Sustainable management of water, nitrogen and biochar resources for soybean growth considering economic, environmental and resource use efficiency aspects: An integrated modeling approach

Abstract

Intensive soybean production requires that water and fertilizer are collaboratively managed in an accurate and efficient manner, while biochar application offers a sustainable approach for protecting land, alleviating water scarcity, and increasing crop yield. The purpose of this study was to carry out a multifactor coupling orthogonal experiment of irrigation, nitrogen and biochar in the soybean growing season in 2021 and 2022 via plot treatment, linking the effect of irrigation and nitrogen on soybean yield with the carbon sequestration and emission reduction properties of biochar. A dynamic regulation model with multi-dimensional objective synergy for soybean yield, water footprint (WF), carbon footprint (CFP), water use efficiency (WUE) and partial productivity of nitrogen fertilizer (PFPN) based on the comprehensive regulation framework of experimental-simulation-optimization was constructed. This model was used to explore the optimal irrigation, nitrogen and biochar application patterns and their synergistic effects on yield and environmental benefits. The results showed that soybean yield and PFPN were affected by irrigation, nitrogen application affected WF and WUE, and biochar application affected CFP. Irrigation significantly affected the soil water content and consequently the WF while enhancing the crop yield and PFPN. Compared to the I1 treatment, the I0 treatment reduced water consumption, and the addition of nitrogen (N0 and N1) contributed to higher crop yields and WUE. The addition of biochar significantly increased crop yield, WUE and PFPN while mitigating the impact of nitrogen fertilizer application on greenhouse gas emissions. Based on the three-factor interaction, the yield, WF, CFP, WUE, and PFPN in 2022 increased by 3.03%, 3.51%, 2.17%, 1.59%, and 7.61%, respectively, compared to those in 2021. In addition, combined with water and nitrogen application, biochar application reduced CFP while increasing soybean yield, WUE and PFPN. A multiobjective optimization model demonstrated that when the amounts of irrigation, nitrogen, and biochar in 2021 and 2022 were 178.4 mm, 104.6 kg/hm2, and 8650.8 kg/hm2 and 153.7 mm, 93.7 kg/hm2, and 8063.4 kg/hm2, respectively, the synthetic degrees of yield, WF, CFP, WUE, and PFPN reached 0.866 and 0.872, respectively. The coordinated regulation of irrigation, nitrogen, and biochar reached a high-quality coordinated level that was 14.39% and 7.13% higher in 2021 and 2022 than the best I0N0B1 treatment, respectively. In this study, a combination of experiment-simulation-optimization is used to propose optimal irrigation, nitrogen and biochar regulation methods that synergize soybean yield, resource use efficiency and environmental benefits, which are of theoretical value for promoting green and efficient soybean production in black soil areas.