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Opportunities with Interseeding

Our goal with the design of the interseeder was to develop an affordable machine that could do the interseeding effectively as well as improve the application of the fertilizer and herbicide.
Figure 2. Interseeded clover during midsummer under the corn canopy.

Figure 2. Interseeded clover during midsummer under the corn canopy.

To address this issue, we developed a machine in conjunction with Penn State Agronomy Research Farm to facilitate interseeding in no-till and reduced tillage corn crops. The machine uses coulter tillage in the row to prepare a shallow seedbed followed by packing wheels and a drag chain to incorporate the seed. Since interseeding often coincides with sidedressing and postemergent herbicide applications, we added the capability of applying N fertilizer next to the corn row and applying herbicide to the machine.

In 2010, we initiated several studies evaluating the potential of interseeding cover crops in corn using the newly developed machine. Our initial studies with interseeding cover crops have been positive. We established two studies to evaluate the potential of seeding several cover crop species at sidedressing (V7 growth stage of corn). We were able to successfully establish ryegrass, red clover, white clover and a red clover/ryegrass mixture in no-till corn following both corn and soybeans. There was no significant impact on yield. Since the establishment of the crop is after the “critical weed free period” in corn, the expected impacts on yield are likely to be small. Future studies will attempt to duplicate these results and will assess the impact of the cover crops on subsequent crop yields.

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Figure 3. Interseeded ryegrass/clover cover crop growth in April that could be grazed.

Characteristics of the ideal interseeding species may be different that those for more traditional cover crops. Species or varieties that can emerge with minimal moisture, can tolerate the heat and shade in these environments, and can provide good fall growth and winter cover are ideal. Also refining the ideal seeding rates for this system in our environment is also critical. Lower seeding rates could reduce the cost associated with the cover cropping system and also allow for inclusion of more species in the cover crop mix if desired. Earlier seeding dates could have more potential in shorter season environments or in fields where fall grazing and forage production has some potential.

Another timely potential benefit is the potential for improved nutrient recycling. There should be potential for improving the nutrient retention of mobile nutrients such as N, S and even P and K, as noted in some previous research. Grasses are vigorous competitors for soil K and could help to extract soil K for use by subsequent crops. Interseeded legumes could fix nitrogen, which could be used by subsequent crops.

The potential of fall grazing corn stalks is another application that could be attractive to some producers. A ryegrass or ryegrass/clover cover crop could provide a nice complement to grazing corn stalks for beef or sheep animals. Grazing could be done in the fall or early spring. It may be necessary to fertilize the cover crop late in the summer to maximize the potential dry matter production in this system.

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Figure 4. Planting corn in an interseeded corn stubble field.

An interseeded cover crop could be especially useful where corn stalks are removed for bedding or other uses. In these fields, removal of carbon in the stalks can be an issue and could eventually lead to lower soil organic matter levels. Soil erosion can also be an issue on these fields unless a cover crop is established, which is difficult in northern counties. An interseeded cover crop could help to alleviate both of these issues.

Finally, an interseeding may also be able to minimize the potential yield impact of growing corn following corn, which is common in Pennsylvania. In interseeded fields, second year corn could be planted into a legume grass mix, for example, which is a much different environment than corn stubble. If the interseeding is done only in row middles, then the second year of corn can be planted next to the original corn rows and avoid the problem of planting into a dense cover crop.

Another interesting issue is the potential impact of the cover crops on the development of weed species in corn fields. It is likely that a vigorous interseeded cover crop could minimize the development of some late emerging winter annual weed species that are becoming a problem in row crops. A Canadian group, Abdin et al. (2000), indicated that interseeded cover crops complemented cultivation in providing weed control in corn.

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Opportunities with Interseeding

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