Effect of application of lime with vermicompost on the activities of microorganisms of some acidic soils of West Bengal

Aim: To evaluate the efficacy of integrated application of lime at partial doses of lime requirement (LR) with vermicompost in acid soils to minimize the soil acidity, improve the population of beneficial microorganisms and their microbial activities in comparison to sole treatment of lime as per Lime Requirement dose. Methodology: Two highly acidic soils collected from the farmer’s field of South 24 Parganas district, West Bengal having no history of acidity management were used. The soils were treated with different rates of lime requirement (LR, ⅔LR & ½LR) and lime (½LR) + vermicompost (5 tha-1) treatments and incubated for 60 days. Soil pH, soil organic carbon content, different microbial populations, microbial respiration and enzymatic activities (FDHA and DHA) were assessed at different days. Results: The study indicated that the lime treatments showed rapid increase in soil pH towards the slightly alkaline condition whereas lime +vermicompost treatment (T5) successfully maintained the neutralized condition. Integrated treatment of lower doses of lime and vermicompost (T5) was found to efficiently promote the microbial population (rhizobium, phosphate and potassium solubilizing bacteria) and microbial respiration (basal and substrate induced respiration) activity, which might be attributed to the improvement soil microbial status. FDHA and DHA increased significantly with ‘lime’ as well as the ‘lime with vermicompost’ treatments in comparison to control. Interpretation: The incorporation of lower amount of lime and organic matter efficiently neutralizes the acidity and boosted up the microbial activities simultaneously that in turn might improve the soil health. The high cost to purchase the huge quantity of lime as recommended LR (9.25 tha-1) for studied soils turns the farmers uninterested to follow lime practice and interrupted the mitigation of soil acidity. Thus, the study might conclude that the integrated approach of lime application@½LR with vermicompost might successfully ameliorate the acid soils in terms of acidity as well as the soil microbial activities. Key words: Acid soil, BSR, Dehydrogenase, Fluorescein diacetate, SIR, Lime, Vermicompost