Effects of Synergistic Application of Maize Straw and Biochar on Improvement of Saline-Alkali Farmland in the Yellow River Delta

Wang Jie; Shan Yan; Ma Lan; Song Yanjing; Wang Xiangyu

doi:10.14083/j.issn.1001-4942.2026.01.013

Abstract：Taking the coastal saline-alkali soil in the Yellow River Delta as the object,this study was conducted to investigate the effects of direct returning and returning after carbonization of straw on soil aggre-gates and saline-alkali farmland improvement,as well as to explore the reasonable addition ratio of the straw and biochar,in order to provide the scientific basis for practical promotion of maize strawing returning method in this area.Seven treatments were set including CF(conventional fertilization),T1(100%straw),T2(75%straw+25%straw biochar),T3(50%straw+50%straw biochar),T4(25%straw+75%straw bio-char),T5(100%straw biochar)and CK(blank control),with 25%reduction in chemical fertilizer applica-tion for T1 to T5.The effects of different returning methods on soil physical and chemical properties were ana-lyzed,as well as the distribution of aggregates with different particle sizes,stability,and contribution rate of organic carbon.The results showed that different field returning methods didn't change the physical and chemi-cal properties obviously,but increased the nutrient content of the saline-alkali soil.Overall,the proportion of microaggregate(<0.25 mm)particles in the soil was slightly lower than that of large aggregates(>0.25 mm),which were 36.54%to 53.98%and 46.02%to 63.47%of the total soil weight,respectively.The proportion of coarse aggregates(>2 mm)generally decreased with the decrease of straw proportion in the mixed materials,while the proportion of microaggregates increased with the decrease of straw.The mean weight diamenter(MWD)and geometric mean diameter(GMD)decreased with the decrease of straw proportion,and they were the highest under T1 treatment showing the strongest stability of aggregates.The organic carbon contribution rate of macroaggregates(>0.25 mm)and microaggregates(<0.25 mm)ranged from 49.18%to 65.98%and 27.91%to 41.88%,respectively.The application of fertilizers was reduced by 25%in T1 and T2 treatments,but their maize yield were not significantly different from that of CF.In summary,maize straw and biochar re-turning could effectively improve the quality of saline-alkali soil by increasing the content of soil organic mat-ter,nitrogen and phosphorus,promote the formation of large aggregates,and improved the stability of soil ag-gregates.However,as the proportion of straw returning decreased the MWD and GMD of soil aggregates and the organic carbon contribution rate of large aggregates decreased,while the organic carbon contribution rate of microaggregate showed an increasing trend.