CHANGES IN SOIL MICROBIAL ATTRIBUTES WITH SOIL CHARACTERISTICS AND PARENT MATERIALS

Healthy soils are essential to sustain crop production for a good quality of life. Soil microbial biomass is an important indicator of soil health and is highly sensitive to management practices and soil conditions. This study was aimed to determine the relationship of different microbial attributes such as biomass-C (MB-C) and -N (MB-N), mineralizable-C (min-C) and –N (min-N), microbial population and activity (CO2 evolution) with important soil characteristics (soil organic matter, total N, lime, pH, EC, particle size) in selected soil series developed under different parent materials. For this purpose, surface (0-10 cm) soil samples were collected from 9 different agriculturally important soil series in North Western region of Pakistan and analyzed for the required parameters. The results showed that most of the soil microbial attributes such as MB-C, MB-N, CO2 evolution, min-C, min-N and microbial population (bacterial and fungal) were generally greater in soils of loess deposits and lowest in soils of Swat alluvium. However, considerable variations in microbial attributes were observed among soils developed from same parent materials. The soil organic matter (SOM) and total N were generally greater in soils of loess deposits. However, EC, pH and lime contents were greater in soils of Kabul alluvium and lowest in Swat alluvium. Correlation analysis of the data revealed that MB-C, MB-N, min-C, min-N and CO2 evolution were positively correlated with SOM, total soil N, bacterial and fungal population. They were negatively correlated mostly with EC and clay content and to a lesser degree with lime content. These results suggested that soil microbial characteristics changes largely with the nature of soil characteristics within same parent materials.