a four-fold rise - Center for Food Safety

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Center for Food Safety – Science Comments – FG72 Soybean 62 upon long-‐term climate data, inherent soil and site characteristics, and cropping and management practices.” Tillage regimes are the primary component of “cropping and management practices,” and thus play a large role in determining soil erosion rates. It is well established that soil erosion increases with the intensity of tillage, and decreases as farmers adopt regimes that leave more plant residue on the soil (USDA ERS AREI 2002). Thus, the chart below reflects in large degree the tillage regimes used by farmers. From: NRCS (2010), p. 2. On a national basis, water and wind erosion on cropland declined sharply by 38% from 1982 to 1997, from 3.06 to 1.89 billion tons. In the following decade, however, soil erosion almost leveled out, declining by just 8%, from 1.89 to 1.73 billion tons. Herbicide-‐resistant crops were first introduced in 1996, and the area planted to them (HR soybeans, corn and cotton) increased steadily from 16.0 million acres in 1997 to 117.2 million acres in 2007 (Benbrook Supplemental 2009, Table 5). If HR crops promoted adoption of conservation tillage in any significant way, one would surely expect a much stronger decline in soil erosion over a period when their adoption increased by 100 million acres. However, NRCS’ survey offers still more compelling evidence at the regional level. The following map (from p. 3) breaks down average annual soil erosion rates, in tons per acre per year, by farm production region. For each region, rates for the six survey periods (1982, 1987, 1992, 1997, 2002 and 2007) are shown stacked from top (1982) to bottom (2007). The rates in this map are also listed in Table 36 of the report (pp. 12-‐16).
Center for Food Safety – Science Comments – FG72 Soybean 63 The Corn Belt states (Iowa, Illinois, Indiana, Missouri and Ohio) and the Northern Plains states (Kansas, Nebraska, North and South Dakota) comprise two-‐thirds of the nation’s corn and soybean acreage, and all of these states have high adoption rates of GE herbicide-‐resistant soybeans and corn (see USDA-‐ERS 2011a, cited in DEA). If APHIS’ and Bayer CropScience’s supposition that HR crops and HR soybeans in particular promote conservation tillage were correct, one would certainly expect to see an appreciable decline in soil erosion in these two regions over the 1997 to 2007 period when HR versions of these crops were widely adopted; and that decline should be far more pronounced than the national average. However, this is not the case at all. In the Corn Belt states, the annual erosion rate remained constant at 4.1 tons per acre from 1997 to 2007, while erosion actually increased in the Northern Plains states over this same period, from 4.3 to 4.7 tons per acre, in both cases bucking the national trend of modest decline. Of the eight other farm production regions, all but two (Mountain and Lake States) had declining erosion rates. Clearly, the massive adoption of HR corn and soybeans from 1997 to 2007 did not foster increased adoption of soil-‐conserving practices; if it had, it would have been reflected in declining rather than stable or increasing erosion rates.
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a four-fold rise - Center for Food Safety

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