Combined legume-based sowing systems and microbial biopreparations for restoring degraded chernozem fertility in the Southern Steppe of Ukraine

Abstract Introduction : Soil degradation in the Southern Steppe of Ukraine requires effective biological approaches to restoring chernozem fertility. Methods : This study evaluated the combined use of legume crops, mixed sowings and microbial biopreparations during a 3-year field experiment conducted in 2022–2024. Agrochemical, microbiological and statistical methods were used to assess changes in soil properties and crop productivity. Results : The integrated B5 treatment, combining mixed sowings with Azotokhelp, Helprost Universal, Phytocid and Organic-Balance, produced the strongest response. Humus content increased by 31%, readily available nitrogen by 40%, and the total number of soil microorganisms by 3.2 times. Nitrogen-fixing bacteria increased by 6.4 times, while dehydrogenase activity increased by 4.1 times. These improvements were accompanied by higher crop productivity: soybean yield increased by 75%, chickpea by 64% and lucerne green mass yield by 59%. Protein content and other yield-quality indicators also improved. Conclusion : The findings indicate that integrated legume-based biological management can enhance soil fertility, microbial activity and crop productivity. This approach may support regenerative agriculture and the restoration of degraded agroecosystems, although its long-term stability and economic feasibility require further evaluation.