Effects of intercropped leguminous green manure on maize nitrogen use of maize under different nitrogen fertilizations

【Objective】Excessive use of nitrogen fertilizers in maize production has led to environmental problems. Intercropping with leguminous green manure has been proposed as a sustainable agricultural practice that can improve soil nitrogen availability and crop nitrogen use efficiency. This study investigates the effect of intercropping leguminous green manure on nitrogen use of maize under different nitrogen application rates.【Method】A split-plot experimental design was used, with the main plots consisting of maize intercropped with common vetch (M||V) and sole maize cropping (SM). For cropping system, there were five nitrogen fertilizations: applying 360 (local practice, N360)), 270 (N270), 180 (N180) and 90 kg/hm2 (N90) of nitrogen fertilizer. No nitrogen fertilization was the control (N0). During the experiment, we measured soil nitrate and ammonium before sowing and at the harvest. We evaluated grain yield, nitrogen accumulation and allocation, nitrogen fertilizer use efficiency, and partial factor productivity to analyze the impact of intercropping with leguminous green manure on nitrogen use by the maize.【Result】Before sowing and at maize harvest, intercropping with leguminous green manure increased nitrate and ammonium concentrations in the 0-40 cm soil, with no significant difference between N270 and N360 in the intercropped maize belt. Compared with monocropped maize, intercropped with leguminous green manure increased dry matter accumulation, nitrogen accumulation and seed nitrogen allocation ratio by 5.8%, 9.1% and 6.2%, respectively. Dry matter and nitrogen accumulation of the intercropped maize in N270 and N360 were comparable. Intercropping significantly enhanced grain yield, nitrogen fertilizer utilization efficiency, and partial factor productivity after reducing nitrogen fertilization. Grain yield under M||V and N270 was not significantly different from that under M||V and N360 but was significantly higher than the monocropped maize in N360. Nitrogen utilization and partial productivity in M||V and N270 were significantly greater than those under both M||V and N360, and the monocropped maize in N360.【Conclusion】Intercropping leguminous green manure with maize with a 25% reduction in nitrogen fertilization improves nitrogen accumulation without compromising grain yield; it also improves nitrogen use efficiency and partial productivity.