Abstract
Increasing nutrient use efficiency and decreasing labor requirements for rice production are high priorities across Asia. Fertilizer placement beside the rice plants at 50–100 mm depth (called side-deep fertilization, SDF) is a promising alternative to the traditional fertilization that can reduce the amount of chemical fertilizer required, improve the use efficiency of fertilizer, alleviate the shortage of labor force, and realize the clean and simple production of rice. However, the potential for increased productivity and the factors influencing SDF are unclear. In this study, we synthesized 85 studies in China to evaluate the effects of SDF on rice yield, rice quality, nutrient use efficiency combined with greenhouse gas emissions, and explored the effects of different soil environments and fertilization management measures on them. SDF increased rice yield by 4.8 %, nitrogen use efficiency (NUE) by 21.4 %, and reduced CH4 emission by 12.8 %, NH3 volatilization by 42.0 %, but had no significant effect on N2O emission. Random forest analysis showed that soil condition (pH, total nitrogen, available nitrogen and available phosphorus) and specific fertilization practices (amount and depth) were the most important factors on determining the effects of SDF. When the N application rate was ≤ 150 kg ha−1, the yield (9.2 %) and NUE (20.6 %) increases were largest. When the P application rate was ≤ 60 kg ha−1, SDF of P had the largest increase in rice yield (7.4 %) and partial factor productivity of phosphorus PFPP (7.2 %). Overall, when fertilizer placement was > 100 mm, and the soil nutrient content was low, SDF had a greater impact on rice yield and nutrient use efficiency. In conclusion, SDF increases rice yield with lower environmental cost and lower fertilizer rate which is valuable for food security and sustainable production.