Effect of fertilizer and manure application on microbial numbers, biomass, and enzyme activities in volcanic ash soils

Abstract

Abstract Fertilizer and manure application affected the microbial numbers and biomass in topsoil and subsoil fields consisting of volcanic ash upland soil. 1. Microbial numbers (bacteria, spore-forming bacteria, actinomycetes, and fungi) were the largest in the farmyard manure plot, followed by the chemical fertilizer plot, and smallest in the no-fertilizer plot in both fields. The numbers of all the microorganisms except fungi in the samples from the topsoil field were larger than in the samples from the subsoil field in the respective plots. Microbial numbers obtained here were several times as large as the mean values of microorganisms in volcanic ash upland soils, presumably due to the use of a Waring blender for dispersing the soil samples. 2. Soil microbial biomass carbon was the largest in the farmyard manure plot, followed by the chemical fertilizer plot, and smallest in the no fertilizer plot in both fields. Microbial biomass carbon in the samples from the subsoil field was larger than that in th...