It is unclear whether enhanced efficiency fertilizer (EEF) or deep fertilization strategies (DF) can simultaneously improve crop productivity and reduce gaseous nitrogen losses. The DF strategy’s investment cost is lower than that of EEF’s, with more potential for large-scale promotion. However, there is still a need for a comprehensive comparison and evaluation of DF and EEF’s effects on crop productivity and gaseous nitrogen losses. Here, we examine the effects of DF and EEF on crop yield, nitrogen use efficiency (NUE), and nitrous oxide (N₂O) and ammonia (NH₃) emissions by a meta-analysis of published studies. We collected peer-reviewed articles on EEF and DF published in recent decades and conducted a global meta-analysis, and explored their responses to different climatic, field management practices, and environmental factors. The results showed that compared with urea application on the surface, EEF and DF significantly increased yields by 7.52% and 13.88% and NUE by 25.84% and 36.27% and reduced N₂O emissions by 37.98% and 34.18% and NH₃ emissions by 42.37% and 69.68%, respectively. The DF strategy is superior to that of the EEF. Due to differences in climatic factors, soil properties, and management practices, the effects of DF and EEF in improving crop productivity and gaseous nitrogen loss vary. However, in most cases, DF is more beneficial than EEF. Compared with EEF, DF significantly increased the yield by 84.63% and reduced NH₃ volatilization by 64.47%, yield-scaled N₂O emission by 13.32%, and yield-scaled NH₃ emission by 60.23%. Therefore, we emphasize that DF can achieve higher yields, nitrogen fertilizer utilization efficiency, lower emissions of gaseous nitrogen, and lower yield-scaled N₂O and NH₃ emissions than EEF, which is beneficial for the sustainable development of global agricultural ecosystems. The research results provide valuable information on crop productivity and environmental costs under an effective fertilizer type and fertilization strategy management.

Deep fertilization is a beneficial approach for reducing nitrogen losses. However, the effects of various fertilization depths on maize (Zea mays L.) productivity and environmental footprints have not been thoroughly understood. Therefore, a field experiment was conducted to investigate the effects of different fertilization depths of 5 cm (D5), 15 cm (D15), 25 cm (D25), and 35 cm (D35) on maize productivity and environmental footprints. Reactive nitrogen (Nr) losses and greenhouse gas (GHG) emissions were assessed using life cycle analysis. We hypothesized that deep fertilization can obtain lower carbon and nitrogen footprint. The results indicated that deep fertilization decreased the N₂O and NH₃ emissions while increasing the CH₄ uptake. Compared with D5, D15 resulted in an increase in total GHG emissions and carbon footprint (CF), whereas D25 decreased by 13.0% and 23.6%, respectively. Compared with D5, the Nr losses under D15, D25, and D35 conditions was reduced by 11.3%, 17.3%, and 21.0%, respectively, and the nitrogen footprint (NF) was reduced by 16.0%, 27.4%, and 19.0%, respectively. The maize yield under D15 and D25 increased by 5.7% and 13.8%, respectively, compared with the D5 treatment, and the net economic benefits of the ecosystem increased by 7.1% and 17.1%, respectively. In summary, applying fertilizer at a depth of 25 cm can significantly reduce the environmental footprints and increase maize productivity, making it an effective fertilization strategy in the Loess Plateau region of China.

Winter wheat covers approximately 2.21 × 10⁸ ha globally, making it the most widely cultivated cereal crop in the world. In recent years, integrated water and fertilizer management has significantly improved winter wheat yield and nitrogen use efficiency; however, quantitative assessments of nitrogen cycling under different fertilizer forms in such high-yield systems remain limited. From 2022 to 2024, a two-year field experiment was conducted in drip-irrigated winter wheat fields in northern China. Four nitrogen fertilizer forms were applied: nitrate nitrogen fertilizer (NON), ammonium nitrogen fertilizer (NHN), amide nitrogen fertilizer (CON), and urea ammonium nitrate fertilizer (UAN), along with an unfertilized control (CK). Compared with NON, NHN, and CON, UAN reduced cumulative N₂O emissions by 10.40–15.64% and NH₃ volatilization by 2.04–9.33% (p < 0.05). It also increased the leaf area index and biomass accumulation at maturity, as well as grain yield (3.70–10.28%), nitrogen harvest index (4.58–12.88%), and nitrogen use efficiency (12.14–39.25%) (p < 0.05). Furthermore, UAN significantly decreased the net nitrogen surplus (24.18–45.70%) and nitrogen balance values (25.64–55.82%) (p < 0.05). Correlation analysis indicated that the reduction in nitrogen balance was primarily attributed to lower N₂O emissions and improved nitrogen use efficiency (p < 0.05). In conclusion, the application of urea ammonium nitrate under integrated water–fertilizer management achieved higher yield, greater efficiency, and environmentally sustainable production in drip-irrigated winter wheat systems in northern China.