University of Wisconsin Study Based on Shaky Foundation of Faulty Data and Conclusions

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April 13, 2015

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by Geoff Cooper (Renewable Fuels Association) A recent study published in Environmental Research Letters by authors at the University of Wisconsin uses error-prone satellite data to suggest that growth in U.S. corn and soybean production from 2008 to 2012 drove massive conversion of grassland, forest, and other “native” lands to cropland.[1] The authors attribute these purported land conversion events, in part, to “increased demand for biofuels.”

However, contrary to the study’s results, there is no empirical evidence to support the argument that U.S. cropland has expanded since 2008, let alone that large tracts of native grassland and forest have been converted to crops. In fact, USDA data clearly show that the area planted to field crops was more than 1 million acres smaller in 2012 than in 2008.

Indeed, the natural conclusion suggested by USDA acreage data is that increases in corn and soybean production have been accommodated through “crop switching” and higher yields per acre—not through conversion of non-agricultural lands. Increased corn and soybean acreage has been largely offset by reductions in the amount of acres planted to wheat, sorghum, hay, and other crops. Further, some previous cropland enrolled in the Conservation Reserve Program (CRP) has returned to crop production.

USDA Data Dispute Study Findings

The study’s authors suggest that net U.S. cropland expanded by 2.98 million acres from 2008 to 2012. Yet, USDA data show a net reduction in area planted to field crops (i.e., “planted cropland”) between 2008 and 2012.[2] Planted cropland totaled 325.6 million acres in 2008, fell in successive years through 2011, then rebounded to 324.3 million acres in 2012—still more than 1 million acres below 2008 levels.[3]

Thus, while the amount of cropland planted to corn and soybeans increased by 12.8 million acres from 2008 to 2012, cropland planted to all other field crops fell by 13.5 million acres—more than offsetting the increase in corn and soybeans.

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In the end, the authors of the Wisconsin paper fail to explain why their land use results—derived from highly suspect satellite data analysis—differ dramatically from official data reported by USDA’s National Agriculture Statistics Service. The authors suggest cropland has expanded on both a gross and net basis at the expense of grassland, forest and other native lands. Yet, there is little or no evidence in USDA’s widely used data sets that this has in fact occurred, nor is even sufficient anecdotal evidence to substantiate the study’s claims. Instead, USDA data show that the long-term national trend toward less planted cropland persisted following passage of the expanded Renewable Fuel Standard in 2007, and that increases in corn and soybean acres were accommodated through crop switching.

[1] T.J. Lark, J.M. Salmon, and H.K. Gibbs. Cropland expansion outpaces agricultural and biofuel policies in the United States. Environ. Res Lett. 10 (2015) 044003. Doi:10.1088/1748-9326/10/4/044003.

[2] U.S. Dept. of Agriculture, National Agriculture Statistics Service. Field crops include all principal planted crops (barley, beans, canola, corn, cotton, flax, hay, haylage, hops, lentils, millet, mustard, oats, peanuts, peas, potatoes, rapeseed, rice, rye, safflower, sorghum, soybeans, sugarbeets, sugarcane, sunflower, taro, tobacco, and wheat.

[3] See NASS, Statistics by Subject: Crops: Field Crops.http://www.nass.usda.gov/Statistics_by_Subject/index.php?sector=CROPS

[4] See:http://www.agcensus.usda.gov/Publications/2012/Full_Report/Volume_1,_Chapter_1_US/st99_1_008_008.pdf