Agricultural Policy, Not Biotechnology, Explains U.S. Trends in Soil Erosion.

Genetically-modified, herbicide-resistant (HR) crops are an ubiquitous and controversial technology in U.S. row crop agriculture. Proponents have argued that HR crops facilitate soil conservation by stimulating adoption of conservation tillage practices. While this claim has been widely repeated in both the scientific and popular media, the hypothesis that HR crops lead to reduced soil erosion has not been rigorously evaluated. We compared U.S. data on adoption of herbicide-resistant corn and soybean with national and regional cropland soil erosion rates and adoption of conservation tillage practices. Since the introduction of glyphosate-resistant corn and soybeans in 1996, HR varieties were rapidly adopted and by 2010 comprised 81% of acreage planted to these two major crops. From 1997 to 2010, average soil erosion rates fell by 6% nationally but increased by 2% in the Corn Belt. More limited data on use of conservation tillage practices reveal weak correlations with HR soybean and corn adoption. Thus, while there may be some association between HR crops and conservation tillage, the historical data do not support the claim that HR crops have led to favorable outcomes for soil conservation. In contrast, average soil erosion rates declined by an impressive 30% nationally, and by 44% in the Corn Belt, from from 1982 to 1997, following the passage of the 1985 Farm Bill, which initiated the Conservation Reserve Program and the Conservation Stewardship Program. Soil conservation has been touted as a primary benefit of genetically-modified, HR row crops. However, these data indicate that improved agricultural policy may be much a much more effective strategy for promoting soil conservation than new biotechnologies.