Spatial Dynamics of Water and Nitrogen Management in Irrigated Agriculture

Dynamic optimization of crop production with nonuniform irrigation and nitrogen carryover and leaching is considered. A production function system with thresholds, plateau maximum, and yield reduction is estimated from experimental data; rapid convergence to a steady-state is observed. Spatial variability implies a 40% increase in applied water and a six-fold increase in nitrate emissions, while dynamic optimization has more modest impacts. Nitrate emission control is accomplished primarily through reduced applied water, illustrating a strong cross-policy effect. Significant levels of water conservation and nitrate pollution control are achieved at relatively low cost with traditional irrigation systems and baseline conditions. Copyright 2008, Oxford University Press.