The application of organic matter has received increasing attention in many countries in recent decades. Laboratory and pot culture experiments were carried out to assess the impact of various organic carbon sources during and after decomposition on the micronutrients (Fe, Cu, Mn, and Zn) availability. Appropriate amounts of FYM, City Compost, Pongamia and Glyricidia litter (at rate of one percent C) were incubated with three soils (Vertisol, Alfisol, and Entisol ).At periodic intervals , destructive sampling was done for analyzing various chemical properties at 5,10,15,30,60, and 90 days after incubation . A pot culture experiment was conducted to study growth response of maize plant, yield and uptake of micronutrients with respect to various organic materials at rate of one percent C. The incorporation of various organic materials indicates a significant increase in the organic carbon content due to treatment. There were significant differences in the available Fe, Cu, Mn, and Zn content of the soil. The higher availability of Fe, Cu, Mn, and Zn nutrients in the soil due to application of manures was ascribed to mineralization of the manure, reduction of fixation and complexing properties of these manures with micronutrients. After registering peak Fe and Mn availability, the Fe and Mn contents decreased in the second half of incubation experiment. However, such decrease in available Cu and Zn content was not recorded during the same period. Significant differences were observed in dry matter production of maize at 60 DAS due to treatments. Addition of FYM at one per cent C recorded the highest dry matter yield, followed by Glyricidia litter and the lowest was in RDF. Keywords: organic manures, Fe, Cu, Mn,Zn