Climate and management contributions to recent trends in U.S. agricultural yields

Lobell, D. B.; Asner, G. P.

The relationship between climate variation and maize and soyabean production in the USA was studied based on temperature, precipitation, solar radiation, and crop yield data from two regions (a large area centred in the Midwest where yields were favoured by cooler and wet years, and a smaller region, including the Northern Great Plains, favoured by hotter and drier years) during 1982-98. Yield trends for both crops were significantly correlated with temperature variation. Approximately 25% of maize and 32% of soyabean yield trends could be attributed to temperature variation during the 17-year period. Regression analysis indicated that maize and soyabean yields decreased by approximately 17% for each degree increase in growing season temperature. The variation in precipitation and solar radiation did not significantly affect yields.