Effects of fertilizer reduction on yield and nitrogen utilization in maize-soybean intercropping system

To investigate the characteristics of nitrogen utilization in maize-soybean intercropping system under reduced fertilization, we conducted a spilt-plot experiment, with maize monoculture, soybean monoculture and maize-soybean intercropping as the main plot, and no fertilization, reduced fertilization (by 20%) and conventional fertilization as the sub-plot. We examined the effects of different cropping patterns and fertilization rates on crop nitrogen accumulation, nitrogen translocation, soil nitrogen content and yield. The results showed that nitrogen accumulation of intercropped maize and soybean under reduced fertilization was reduced at different growing stages. The total nitrogen accumulation in intercropping pattern was higher than the monoculture patterns, and nitrogen use efficiency was significantly increased by 13.6% and 129.1%, respectively. In the maize-soybean intercropping system, nitrogen accumulation of maize and soybean under reduced fertilization significantly increased by 5.8%-42.7% and 31.8%-35.4% at different growing stages except soybean at flowering stage, nitrogen translocation amount significantly increased by 114.8% and 40.7%, the nitrogen utilization efficiency significantly increased by 38.0% and 46.6%, the nitrate content in the 0-40 cm soil layer significantly increased by 4.5%-20.1% and 21.0%-52.7%, but without any significant changes in yield. The land equivalent ratio of intercropping pattern ranged from 1.14 to 1.50, which had yield advantage. In conclusion, reduced fertilization in maize-soybean intercropping system achieved efficient nitrogen utilization by enhancing accumulation and translocation of nitrogen and maintaining crop yield.