Abstract

The aim of this study was to substantiate the effectiveness of using biopreparations to increase the productivity of sweet clover, Sudan grass, and their mixture, improve forage quality, and restore soil fertility under the arid climate conditions of the Kazakhstan Aral Sea region, as well as to determine their impact on key agroecosystem processes. This research examined the effects of the biopreparations “Fitobacirin”, “Plantobacirin”, and “Azotobacterin” on growth characteristics, yield, forage quality, and soil condition in sweet clover, Sudan grass, and their mixture. The experiment comprised four treatments: a control (without biopreparation treatment) and three experimental treatments with the application of biopreparations. Indicators assessed included plant height, crop productivity, protein content, fibre, mobile phosphorus and potassium levels, as well as soil microbial activity. The results showed that biopreparation treatments significantly enhanced crop growth and productivity. The greatest yield increase was observed with “Plantobacirin”, which also led to a marked improvement in plant phosphorus nutrition. Biopreparations further increased protein content and metabolisable energy in the forage while reducing fibre content, indicating improved nutritional quality. The mixture of sweet clover and Sudan grass demonstrated a synergistic effect, resulting in higher productivity and enhanced forage quality compared to monocultures. Additionally, soil condition improved following the application of biopreparations: levels of organic matter, mobile phosphorus, and potassium increased, and biological soil activity was stimulated, as evidenced by higher dehydrogenase activity. This suggests restoration of soil fertility and activation of biological processes. The findings of this study confirm the effectiveness of biopreparations in boosting yields, improving forage quality, and enhancing soil health in arid environments. The results may be applied in the development of sustainable agricultural technologies aimed at increasing productivity and restoring agroecosystems in the Aral Sea region of Kazakhstan.