Trade-offs between agronomic and environmental benefits: A comparison of inhibitors with controlled release fertilizers in global maize systems

Abstract

The application of enhanced efficiency fertilizers (EEFs) is widely considered as an effective approach to decrease reactive nitrogen (Nr) losses and improve crop yield. Although the effectiveness of EEFs is influenced by soil properties and management practices, the main drivers on global maize ( Zea mays L.) systems are still unclear. The aims of this study were to: (i) determine the effectiveness of EEFs on maize productivity, nitrous oxide (N 2 O) emissions, ammonia (NH 3 ) volatilization, and nitrate (NO 3 - ) leaching; (ii) explore the EEFs efficacy under different management and environmental factors; and (iii) estimate the economic and environmental costs of the maize production system under different fertilization treatments. The responses of maize productivity and Nr losses to EEFs were determined based on the data from 191 studies (1039 pairs of observations) worldwide using meta-analysis. Five types of EEFs include nitrification inhibitor (NI), urease inhibitor (UI), double inhibitors (NIUI), controlled release urea (CRU), and controlled release bulk blending fertilizer (CRBF). The major drivers regulating EEFs efficacy were analyzed by random forest analysis. The EEFs significantly increased maize grain yield, N uptake, and N use efficiency (NUE) by 8.5 %, 11.6 % and 35.8 % compared to urea alone, respectively. The UI was most effective at increasing maize yield (by 11.0 %) and CRU was most effective at improving NUE (by 43.2 %). The UI decreased NH 3 volatilization by 46.0 % across all EEFs, whereas NI and NIUI were most effective at reducing N 2 O emissions (by 45.9 %) and NO 3 - leaching (by 45.3 %), respectively. The effects of EEFs on maize yields and Nr losses were most dependent on soil pH, soil organic carbon (SOC) content, soil texture, and annual precipitation. Inhibitors performed better when they were incorporated, and the suitable fertilizer placement for CRU and CRBF were banded. Lower total economic and environmental costs occurred when applying EEFs relative to urea alone, which was attributed to the environmental benefits. Inhibitors and CRU reduced urea usage while maintaining maize yields relative to urea alone, and inhibitors decreased environmental costs over CRU, especially UI and NIUI. The yield-increasing effects were more significant when inhibitors were applied in neutral or alkaline soils, while CRU was more effective in soils with low total N. The EEFs should be used with appropriate management practices targeting different environmental conditions to strike a balance between pollution reduction and crop productivity improvement. • A global meta-analysis assessed the agronomic and environmental benefits of enhanced efficiency fertilizers (EEFs). • Urease inhibitor addition maximized maize yield (11.0 %) and reduced ammonia volatilization (46.0 %). • Nitrification inhibitors and double inhibitors minimized N 2 O emissions by 45.9 % and NO 3 - leaching by 45.3 %, respectively. • Soil pH and soil organic carbon content were the critical factors influencing the response of maize yield to EEFs. • EEFs increased net economic-environmental benefits by 32.93–188.85 $ ha −1 compared to urea alone.