Optimal scheduling of nitrogen fertilization and irrigation

This paper develops and applies a mathematical model for determining the economically optimal scheduling of fertilization and irrigation (fertigation) that maximizes the farmer's profits. The analysis assumes a single crop (corn) and a single growing season. For a given total seasonal fertigation level, the optimal scheduling solution to the optimization problem identifies not only the maximum profits but also the minimum total nitrogen leached below the root zone and, therefore, the minimum groundwater contamination. The conceptual framework, coupled with the experimental data for corn, are used to investigate the impacts of taxing the total nitrogen leaching and an action equivalent taxation of nitrogen fertilizer. It is demonstrated that the increase in the fertilizer tax required to achieve a given level of reduction of total nitrogen leaching is much smaller in relation to the change in the tax on leached nitrogen required to achieve the same reduction.