Author : Detera, Narses S.

Summary : Microrganisms are responsible for the biogeochemical transformations occuring in the soil. These microorganisms constitute the soil microbial biomass and can be used as index to assess sustainable land use. Few scientists have studied the soil biomass carbon and nitrogen using Philippine soils. Hence, this study was done mainly to examine the use of methods other than the chloroform technique for the determination of the biomass carbon and nitrogen. This study sigcifically aimed to: (1) determine the microbial population and some soil enzymatic activity of different soils; (2) compare the different methods of determining biomass C and N of soils under different soil management practices and (3) relate some chemical and physical properties of soils with either microbial population or some soil enzymatic activity. In order to attain the objectives mentioned, the physical, chemical and microbiological properties of soils studied were analyzed. The microbial population were counted using the agar plate method. The nitrifiers were enumerated using the Most Probable Number method. The soil enzymatic activities measured were urease, phosphomonoesterases and dehydrogenase activity.