Variability in Soil Physicochemical Properties and Microbial Population in an Indian Subtropical Forest

Abstract

Aim: The below ground biota in forest ecosystems determine and regulate the availability of nutrients in soil and is likely to indicate variation in population and metabolism with respect to the soil quality. Therefore, the present study was undertaken to study the physico-chemical characteristics, bacterial-fungal population and soil respiration in different land use zones of a sub tropical Indian forest. Methodology: Soil samples were collected from 0-20 cm depth using a core sampler (5 cm diameter) and from 12 sub plots and three regions for physicochemical and microbiological studies. For measurement of soil respiration 20 cm x 20 cm soil blocks were cut from the sub plots. Sampling was done three times in a month for two months in natural sal (Shorea robusta) forest, bamboo plantation and wet land of the Chandaka-Dampara wild life sanctuary, India in the dry season (March-April). The samples were carried to the laboratory for experimental purpose. Results: In the soil, the sand percentage varied from 81.4% (Wet land) to 89.2% (Sal forest), clay 7.5% (Sal forest) to 15% (Wet land) and silt 3.3% (Sal forest) to 3.6% (Wet land) in different sampling zones. Wet land soil indicated the highest pH (8.21) and sal forest the lowest (5.54). Percent organic carbon (OC) was the highest (0.33%) in soil from bamboo plantation and lowest (0.11%) in wet land. The highest bacterial population (9.3 x 104 CFU / g soil) was observed in bamboo plantation and fungal population (8.0 x 104CFU/g soil) in sal forest. Soil respiration ranged from 475 mg/hr/m² in sal forest to 570 mg/hr/m² in bamboo plantation. A significant positive correlation of %OC with bacterial population and soil respiration was observed. Conclusion: It was evident from the study that soil from bamboo plantation with highest percent organic carbon, organic matter and moderately acidic pH provided the most suitable condition for maximal bacterial growth and soil respiration relative to other sampling zones. Seasonal variation in the soil microbial population and metabolism with respect to soil nutrient dynamics needs further investigation.