A probabilistic analysis of cost-benefit among nitrogen fertilizer application, corn production and drinking water...

Nitrate is a drinking water contaminant regulated by the U.S. Environmental Protection Agency, with a maximum contaminant level of 10 mg L^-1 as nitrogen. In the U.S. Midwest, nitrate concentration in many drinking water sources exceeds that threshold due to non-point source pollution of nitrogen fertilizer loss from cropland, which is compounded by extensively installed tile drainage (subsurface drainage). To maintain compliance with the EPA drinking water standard, community water systems (CWSs) must utilize costly treatment methods to reduce nitrate concentrations in their source water. On the other hand, many studies show that reducing fertilizer use could be an effective way for water protection from nitrogen pollution. However, reducing fertilizer use could reduce crop yield and jeopardize farmers' benefit. Therefore, the overall objective of this study was to analyze tradeoffs between potential loss to farmer revenue and savings to CWSs for different fertilization scenarios. A Monte Carlo analysis was utilized to estimate changes to farmer revenue and nitrate loads associated with various nitrogen fertilizer rate scenarios. Two CWSs in the Midwest were chosen to estimate how changes to nitrogen fertilizer application rates would affect nitrate drinking water treatment costs. Farmer net revenue was not significantly increased by utilizing nitrogen fertilizer application rates above 150 kg of nitrogen per hectare. In contrast, drainage nitrate loads increased with increased nitrogen application rates, which led to disproportionately large impacts on the frequency of nitrate treatment at the CWSs. According to the results, applying between 100 and 150 kg of nitrogen per hectare for corn farming could significantly reduce nitrate-related water treatment expenses without noticeably impacting farmers' income in this region.