The United States Government Accountability Office (GAO) has found that native grassland continues to decline in the U.S., particularly in South Dakota where relatively high subsidies are offered to farmers who convert grassland to cropland.

The GAO says analysis shows that farm program payments are an important factor in whether grassland is converted to grow crops. A 2006 study by the United States Department of Agriculture, for example, revealed a link between crop insurance subsidies expanding cropland.

Farm subsidies are not the only reason why native grasslands are diminishing, stresses the GAO. "Certainly other factors, including rising crop prices - largely spurred by increased ethanol demand - and the emergence of genetically modified crops and new farming techniques that make cropping on heretofore unsuitable land possible are also important in producers decisions", says the report.
 
Nonetheless, there is an apparent incoherence between certain farm subsidies, with some promoting conservation and others the conversion of grassland to cropland.

The report notes that in South Dakota, 1.6 million acres were enrolled in the Conservation Reserve Program during the 1982-1997 period. At the same time, 1.82 million acres of grassland were converted to cropland.

The GAO recommends further research on the role that farm subsidies are playing in the conversation of grassland to cropland.
 
"Farm Program Payments Are an Important Factor in Landowners' Decisions to Convert Grassland to Cropland," is available on-line at: http://www.gao.gov/highlights/d071054high.pdf