Risk-benefit ranking of nitrification and urease inhibitors applied to agricultural soils using the PROMETHEE method

Nitrification and urease inhibitors (NUIs) are chemical compounds that can reduce nitrogen loss and potentially enhance fertilizer nitrogen use efficiency when combined appropriately with nitrogen fertilizers. Many studies have highlighted their agricultural and environmental benefits, including improving crop yields, reducing nitrate leaching, and lowering nitrous oxide emissions. However, their unintended presence in the environment (e.g., surface water) and the food chain has raised concerns. Individual inhibitors exhibit different levels of risks and benefits that need to be evaluated separately. In this study, a risk-benefit ranking was conducted to prioritize 10 NUIs based on environmental exposure, toxicity, and benefit through the preference ranking organization method for enrichment evaluation. In general, the urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) was identified as the most preferred, with a net flow value (φ) of 0.11 in the risk-benefit ranking of all NUIs, due to its significant agricultural and environmental benefits with low risk from its short half-life. This assessment was supported by the fact that nitrification inhibitors can sometimes increase ammonia emissions, reducing their overall effectiveness in improving nitrogen use efficiency as compared with urease inhibitors. Our results also illustrated that the nitrification inhibitor dicyandiamide (DCD) was a recommended alternative (φ = 0.08) among the evaluated nitrification inhibitors. This study assists stakeholders to balance the benefits and potential risks regarding the environment and human health issues associated with the application of NUIs in agriculture.