Simulating county-level crop yields in the Conterminous United States using the Community Land Model: The effects of optimizing irrigation and fertilization

Abstract

In this study, we applied version 4.5 of the Community Land Model (CLM) at a 0.125° resolution to provide the first county-scale model validation for simulating crop yields over the Conterminous United States (CONUS). Large bias was found in simulating crop yields against U.S. Department of Agriculture (USDA) survey data, with county-level root-mean-square error (RMSE) of 42% and 38% for simulated US mean corn and soybean yields, respectively. We then synthesized crop yield, irrigation and fertilization data sets from USDA and U.S. Geological Survey (USGS) to constrain model simulations. Compared with fertilization, irrigation has limited effects on crop yields with improvements limited to i..