Try a Cover Crop for Fields Unplanted this Spring

In Ag.com today, Successful Farming writer Jeff Caldwell advises those with empty fields this July, because of earlier flooding and rain, to consider a summer cover crop. Here’s the article, and here’s a link to the page:

If flooding kept you out of the field this spring and you weren’t able to plant, don’t just leave that land bare all year, says one agronomy specialist.

If you’re filing a Prevented Planting crop insurance claim on some of your acres this year, you’ll presumably be unable to get into the field to get anything sown too soon. But, that doesn’t mean you can just leave those acres untended. One good strategy, says Purdue University agronomist Eileen Kladivko, is to plant a cover crop. The benefits are many, she says.

“To rebuild lost productive capacity and improve soil quality, growing a cover crop for the remainder of the season is crucial,” Kladivko says in a university report. “In fact, having something green and growing during all non-frozen times of the year is a key concept for improving soil quality, decreasing nitrate leaching to drainage waters, and improving water quality.”

How to cover crops help keep the soil in good shape? Kladivko says there are 3 main ways:

  1. Improve soil tilth and biological activity in topsoil
    Cover crops protect the soil from further erosion by both water and wind. High biomass cover crops help build soil organic matter, improve soil aggregation, and stimulate soil biological activity by adding their roots and shoots to the soil.
  2. Increase permeability and decrease compaction
    Deep rooted cover crops can penetrate compacted layers and provide deep, continuous channels for water percolation and root penetration of subsequent cash crops.
  3. Build soil nitrogen
    Cover crops can build soil nitrogen by fixing atmospheric N (legumes) or by trapping residual soil N to prevent it from leaching into drainage waters.

Which cover crop’s right for your fields? First, figure out what the crop’s main purpose will be. Do you want more biomass above or below the soil’s surface? What weather conditions will the crop face during critical growth stages? What are your soil’s nutrient needs during the season? These are all key questions to ask.

“Grasses usually provide the greatest amount of biomass both below and above ground and will build soil organic matter most quickly. Summer grasses such as sorghum-sudangrass and millets are good choices for early summer plantings while the more familiar annual ryegrass and cereal grains can be planted mid- to late-summer,” says Kladivko. “Legumes will fix atmospheric nitrogen that can be used by next year’s cash crop. Cowpeas are an excellent choice for mid-summer plantings, while hairy vetch, crimson clover, and winter peas can be planted through late summer. Be sure to inoculate all legume seed. Brassicas such as oilseed radish, turnip, rapeseed and canola have tap roots that help break up tillage pans and improve permeability while being an excellent nitrogen scavenger and can be planted mid- to late-summer.”

But, what about when winter hits? Do you want your cover crop to be around until spring, or will having to tear them out next year make more work for you during the busy planting season?

“The advantage of those that winterkill is that the producer does not need to terminate them in the spring, but the overwintering species will continue to provide some additional growth and benefit next spring,” Kladivko says. “Some summer planted cover crops may need to be managed by mowing or killing before seedhead formation to prevent them from becoming a weed next year. If residual herbicides were applied this year, producers should consult herbicide labels for plant back restrictions, as some covers are sensitive to some of the residual herbicides.”

There are a couple other considerations if you’re putting in a cover crop on acres you’ve claimed for Prevented Planting. First, check with your local FSA office and crop insurance agent about any potential restrictions for the management of cover crops on prevented-plant acres in your area, specifically regarding harvest. Then, when you go to plant the crop, make sure you seed it so it thrives in once-flooded soils.

“For prevented planting conditions it is best to seed the cover crop with a drill or planter to assure good soil seed contact,” Kladivko says. “This is especially important given the crusted, hard top soil often present after prolonged soil ponding.”

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