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Cover Crops Have Underused Potential As Conservation Tool

A wealth of scientific information exists on the benefits of cover crops, yet their use in conventional row-crop farming systems traditionally has been low.

To learn more about cover-crop use in the central western Corn Belt,  the National Soil Tilth Laboratory developed a survey that was mailed 5 years ago to 3,500 producers in Iowa, Minnesota, Illinois and Indiana. In addition to the questions about why farmers did or did not use cover crops, they asked them about their farm type and size, familiarity with cover crops and use of other conservation practices.

Survey results confirmed that cover-crop adoption in these states is low. Only 10.5% of the respondents in Iowa had ever planted cover crops, defined as any plants that cover the soil and are planted after the main cash-crop growing season. Only 6% of the Iowa respondents had planted them within the past 5 years.

In Iowa, 28% of the respondents said they were not at all familiar with cover crops and 28% said they were either very familiar or moderately familiar with this practice.

The highest rate of cover-crop use was 28% in Indiana, which typically has a longer growing season and window to plant and establish a cover crop. In both Illinois and Indiana, 15% of the respondents had planted cover crops in the past 5 years.

Perceived Obstacles. When asked why they had never planted cover crops, farmers were asked to choose from several reasons (which are calculated for this analysis by state). Responses included:

• Don’t know enough about them to know if it’s right for my farm, 22% to 34%
• Too much time involved, 21% to 30%
• I don’t have a runoff problem, 19% to 23%
• Already use no-tillage practices, 17% to 35%
• Too costly, 14% to 24%
• Cover crops reduce crop yield, 1% to 8%.

Based on these results, time constraints, profitability and yield depression in subsequent cash crops do not appear to be significant impediments to cover-crop adoption. Developing good cost estimates for cover-crop establishment and cover-crop management and uses may help producers determine the benefits and risks of using cover crops in farming systems dominated by summer annual crops.

Perceived Benefits. Farmers were asked about what they perceive to be the main benefits of cover crops. Between 84% and 87% listed a reduction in the amount of soil erosion, followed by an increase in soil organic matter at 60% to 71%. Other perceived benefits included a reduction of soil compaction and weed suppression.

Willingness To Use Them. When asked about using cover crops if cost-sharing was available, 40% to 58% of the respondents said they would use them. Between 47% and 62% of the respondents said they had a grain drill or other equipment to plant cover crops, and 24% to 30% said they would use cover crops if they could custom hire the planting.

Most Desirable Traits. Farmers were asked about characteristics they would look for in a cover crop. Desirable plant traits included:

• Nitrogen fixation, 43% to 56%
• Fall plant residue, 38% to 52%
• Spring plant residue, 20% to 29%
• Winterkill (for weed suppression), 19% to 25%.

Common Covers. Among cover-crop choices, winter wheat was more popular in Illinois and Indiana; winter rye was common in Illinois, Indiana and Iowa; and oats was common in Iowa and Minnesota. Red clover was the most common legume cover crop, appearing more often in Illinois and Indiana.

Cover-crop adoption and the cover crop used reflect the different farming systems in each state. More wheat is grown in Illinois and Indiana than Iowa, so producers may save some of their wheat seed to plant a cover crop. Producers from these states also could have counted their cash grain wheat crop as a cover crop, although the survey defined cover crops as plants grown between cash crops.

The higher incidence of red clover in Illinois and Indiana also reflects the use of the red clover as an intercrop in wheat, which is a good source of nitrogen for a subsequent corn crop. Longer growing seasons in Illinois and Indiana also may contribute to increased cover-crop use.

Conclusions. The results of this survey will be used to identify cover-crop knowledge gaps and improve the dissemination of cover-crop information. Cover crops may become more important in midwestern farming systems as producers add corn acreage with corn following corn becoming more common.

Cover crops may alleviate some of the yield depression that is documented in continuous corn, and continue to accumulate nutrients after the cash crop is harvested.

Educational programs and targeted cover-crop use on vulnerable sites in the landscape may increase cover-crop adoption and contribute to protecting our natural resource base and maintaining productive soil.

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