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Trindade, F.J., L.E. Fulginiti, and R.K. Perrin. A half century of yield growth along the forty-first parallel of the Great Plains: factor intensification, irrigation, weather, and technical change. University of Nebraska, Lincoln.
In this study, we explain a half-century of crop yield growth along an 800-mile transect of the forty-first parallel North in the U.S. Great Plains. Using 101 county-level observations from 1960-2008 we jointly estimate a biomass production function with cost shares for fertilizer and chemicals while controlling for environmental factors. The main contributors to yield increases in this region were non-specific technical change +62%, irrigation +17%, fertilizer +13% and chemicals +11%. Environmental changes had a minor impact on regional yield changes. The wide range of agroclimatic conditions present along this transect produced significant sub-regional deviations from the aggregate estimates. While technical change was the main source of growth in every region, the contribution of the remaining factors of production varies substantially. Irrigation was almost as important as technical change in the more arid and warmer areas of the west, while fertilizer and chemicals were the second and third most important sources of yield growth in the more humid areas of the east. Temporal variation in contribution shows that climatic sensitivity has increased in the rainfed regions of the west while it has decreased in irrigated regions of the west.