Seeding a cover crop after wheat harvest

What are my choices for seeding a cover crop after wheat harvest?

Since we have had an early harvest of our wheat this year (2012), we have a large window to plant cover crops. The biggest concern this year is dry soils. Successful cover crop establishment will require adequate moisture.

Farmers that have irrigation can establish cover crops by providing water. The irrigation will give the cover crops a jump on the weeds. One way to conserve moisture is to no-till your cover crops into the wheat stubble. When no-tilling, we recommend a weed-free field. If you use tillage for your weed control in harvested wheat, you can expect wheat to regrow.

Currently in southwest Michigan the soils are so dry, seeding a cover crop is not recommended. The good news is that we still have time for the rains to come and plant cover crops.

Here are some of my recommendations for seeding cover crops after wheat.

Non-legume cover crops

Oil seed radish (OSR). We have had our best results when we seed this the first week to the middle of August. OSR responds extremely well to residual nitrogen. Due to the drought, we should have residual nitrogen in many of our wheat fields. OSR has also responded extremely well to manure. Over the past several years, Tim Harrigan of MSU’s Department of Biosystems and Agricultural Engineering and I have manure slurry-seeded OSR with excellent results. In our studies, slurry seeding has provided benefits when the soils have been dry and there has been limited rainfall.

OSR will winterkill unless we have another unusual winter like last year.

Oats are our most economical cover crop and, similar to OSR, they responded to residual nitrogen in the soil. You can plant oats any time the soil moisture level is adequate. Oats will winterkill.

Annual ryegrass (AR) is a cover crop that will also recycle nitrogen. AR produces a massive roof that can help build soils. The biggest complaint about AR is that it can be hard to control in the spring. AR will overwinter most winters in Lower Michigan.

Legume cover crops

Crimson clover (CC) an annual red clover that can successfully be seeded after wheat. Since it is an annual, it will germinate and grow faster than the biennial red clovers. CC will not provide as much nitrogen as the other red clovers, though. In most Michigan winters, it will overwinter, especially with adequate snow cover.

Medium or mammoth red clover (RC). This year, due to the early harvest of wheat, these popular RC could be planted. Again, seeding RC in August is risky because it doesn’t have enough time to produce a lot of biomass. When you get into the middle of August, I recommend changing red clover species to crimson clover.

Austrian winter pea (AWP)could be planted this year. AWP will provide you with nitrogen, however, not as much as RC. AWP seed is larger than RC and shipping cost for seed can sometimes be a concern.

Cocktails (crop combinations)

OSR + oats. This combination is popular in parts of the state.

Crimson clover + annual ryegrass. Several areas in the state are using these combinations.

OSR + rye. This combination is being evaluated by several farmers.

Again, we need moisture and a clean field to establish cover crops. To help you make good cover crop selections, you can use the cover crop selection tool developed by MSU Extension’s Dean Baas, found at the Midwest Cover Crops Council website.

Related MSU Extension News article: Managing red clover that was frost-seeded into wheat

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