"Properties of soil in Chiba University's Atagawa Farm [Shizuoka, Japan], 2: Soil organic matter and microbiological properties."

"The analysis of humic acid and microbiological characteristics of soils in Atagawa Subtropical Farm, Chiba University, was performed in 2000 by the five laboratories of Chiba University, Nihon University, Tokyo University of Agriculture and Technology and Meiji University. Soil samples were taken from the Site 2 and Site 4 of the Farm. Site 2 under evergreen broad leaf forest was located on the gentle slope, from a small ridge to valley, and soil materials were moved from the upper part of the site. The volcanic products at the Site 2 were affected by the upper horizons. The Site 4 consisted of volcanic products in the whole profile and utilized for the orchard (orange). Based on the humic acid analysis, such as the absorption curve of humic acid, D log K, RF and PQ, the humic acid from A horizon of the Site 2 and A1 horizon of the Site 4 were classified as B+ type (B type humic acid showing specific peaks of P type humic acid) and A type, respectively. Total number of microorganisms, biomass nitrogen content, respiration amount and qCO2 of the Site 4 sample were determined. Fungi in A horizon were highest, and they were lower in the deeper layers. Bacteria in Bwl and BC horizon were higher than in shallower layers. Biomass C and N showed the highest values in A1 horizon, and lowered but there was no tendency in deeper layers. The qCO2 in A2 horizon seemed relatively to be low. The factors influencing the activities of microorganisms in Site 4 were considered as following; 1) Site 4 was a part of slope. 2) Site 4 remained influence caused by the land-creation of this farm. 3) There was little water permeability in Bw horizon that was sticky. Both nitrate and ammonium were detected in deeper layers, not in A1 and A2, indicating that ammonium fixation by clay minerals takes places in subsurface layers."