Recent Land Use Change in the Western Corn Belt Threatens Grasslands and Wetlands
by Christopher K. Wright and Michael C. Wimberly (Proceedings of the National Academy of Sciences) In the US Corn Belt, a recent doubling in commodity prices has created incentives for landowners to convert grassland to corn and soybean cropping. Here, we use land cover data from the National Agricultural Statistics Service Cropland Data Layer to assess grassland conversion from 2006 to 2011 in the Western Corn Belt (WCB): five states including North Dakota, South Dakota, Nebraska, Minnesota, and Iowa. Our analysis identifies areas with elevated rates of grass-to-corn/soy conversion (1.0–5.4% annually). Across the WCB, we found a net decline in grass-dominated land cover totaling nearly 530,000 ha. With respect to agronomic attributes of lands undergoing grassland conversion, corn/soy production is expanding onto marginal lands characterized by high erosion risk and vulnerability to drought. Grassland conversion is also concentrated in close proximity to wetlands, posing a threat to waterfowl breeding in the Prairie Pothole Region. Longer-term land cover trends from North Dakota and Iowa indicate that recent grassland conversion represents a persistent shift in land use rather than short-term variability in crop rotation patterns. Our results show that the WCB is rapidly moving down a pathway of increased corn and soybean cultivation. As a result, the window of opportunity for realizing the benefits of a biofuel industry based on perennial bioenergy crops, rather than corn ethanol and soy biodiesel, may be closing in the WCB. READ MORE and MORE (The Washington Post) and MORE (Renewable Fuels Association) and MORE (Inter Press Service) and MORE (EarthSky)
Excerpt from the Renewable Fuels Association: The study’s findings stand in stark contrast to U.S. Department of Agriculture (USDA) acreage data, which show increased corn and soybean acres in the region have occurred via crop switching, not cropland expansion. Further, the extremely high rate of error associated with the satellite imagery used by the authors renders the study’s conclusions highly questionable and irrelevant to the biofuels policy debate.
Readers of the recent PNAS paper should give strong consideration to the following points:
- Current law strictly prohibits the conversion of sensitive ecosystems to cropland. At least once a year, farmers must certify that they are complying with the highly erodible land conservation and wetland conservation requirements (the so-called “sodbuster” and “swampbuster” provisions) of the Farm Bill. Most producers strictly adhere to conservation plans that are often developed with technical assistance from the Natural Resources Conservation Service.
- Further, the provisions of the Energy Independence and Security Act require that corn and other feedstocks used to produce biofuels for the Renewable Fuel Standard (RFS) may only be sourced from land that was actively engaged in agricultural production in 2007, the year of the bill’s enactment. Feedstock from lands converted to cropland after 2007 would not qualify for the RFS, and thus the program strongly discourages cropland expansion.
- The study’s authors themselves acknowledge that the converted lands they classify as “native grasslands” might actually have been land planted to hay, grass pasture, or idled cropland enrolled in the CRP program. They write, “One shortcoming of the present study was our inability to…distinguish between different types of grassland conversion, i.e. to separate native prairie conversion from change involving CRP, hay lands, or grass pasture.” Thus, the authors’ conclusion that increased corn and soybean acres are coming at the expense of “native prairie” is highly suspect. In fact, USDA data shows decreased hay acres in the region, strongly suggesting that much of the increase in corn and soybean acres came on land previously planted to hay. At the same time, CRP enrollments in the region have declined slightly, suggesting that farmers are bringing some idled cropland back into production.
- Data from USDA show that the increase in corn and soybean acres in the five-state region was primarily achieved via crop switching rather than cropland expansion … READ MORE