Environmental Influence on the Dominance of Phosphate-Solubilizing Bacteria (Bacillus subtillis) and Mycorrhizal Fungi (Acaulospora spp. and Glomus spp.) on the former mining land of PT. SIG TUBAN

Abstract

Post-mining land generally experiences a decline in soil quality, which impacts microbial activity. This study aims to analyze the influence of environmental factors and soil physicochemical properties on the dominance of phosphate-solubilizing bacteria (Bacillus subtilis) and arbuscular mycorrhizal fungi (AMF) in the post-mining land of PT Semen Indonesia (SIG) Tuban. The study was conducted in three zones: Zone A (new excavation), Zone B (transition), and Zone C (revegetation). The parameters observed included environmental factors, soil physicochemical properties, Bacillus subtilis population, AMF spore count, and root colonization. Results showed that the highest Bacillus subtilis population was found in Zone B, at 5.2 × 10⁶ CFU/g of soil. In contrast, the highest AMF spores (360 spores/100 g of soil) with 68% root colonization were found in Zone C. Soil conditions with a pH of 7.0, 3.5% organic carbon, and 50% porosity were shown to support the development of these microorganisms. Therefore, revegetation combined with the addition of organic materials and the use of AMF and Bacillus subtilis is recommended to accelerate soil fertility restoration in post-mining land.