We investigate the effect of crop price and climate variables on rainfed corn and soybean yields and acreage in the United States using a large panel dataset for the 1977–2007 period. Instrumental variables are used to control for endogeneity of prices in yield and acreage regressions, while allowing for spatially auto‐correlated errors. We find that an increase in corn price has a statistically significant positive impact on corn yield, but the effect of soybean price on soybean yields is not statistically significant. The estimated price elasticities of corn yield and acreage are 0.23 and 0.45, respectively. Of the increase in corn supply caused by an increase in corn price, we find that 33.8% is due to price‐induced yield enhancement and 66.2% is due to price‐induced acreage expansion. We also find that the impact of climate change on corn production ranges from −7% to −41% and on soybean ranges from −8% to −45%, depending on the climate change scenarios, time horizon, and global climate models used to predict climate change. We show that the aggregate net impact of omitting price variables is an overestimation of the effect of climate change on corn yield by up to 9% and on soybean yield by up to 15%.
This study integrates a biophysical model with a county-specific economic analysis of breakeven prices of bioenergy crop production to assess the biophysical and economic potential of biofuel production in the Midwestern United States. The bioenergy crops considered in this study include a genotype of Miscanthus, Miscanthus  giganteus, and the Cave-in-Rock breed of switchgrass (Panicum virgatum). The estimated average peak biomass yield for miscanthus in the Midwestern states ranges between 7 and 48 metric tons dry matter per hectare per year ( t DM ha À1 yr À1), while that for switchgrass is between 10 and 16 t DM ha À1 yr À1. With the exception of Minnesota and Wisconsin, where miscanthus yields are likely to be low due to cold soil temperatures, the yield of miscanthus is on average more than two times higher than yield of switchgrass. We find that the breakeven price, which includes the cost of producing the crop and the opportunity cost of land, of producing miscanthus ranges from $53 t À1 DM in Missouri to $153 t À1 DM in Minnesota in the low-cost scenario. Corresponding costs for switchgrass are $88 t À1 DM in Missouri to $144 t À1 DM in Minnesota. In the high-cost scenario, the lowest cost for miscanthus is $85 t À1 DM and for switchgrass is $118 t À1 DM, both in Missouri. These two scenarios differ in their assumptions about ease of establishing the perennial crops, nutrient requirements and harvesting costs and losses. The differences in the breakeven prices across states and across crops are mainly driven by bioenergy and row crop yields per hectare. Our results suggest that while high yields per unit of land of bioenergy crops are critical for the competitiveness of bioenergy feedstocks, the yields of the row crops they seek to displace are also an important consideration. Even high yielding crops, such as miscanthus, are likely to be economically attractive only in some locations in the Midwest given the high yields of corn and soybean in the region.
OBJECTIVEThe landmark Diabetes Prevention Program (DPP) showed that lifestyle intervention can prevent or delay the onset of diabetes for those at risk. We evaluated a translational implementation of this intervention in a diverse set of American Indian and Alaska Native (AI/AN) communities.RESEARCH DESIGN AND METHODSThe Special Diabetes Program for Indians Diabetes Prevention (SDPI-DP) demonstration project implemented the DPP lifestyle intervention among 36 health care programs serving 80 tribes. A total of 2,553 participants with prediabetes were recruited and started intervention by 31 July 2008. They were offered the 16-session Lifestyle Balance Curriculum and underwent a thorough clinical assessment for evaluation of their diabetes status and risk at baseline, soon after completing the curriculum (postcurriculum), and annually for up to 3 years. Diabetes incidence was estimated. Weight loss, changes in blood pressure and lipid levels, and lifestyle changes after intervention were also evaluated.RESULTSThe completion rates of SDPI-DP were 74, 59, 42, and 33% for the postcurriculum and year 1, 2, and 3 assessments, respectively. The crude incidence of diabetes among SDPI-DP participants was 4.0% per year. Significant improvements in weight, blood pressure, and lipid levels were observed immediately after the intervention and annually thereafter for 3 years. Class attendance strongly correlated with diabetes incidence rate, weight loss, and change in systolic blood pressure.CONCLUSIONSOur findings demonstrate the feasibility and potential of translating the lifestyle intervention in diverse AI/AN communities. They have important implications for future dissemination and institutionalization of the intervention throughout the Native American health system.
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