Enhanced-efficiency fertilizers are not a panacea for resolving the nitrogen problem.

Area of Science:

• Agricultural Science
• Environmental Science
• Soil Science

Background:

• Sustainable agriculture requires improved nitrogen (N) management to balance increased food production with environmental protection.
• Enhanced-efficiency fertilizers (EEFs) offer a potential solution by synchronizing N release with crop needs, thus improving N use efficiency (NUE) and reducing N losses.

Purpose of the Study:

• To comprehensively analyze the global effectiveness of four major EEF types: polymer-coated fertilizers (PCF), nitrification inhibitors (NI), urease inhibitors (UI), and double inhibitors (DI).
• To evaluate EEFs' impact on crop yield, NUE, and N losses across diverse cropping systems and biophysical conditions.

Main Methods:

• A meta-analysis of worldwide studies published between 1980 and 2016.
• Categorization of EEFs into PCF, NI, UI, and DI for comparative analysis.
• Assessment of yield, NUE, and aggregated N losses (nitrate, ammonia, N2O) under different agricultural systems.

Main Results:

• Double inhibitors (DI) in grasslands showed an average 11% yield increase, 33% NUE improvement, and 47% N loss reduction.
• Urease inhibitors (UI) in rice-paddy systems yielded a 9% increase in crop production, 29% NUE improvement, and 41% N loss reduction.
• EEF efficacy was highly dependent on the specific EEF type, cropping system, and environmental factors; performance in wheat and maize systems was more variable.

Conclusions:

• EEFs can significantly contribute to sustainable agricultural production by enhancing NUE and minimizing N losses.
• Optimal EEF benefits are realized when integrated with knowledge-based N management, including adjusting application rates and eliminating fertilizer mismanagement.
• Prudent and informed application of EEFs is crucial for maximizing their environmental and agricultural benefits.