An economic assessment of nitrogen modeling tools in Delaware's Chesapeake Bay Watershed

Abstract

Nitrogen (N) management plays a central role in balancing agricultural productivity and environmental protection. This study evaluates how different N recommendation methods influence farm profitability and environmental outcomes for corn production in the Delaware portion of the Chesapeake Bay Watershed. Using the Cycles agroecosystem model, we simulate crop yield, nitrate (NO₃) leaching, and nitrous oxide (N₂O) emissions across multiple soils, years, and management systems to compare three approaches: a standard Extension rate, an Extension rate with a soybean credit, and an in-season N modeling tool. ☐ Economic outcomes were assessed by combining simulated yields with market-based fertilizer and crop prices, while environmental costs were estimated using established per-unit social cost values for NO₃ and N₂O, adjusted to current dollars. This framework allowed evaluation of private benefits (profit), public (social) costs, and net benefits across management scenarios. ☐ The results show that Conservation systems generally achieved higher profits and lower environmental costs than Conventional systems. Among recommendation methods, the soybean credit and N-modeling tool produced lower application rates closer to both private and social optima, while the standard Extension method often resulted in over-application. Sensitivity analyses on prices and precipitation confirmed that these patterns held across a range of realistic conditions. Overall, both the soybean credit and N modeling approaches improve upon the status quo Extension recommendation, though their relative advantages depend on management context and growing conditions. Additionally, broader adoption of Conservation management practices may offer greater overall improvements in profitability and environmental outcomes.