Biofuels program destroying grasslands in American Midwest

A new study by researchers at South Dakota State University, published in the Proceedings of the National Academies of Science (see full paper here), shows that more than 1.3 million acres of grasslands in the western corn belt (WCB) of North Dakota, South Dakota, Minnesota, Iowa, and Nebraska, have been converted to agricultural use since 2006 to grow corn and soybeans for biofuel production.

The researchers introduce their paper by writing:

“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)…”

They go on to write:

“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.[hectares]. 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.”

“The concentration of grassland conversion on lands vulnerable to erosion implies negative impacts on soil quality and a subsequent cascade of negative impacts on, e.g., crop yields, primary productivity, and carbon sequestration. Tillage of adjacent uplands increases sediment inputs to wetlands by several orders of magnitude, limiting the productivity of duck food sources, including aquatic plants and invertebrates, and reducing food water storage.”

In the conclusion, the researchers note:

“Our results show that rates of grassland conversion to corn/soy (1.0–5.4% annually) across a significant portion of the US Western Corn Belt are comparable to deforestation rates in Brazil, Malaysia, and Indonesia, countries in which tropical forests were the principal sources of new agricultural land, globally, during the 1980s and 1990s. Historically, comparable grassland conversion rates have not been seen in the Corn Belt since the 1920s and 1930s, the era of rapid mechanization of US agriculture. Across the WCB, more than 99% of presettlement tallgrass prairie has been converted to other land covers, mostly agricultural, with losses in Iowa approaching 99.9% of an original 12-million ha. of tallgrass prairie. Potential expansion of corn and soybean cultivation into remaining fragments of tallgrass prairie in the WCB presents a critical ecosystem conservation issue.”

This is another example of so-called “green energy” being not so green. As the authors note, ” A number of studies have now shown that a biofuel strategy based on corn ethanol and soy biodiesel may indeed be suboptimal in terms of net energy and carbon balances.”

See also:

Ethanol fuel not as green as you think

Ethanol from Sugarcane, not so green

Death Toll from Biofuels