Most commonly used cover crops in Iowa

Iowa State University Extension
Sprouts of red clover peak through the soil.

Now is the time to make plans for cover crop planting if you have not already done so.

There are several cover crop species that are often talked about; however, cereal rye, oats and radish are the most commonly used cover crops in the state. Hairy vetch, red clover, cowpea, rapeseed, winter wheat, triticale and annual ryegrass all get mentions.

Choosing which to use is dependent on your goals, how and when you are going to plant and your corn and soybean management practices.

Biomass production

Biomass production is typically associated with soil health, reduce soil erosion and nutrient loss reduction benefits. More biomass production equates to more benefits.

In general, winter and spring small grain species provide the most amount of biomass following corn and soybean crops. If seed corn production and corn silage fields are being targeted, there is much greater opportunity for legumes and brassicas to be added into the cropping system for biomass production but also ancillary benefits of alleviating soil compaction or nitrogen fixation.

Overwintering

Cereal rye and triticale are the most dependable cover crops to overwinter.

Winter wheat, red clover and hairy vetch can overwinter with adequate fall growth and suitable winter weather conditions. Most often the brassica species do not overwinter, but some brassicas have a small percentage of the seed lot that will germinate and grow in the spring.

Nitrogen fixation

Nitrogen fixation is limited to legumes, and even then, they need to be planted early and have a good overwintering capability in order to produce enough nitrogen to justify higher seed costs and possible alterations to corn hybrid maturity or harvesting of corn at a higher grain moisture.