Effect of Enriched Coconut Shell Biochar on Soil Properties and Soybean (Glycine max L.) Yield in Acidic Soils of Eastern Dry Zone of Karnataka, India

A two-season field study was conducted at ICAR-KVK, Hadonahalli, which is located in the Eastern Dry Zone of Karnataka, to evaluate the influence of phosphorus-solubilizing bacteria (PSB) and zinc-enriched coconut shell biochar on soil biological properties, nutrient bioavailability and soybean (Glycine max L.) yield in acidic soils. 13 treatments, including a control, package of practice and various combinations of PSB and zinc-enriched biochar were assessed in randomised complete block design at P=0.05 level of significance. The biochar was characterized for its physical properties, including bulk density (0.38 Mg m-3), water holding capacity (76.27%) and chemical properties including pH (9.52), electrical conductivity (1.12 dS m-1) and nutrient composition. Results indicated significant improvements in soil dehydrogenase activity, phosphatase activity and major nutrient bioavailability (N, P, K and Zn) in treatments receiving 100% NPK, PSB enriched FYM at 3.125 t ha-1 and different doses of zinc enriched Biochar at 5 t ha-1 compared to the control and package of practice. Soybean yield was maximized under treatments combining PSB-enriched FYM and zinc-enriched biochar, with the highest yield observed in T6 (23.61 q ha-1). The enhanced yield was attributed to improved soil health and nutrient dynamics by PSB and biochar. These findings underscore the potential of PSB and zinc-enriched biochar as sustainable amendments for enhancing soil fertility, crop productivity, and nutrient use efficiency in acidic soils.