Yield potential and resource-use efficiency of maize systems in the western U.S. Corn Belt

Unlike the Central and Eastern U.S. Corn Belt where maize is grown almost entirely under rainfed conditions, maize in the Western Corn Belt is produced under both irrigated (3.2 million ha) and rainfed maize (4.1 million ha) conditions. Simulation modelling, regression, and boundary-function analysis were used to assess constraints to maize productivity in the Western Corn Belt. Aboveground biomass, grain yield, and water balance were simulated for fully-irrigated and rainfed crops, using 20-year weather records from 18 locations in combination with actual soil, planting date, plant population, and hybrid-maturity data. Daily mean temperature and cumulative solar radiation were estimated for three growth periods (preand post-silking, and the entire growing season) and used to identify major geospatial gradients. Linear and stepwise multiple regressions were performed to evaluate variation of potential productivity in relation to meteorological factors. Boundary functions for the relationship between productivity and seasonal water supply or crop evapotranspiration were derived and compared against observed data reported in the literature. Geospatial gradients of seasonal radiation, temperature, rainfall, and evaporative demand along the Western Corn Belt were identified. Yield potential with irrigation did not exhibit any geospatial pattern, 1 This chapter previously published as: Grassini, P., Yang, H., Cassman, K.G., 2009. Limits to maize productivity in Western Corn Belt: a simulation analysis for fully irrigated and rainfed conditions. Agric. For. Meteor. 149, 1254-1265.