Optimal timing and rate of nitrogen fertilizer use: An integrated network technology approach

Both the rate and timing of crop fertilizer application play an important role in agricultural productivity. However, inefficient fertilizer use can significantly increase production costs, water pollution, and greenhouse gas emissions. To capture both the spatial heterogeneity and dynamic nature of this problem, we develop a multi-stage network production model, which links the sequential stages of crop growth within the overall crop production process. We use this framework to estimate nitrogen fertilizer application inefficiency and to determine the optimal rate and timing of fertilizer application. We apply this framework to wheat production at the field scale, using an agronomic simulation model calibrated to experimental data from Australia. Our results indicate that it is optimal to reduce the overall fertilizer application rate and to move away from the current practice of front-loading fertilizer in the initial stages of crop growth toward the intermediate stages. This can be achieved without compromising yields while also reducing nutrient losses.