure 1. Cover crop comparisons.
The following cover crops were compared:
Plant tissue samples were collected at V4 and VT and tested for plant nutrient content.
Yields in the cover crop plots were compared to untreated checks.
In a separate trial, the impact of seeding cover crops into corn at V7 on corn yield was evaluated.
Figure 2. Some cover crops possess allelopathic characteristics that can stunt crop growth if not managed carefully.
The plant nutrient/yield trial was conducted on 2nd year corn. The previous crop was sweet corn, which was removed the previous fall and cover crops were seeded using a grain drill. Plots were strip tilled in the spring, prior to planting. No burndown herbicide was needed, as winter weather had sufficiently killed the cover crop. Plant tissue samples from the corn crop were taken, comparing nutrient content in the cover crop plots to nutrient content in the untreated check. Corn was harvested in the fall. Yields in the cover crop plots were compared to the untreated check.
Figure 3. This is an index comparing the nutrient content of corn plants in the check plot to corn plants in the cover crop plots. An index greater than 1 indicates higher nutrient content in the check plants. An index less than 1 indicates higher nutrient content in the cover crop plants. This data suggests that, due to the decaying cover crop residue, the relatively immobile nutrients phosphorus (P) and zinc (Zn) were made more readily available to corn plants as the season progressed.
The cover crop seeding trial was conducted on a long-term continuous corn plot. Cover crops were seeded using a high clearance spreader, broadcasting over the plots at the V7 growth stage. Corn was harvested and yields in the cover crop plots were compared to the untreated check.
Figure 4. Broadcasting cover crop seed into corn early in the season led to excellent establishment. However, early cover crop establishment may negatively impact the current crop’s yield potential.
Wander, M., Ugarte, C., Martin, J. 2010. Can we keep soils covered as climate changes? Issue 1.15. University of Illinois at Urbana-Champaign. http://sustainability.illinois.edu. (verified 11/11/14) Singer, J., Kaspar, T., Pedersen, P. Small grain cover crops for corn and soybean. Iowa State University Extension. http://extension.agron.iastate.edu (verified 11/11/14)