Abstract
Soil microbial biomass and microbial respiratory activity were investigated in organic matter, such as leaves and stems of crotalaria, cattle manure compost and bark compost. The type of organic matter strongly influenced the soil microbial characteristics. While the microbial biomass increased with the application of organic matter, the degree of increase differed according to the variety of organic matter. The microbial biomass increased in the plots in the following order: leaves of crotalaria > stems of crotalaria > cattle manure compost, but it did not increase with the application of bark compost. It reached 1700 mg C kg^<-1> dry-soil in the plot containing leaves of crotalaria one day after application. Microbial respiratory activity increased with the application of crotalaria leaves and stems but not with that of cattle manure compost and bark compost. The respiratory activity decreased gradually in each plot to a similar level to that of the no-organic-matter-added plot after 15 days. Organic matter used in this study was classified into three types: one that increases only the biomass, one that increases both the biomass and respiratory activity, and one that increases neither.
