Soil Physical Indicators under Bean Cultivation with Biological Treatments

Abstract Biological products, including entomopathogenic fungi, are widely applied in agriculture to control pests and enhance crop productivity and quality. While their biological effects are well-documented, few studies focus specifically on their influence on soil physical quality indicators. This study addresses that gap by evaluating the effects of selected biological products, applied to common bean (Phaseolus vulgaris L.), exclusively on the physical properties of soil. The field trials were conducted over two years on two soil types: Fluvisol (Negovan, Sofia Region) and Luvic Chernozem (Ruse Region). Seven treatment variants were tested, including a control, individual and combined applications of the bioproducts Naturalis (N) and SoftGuard (SG), and three active strains (B339, B538, B730) of Beauveria bassiana. Results showed that different treatments had varying effects depending on soil type. On Fluvisol, B338 had the most beneficial effect, while B730 and B339 were most effective on Luvic Chernozem. Bioproducts reduced soil compaction but had no significant effect on plant-available water capacity (PAWC). This study contributes important insights into how biopreparations influence only the physical condition of soils, with implications for sustainable soil management in legume cultivation.