A Half-Century of Yield Growth along the Forty-First Parallel of the Great Plains
研究了美国大平原800英里样带半个世纪的作物产量增长，发现技术进步贡献最大，灌溉和肥料次之，环境变化影响小，且东西部区域差异显著。
<h3>Abstract</h3> We examine a half-century of crop yield growth along an 800-mile transect in the U.S. Great Plains. The main contributors to growth were non-specific technical change +53%, irrigation +26%, fertilizer +13% and chemicals +10%. Environmental changes were small and had a minor impact. The wide range of agroclimatic conditions produced significant sub-regional deviations. Irrigation was important in the more arid and warmer areas of the west, while fertilizer and chemicals were more important in the humid east. Sensitivity to weather has increased in the rainfed regions of the east while it has decreased in irrigated regions of the west.