Characterization of physiochemical properties and active microbial communities in the sugarcane (Saccharum officinarum L.) rhizosphere

Abstract

Soil quality index (SQI) is an important indicator that helps to evaluate soil fertility, optimize agricultural practices, and support long-term agricultural productivity. The aim of the study was to evaluate the SQI by characterizing the microbial and physicochemical properties of the sugarcane rhizosphere. A total of 20 composite soil samples were collected from 100 sampling points. The soil pH of the study area was slightly alkaline (ranging from 7.15 to 7.90). The soil texture ranged from clay loam to silty clay loam. Soil organic matter (SOM) was generally low, the amount being between 0.07% to 0.17%, which indicates a poor organic carbon level. The total number of bacteria varied from 1.31 × 107 to 2.54 × 107 CFU g-1 soil, with an average of 2.05 × 107 CFU g-1 soil. The active microbial communities, including nitrogen-fixing bacteria, phosphate-solubilizing bacteria, fungi, and actinomycetes, were found at a moderate level, even though the OM status was low. Soil samples were categorized into a moderate-quality group (SQI between 0.50 and 0.69), low-quality group (SQI <0.50) based on SQI value. The clay loam soil of sugarcane with onion cultivation showed a higher SQI value (0.630) compared to silty clay loam (0.297) soil of sugarcane with jute, indicating better nutrient levels and water-holding capacity. The study shows new insights into the physicochemical properties and active soil communities of the sugarcane rhizosphere, which indicate a better SQI value and suggest strategies for managing fertilizer, organic matter outputs, and ultimate soil health for sustainable sugarcane and other crop production.