MACRONUTRIENT AVAILABILITY AND MICROBIAL POPULATION IN FLY ASH AMENDED ALLUVIAL SOILK. Theresa and J. Vimalin Hena
Investigation into the effect of fly ash with three organic manures viz., farm yard manure (FYM), green leaf manures (GLM) and humic acid (HA) and inorganic fertilizers on macronutrient availability and microbial population was studied. Rice (ADT 49) was selected to raise field study. Fly ash generated from Mettur Thermal Power Station was selected for the study and examined for its physical and chemical properties. Analysis of fly ash revealed that it is neutral to alkaline (pH 8.1) in reaction. The results confirmed that fly ash contains all the essential elements required for the plant growth as that of soil except organic carbon and nitrogen. It was observed that fly ash (@ 20 t ha-1 + GLM (@ 6.25 t ha-1 with RDF (150:50:50) increased the NPK availability in soil. Application of fly ash @ 20 t ha-1 + GLM @ 6.25 t ha-1+ RDF recorded the highest soil available N (183 kg ha-1), P (25.6 kg ha-1), K (313 kg ha-1). The treatment which received fly ash + GLM with RDF (150:50:50) recorded the highest grain (5.49 t ha-1) and straw yield (6.59 t ha-1). Combining GLM and FYM with fly ash influenced more microbial populations than fly ash alone. Fly ash application did not influence the population of fungi and actinobacteria while bacterial population showed a marked level of increase. Thus the integrated effect of fly ash, manures and fertilizer was well pronounced in enhancing the macronutrient availability, microbial population and rice productivity.