Optimizing Biochar Application and Fertilization for Maize-soybean Intercropping System Based on Their Yields and Water-nitrogen Use Efficiency

Abstract

【Objective】 Intercropping is a sustainable cultivation practice for improving crop productivity and enhancing resource use efficiency. In this paper, we investigate the combined impact of nitrogen fertilization and biochar amendment on yields and water use efficiency of maize-soybean intercropping system. 【Method】 The experiment was conducted in plots. It consisted of three biochar treatments: 0 t/hm2 (C0), 15 t/hm2 (C1), and 30 t/hm2 (C2), and three nitrogen fertilizations: 135 kg/hm2 (N1), 180 kg/hm2 (N2), and 225 kg/hm2 (N3). No fertilization and biochar amendment were taken as the control (CK). Yield and water and nitrogen utilization efficiency were measured in each treatment. The TOPSIS method combined with the game theory was used to determine the optimal biochar and nitrogen applications for maximizing crop yields and water and nitrogen utilization efficiency of the intercropping system. 【Result】 Biochar and nitrogen applications significantly influenced yields and water and nitrogen utilization efficiency of the two crops. Biochar amendment had greater impact on corn yield and water and nitrogen utilization efficiency, while nitrogen application impacted the yield of soybean more. The C1+N2 treatment gave the highest maize yield and water utilization efficiency, while C1+N1 led to the highest soybean yield, nitrogen utilization efficiency, and nitrogen partial productivity. Results obtained from the carbon-nitrogen regulation model indicated that the comprehensive evaluation value of the synergistic effect of the carbon and nitrogen applications initially increased and then decreased with the increase in biochar and nitrogen applications. We also found that rationally reducing nitrogen application coupled with a biochar amendment had a positive effect on yields and water and nitrogen utilization efficiency of the intercropping system. 【Conclusion】 For the regions in northwestern China we studied, which have relatively sufficient water and fertilizers, amending the soil by 17.1~24 kg/hm2 of biochar combined with 154.8~173.7 kg/hm2 of nitrogen fertilization is optimal for yields and water and nitrogen utilization of corn-soybean intercropping system.

Keywords

• maize/soybean intercropping
• biochar
• reducing nitrogen application
• yield
• water-nitrogen use efficiency