Driven by biofuel mandates and high crop prices, grasslands in the northern Plains are being dug up to plant crops at the fastest pace since the 1930s, according to a new study by Christopher Wright and Michael Wimberly of South Dakota University and published in the Proceedings of the National Academies of Science.  The study found that U.S. farmers converted more than 1.3 million acres of grassland into corn and soybean fields from 2006 to 2011.  In states such as Iowa and South Dakota, about 5 percent of pasture is turning into cropland each year.

The author’s of the study concluded that the rates of grassland disappearance is “comparable to deforestation rates in Brazil, Malaysia, and Indonesia.”  Spurred on by the rush to biofuels, corn and soybeans have become such lucrative crops, and with the federal government offering subsidized crop insurance in the case of failure, farmers in Nebraska and the Dakotas are increasingly growing crops on marginal land that is vulnerable to drought.

The loss of grasslands could also have a large environmental impact since grasslands hold carbon better than cropland does.  In addition, wildlife habitats, especially for a number of species of ground-nesting birds, are being disturbed and bird populations are dropping.

However, the authors’ of the study did acknowledge that “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.”