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

TLDR

Improving nitrogen management to boost agricultural output while minimizing environmental impacts is essential for sustainable food production amid climate change, and enhanced‑efficiency fertilizers (EEFs) have been developed to better match nitrogen release with crop uptake, potentially improving nitrogen use efficiency and reducing losses. The study aims to determine whether EEFs can significantly address the global nitrogen management challenge. A comprehensive analysis of worldwide studies from 1980 to 2016 evaluated four major EEF types—polymer‑coated fertilizers, nitrification inhibitors, urease inhibitors, and double inhibitors (combined urease and nitrification inhibitors)—for their effects on yield, nitrogen use efficiency, and nitrogen losses. Findings indicate that EEF effectiveness depends on type and cropping system, with double inhibitors in grassland and urease inhibitors in rice paddies delivering the greatest yield, NUE, and nitrogen‑loss reductions, while wheat and maize benefits are smaller; overall gains are maximized when nitrogen application is reduced from conventional rates and proper management practices are implemented.

Abstract

Improving nitrogen (N) management for greater agricultural output while minimizing unintended environmental consequences is critical in the endeavor of feeding the growing population sustainably amid climate change. Enhanced-efficiency fertilizers (EEFs) have been developed to better synchronize fertilizer N release with crop uptake, offering the potential for enhanced N use efficiency (NUE) and reduced losses. Can EEFs play a significant role in helping address the N management challenge? Here we present a comprehensive analysis of worldwide studies published in 1980-2016 evaluating four major types of EEFs (polymer-coated fertilizers PCF, nitrification inhibitors NI, urease inhibitors UI, and double inhibitors DI, i.e. urease and nitrification inhibitors combined) regarding their effectiveness in increasing yield and NUE and reducing N losses. Overall productivity and environmental efficacy depended on the combination of EEF type and cropping systems, further affected by biophysical conditions. Best scenarios include: (i) DI used in grassland (n = 133), averaging 11% yield increase, 33% NUE improvement, and 47% decrease in aggregated N loss (sum of NO3- , NH3 , and N2 O, totaling 84 kg N/ha); (ii) UI in rice-paddy systems (n = 100), with 9% yield increase, 29% NUE improvement, and 41% N-loss reduction (16 kg N/ha). EEF efficacies in wheat and maize systems were more complicated and generally less effective. In-depth analysis indicated that the potential benefits of EEFs might be best achieved when a need is created, for example, by downward adjusting N application from conventional rate. We conclude that EEFs can play a significant role in sustainable agricultural production but their prudent use requires firstly eliminating any fertilizer mismanagement plus the implementation of knowledge-based N management practices.