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

Abstract

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.