A History of the Relationship Between Farming and Grassland Wildlife in Illinois: Adding Cover Cropping to the Story

We’ve come a long way from the days when Illinois was one-third forest and two-thirds prairie. At settlement, about 27 million acres of various grassland habitats existed in northern and central Illinois. The most recent USDA Census of Agriculture revealed rural parts of the state contain 71,000 farms with an area of 25.6 million acres, 75 percent of the land area of the state. The composition of Illinois farms is: row crops, 22 million acres; forest, 1.8 million acres; pasture, 724,000 acres; Conservation Reserve Program grassland 594,000 acres; and, small grains, 528,000 acres.

Authorities recognize the importance of wildlife habitat on farms. Though most of these communities could be improved through management, all support respectable numbers of resident and migratory wildlife. Land in corn and soybeans provide waste grain as a food source if fall tillage is limited. However, fall tilled row crop fields are the major source of soil erosion and nutrient and pesticide runoff.

For many decades, Illinois farms were smaller and utilized diverse cropping systems where cropland was covered nearly year around. In the corn belt, the typical crop rotation was corn followed by oats or wheat followed by red clover or alfalfa. Farmers needed small grains and forage crops to feed beef and dairy cattle, hogs and poultry. Agronomists reported the benefits of diverse crop rotations including reduced soil erosion, improved soil quality, added nitrogen, improved water infiltration, suppression of weeds and disrupting disease cycles. These rotations expanded biodiversity, reduced flooding and runoff. They created wildlife habitat and supported beneficial insects.

Illinois agriculture, like other industries, became specialized in the 1960s and most producers in the corn belt abandoned general farming and became row crop specialists. The widespread cultivation of soybeans hastened the move away from diverse crop rotations. The most recent Census of Agriculture reveals that cropland in Illinois is 45 percent corn and 43 percent soybeans. Cash grain agriculture is highly dependent on the export market and more recently on ethanol production as an additive to gasoline.

By the early 1980s, increased grain production resulted in lower grain prices and an increase in grain farm failures. Continuous row crop production also took a toll on the producer’s most valuable assets, the soil. Soil erosion increased as did the application of chemical fertilizers and pesticides creating significant water quality issues. Soils lost biodiversity and became compacted. The loss of small grains, grasses and legumes resulted in a drastic decline in abundance of wildlife associated with grassland.

Falling grain prices and increasing concerns about soil productivity and declining water quality brought about a reappraisal of farm policy emphasizing full production cash grain farming. In 1985, the Conservation Reserve Program (CRP) arrived, to help address these issues. Main objectives of the program were to retire marginal cropland and reduce production of cash grains, all while conserving soil and water resources. The program was successful in accomplishing the primary objectives. In addition, grassland wildlife responded very positively to the significant increase in usable habitat. Although a successful program, the Conservation Reserve Program could have been even more successful with better targeting of enrollments. Soil rental rates were given too much weight in evaluating offers. Offers from areas with relatively minor erosion problems were awarded contracts under the program, while offers from areas with significant problems were rejected because the areas had significantly higher rental rates. Acres were concentrated in the Great Plains when enrollments in the Mississippi River Valley would have had a much greater impact on issues such as hypoxia in the Gulf of Mexico. In addition, early rules permitted the planting of exotic plant materials, such as tall fescue.

The Conservation Reserve Program continues to be the major vehicle for restoring grassland habitat in the United States. But in the last decade demand for cash grain has increased as export markets have returned, and ethanol production has increased. As idled CRP acres were returned to crop production, producers observed remarkable increases in crop yields. Agronomists also took note of increases in yields, the reduction in soil erosion and improvements in water quality, as compared to acreage that had long been under conventional tillage, row-crop production. A number of researchers began experiments to determine if some of the benefits of crop rotations and fallowing could be incorporated into continuous row crop farming. Although longer term rotations with legumes have greater benefits, some significant improvements have been achieved by protecting cropland between harvest and next year’s planting.

The planting of a crop post-harvest and pre-planting the following year became known as cover cropping. Cover crops vary widely in species composition and management around the corn belt. Cover crops have several benefits. By covering the soil surface over winter, soil erosion is reduced. Cover crops that grow throughout the winter capture nitrogen and reduce the runoff of nutrients into water courses. Deep rooted cover crops reduce soil compaction and increase water infiltration.

Cover crops have been proven to improve soil health and water quality, but their benefits for wildlife is a bit complicated. Several studies (Figura 2022, Florence 2016) indicate that the addition of cover crops may enhance use of row crop fields by wildlife. Biologists at the Illinois Natural History Survey documented increased use of harvested cropland by resident and migratory birds in fields with cover crops compared to fields without cover crops. Birds were observed feeding and seeking shelter in fields with cover crops. Cover crops are most beneficial to soils and wildlife when mixtures of small grains and legumes are used. A diverse planting will accommodate more species and provide more shelter and food.

In my area, cereal rye is the most common crop planted after corn is harvested and before soybeans are planted in spring. It provides excellent soil cover and captures nitrogen that could leach into streams. In spring, cereal rye is sprayed with herbicide to eliminate competition with the crop to be planted. Wildlife use of cereal rye increases the longer termination of the cover crop is delayed. With plenty of moisture, cereal rye may grow to 3.5 feet tall before termination. This could be detrimental to ground nesting wildlife. The tall cover may attract wildlife that may have nests destroyed when planting begins.

Studies were conducted in Iowa specifically to evaluate the potential of cover crops to provide nest cover for pheasants and other ground nesting birds. Results of the study indicated that nest densities were 20 times greater in perennial grass cover (CRP) than in cover crop fields, and grassland bird abundance and diversity was greatest in perennial grass cover compared to fields with cover crops and fields without cover crops.

Although fields with cover crops provide food and shelter during fall and winter and possibly brood foraging habitat through the summer season, perennial grass cover of appropriate species, undisturbed from April 1 to August 1, is essential to maintain and increase grassland bird populations. Cover crops show the potential to provide great conservation benefits, but when it comes to grassland wildlife, it can’t replace the benefits provided through perennial grass cover (CRP) or historic, diverse cropping and fallow field rotations

Literature Cited

Figura, M. 2022. Evaluating avian use of cover crops in the corn belt. M.S. Thesis. South Dakota State University, Brookings SD. 75 pp.

Florence, A. 2016. Cover crop mixture, diversity and function. PhD Dissertation. University of Nebraska, Lincoln NE. 125 pp.

Shirley, T. R. and A. K. Janke. 2023. Ring-necked pheasant nest site selection in a landscape with a high adoption of fall seeded cover crops. Wildlife Society Bulletin.10.1002/wsb.1521, 48, 2, (2024).

Wilcoxen, C. A., J. W. Walk and M. P. Ward. 2018. Use of cover crop fields by migratory and resident birds. Agriculture Ecosystems and Environment. 252. 42-50.

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John Cole grew up in Bradley (Kankakee County). He graduated from SIU Carbondale with BA in 1968 then served two years in the U.S. Army as medical technologist at Tripler Army Medical Center in Honolulu. After graduating from SIU Carbondale with an MS in 1973 he began to work for the then Illinois Department of Conservation as District Wildlife Biologist, headquartered in Gibson City in east-central Illinois. In 1993, Cole became the Illinois Department of Natural Resources Ag and Grassland program manager in Springfield, working there until his retirement in 2008.