Deep placement of controlled-release and common urea achieves the win–win of enhancing maize productivity and decreasing environmental pollution

Abstract

The application of controlled-release urea or deep fertilization is effective for increasing crop yields. However, more research is needed to determine whether the deep placement of controlled-release and common urea can increase crop productivity and reduce environmental pollution. Between 2019 and 2021, we conducted field experiments in semi-humid and drought prone areas of the Loess Plateau region in China to study the effects of different controlled-release and common urea fertilization methods on maize productivity. Further experiments were conducted in semi-arid areas in 2022 and 2023 to verify the research results. We used the traditional fertilization strategy with common urea (TFC) as the control, deep placement of common urea (DFC), traditional fertilization with controlled-release and common urea (TFB), and deep placement with controlled-release and common urea (DFB) as optimized fertilizer management strategies. The results showed that the deep placement of controlled release and common urea changed the temporal and spatial distributions of the soil NO₃^–-N and NH₄⁺-N, which affected the N₂O and NH₃ emissions. The NH₃ emissions under DFC, TFB, and DFB were lower by 29.78 %, 32.77 %, and 59.08 % than TFC, and N₂O emissions were lower by 38.21 %, 40.96 %, and 72.89 %, respectively. Compared with TFC, the maize yields under DFC, TFB, and DFB were 7.91 %, 8.41 %, and 15.11 % higher, respectively, and the nitrogen use efficiencies were 14.23 %, 15.60 %, and 27.83 % higher, whereas the yield-scaled N₂O emissions were 38.21 %, 40.96 %, and 72.89 % lower, and the yield-scaled NH₃ emissions were 29.78 %, 32.77 %, and 59.08 % lower. Overall, DFB obtained the highest maize yield (12013.35 kg ha^–1) and nitrogen use efficiency (47.15 %), as well as the lowest gaseous nitrogen loss intensity (1.13 g N kg^–1 grain), global warming potential (323.08 kg CO₂-eq ha^–1), and greenhouse gas emission intensity (GHGI, 27.13 g CO₂-eq kg^–1 grain). Therefore, deep placement of controlled-release and common urea is an effective fertilizer management strategy that can balance maize productivity and environmental pollution in the Loess Plateau region of China.