ORGANIC MATTER-MICROBIAL BIOMASS RELATIONSHIPS IN FIELD EXPERIMENTS UNDER TROPICAL CONDITIONS - EFFECTS OF INORGANIC FERTILIZATION AND ORGANIC AMENDMENTS

The analysis of continuous fertilizer and manurial experiments in tropical conditions of India have shown that soil microbial biomass C and N increased with balanced fertilization. The additions of organic amendments increased microbial biomass even when the organic C content of the soil did not increase. The increase in microbial biomass was attributed to better plant growth resulting in higher rbizodeposition. The crop yields and N uptake were higher with the addition of farm yard manure or Sesbania green manure.