Using Sub-Field Profitability As a Driver for Improving Environmental Performance.

Cropping systems are typically managed using spatially uniform practices that allocate operational costs and nutrient resources equally to all areas of the field. Despite this style of management, sub-field variability of soils, topography, and other factors influencing the availability of water and nutrients results in crop production that varys spatially across fields. Consequently, fields often include significant areas where yield does not provide a positive economic return compared to the cost of planting and managing the land. Within these areas there is a direct link between the sub-optimal utilization of resources (i.e. losses) and environmental performance. This work introduces an economic approach to identify spatially-explicit sub-field areas where increased profitability and return on investment (ROI) can be used as an incentive to make alternative management decisions that promote environmental conservation and mitigate nutrient losses. The goal of the work is to demonstrate that average profitability of cropping systems can generally be increased by limiting or completely withholding the allocation of nitrogen and other management resources to areas of fields that are operating at or below economic break-even. Utilizing detailed management expenses and precision yield monitor data, the spatially-explicit sub-field profitability and ROI is calculated for a field in Butler County, Iowa. Nitrogen losses due to leaching and denitrification within the corn and soybean system are modeled using the Denitrification-Decomposition (DNDC) model and compared with the results of the economic analysis to estimate the potential nitrogen losses that can be mitigated by removing non-profitable areas from production.