Assessment of Microbial Counts and -Enzyme Activities in Coastal Saline Soils of Eastern India

Abstract

An investigation was carried out to study the effect of salinity on microbes and enzyme activities of the salt affected soils in five districts of Odisha, India adjacent to Bay of Bengal in relation to physico-chemical properties to suggest suitable strategies for sustainable crop production. The soils are strongly acidic to slightly alkaline, and having a salinity of 2.28 to 8.11 dS m^-1, low in organic C, available N and moderate amounts of available phosphorus and potassium. The microbial population was relatively lower in these saline soils and in which bacteria was dominant over fungi and actinomycetes. Soil biological activity in terms of dehydrogenase and fluorescein diacetate activities in the saline soils varied from 0.89-2.11 mg TPF hr^-1 g^-1 soil and 0.91 to 2.31 mg g^-1 hr^-1, respectively. Acid phosphatase activity was relatively higher (27.8 - 64.2 mg p-nitrophenol g^-1 soil h^-1) than alkaline phosphatase activity (17.8 - 55.9 mg p-nitrophenol g^-1 soil h^-1) thereby influencing the P transformations. Among the various soil groups, Vertisols had higher status of available nutrients and enzyme activities followed by Inceptisols, Alfisols and Entisols. Salinity had negative relationship with all the microbial variables and chemical properties of the soil, indicating that the increase in soluble salt content affects severely the bio-chemical transformations that regulate inherent soil fertility. Since majority of soil biochemical transformations are dependent on presence of microbes and microbial activities, the present investigation emphasized the intervention of suitable strategies for maintenance of soil quality to realize higher crop productivity in the coastal regions.