Estimation of microbial biomass based on water-extractable organic matter from air-dried soils from Japanese forests and pasture

風乾土から水抽出された有機物による土壌微生物バイオマスの推定; 日本の森林および草地土壌を使った検討

永野 博彦*; 神田 裕貴*; 鈴木 優里*; 平舘 俊太郎*; 小嵐 淳   ; 安藤 麻里子  ; Guo, Z.*

Nagano, Hirohiko*; Kanda, Yuki*; Suzuki, Yuri*; Hiradate, Shuntaro*; Koarashi, Jun; Atarashi-Andoh, Mariko; Guo, Z.*

Water-extractable organic matter (WEOM) obtained from air-dried soil samples can be used to estimate microbial biomass instead of chloroform fumigation extraction (CFE) using fresh, moist soils and toxic solvents. However, the accuracy of such WEOM-based estimates has not been evaluated. We evaluated relationships between WEOM measurements obtained from air-dried soils and microbial biomass measurements obtained through CFE based on 50 soil samples from each of 10 soil profiles in Japanese forests and pasture. The amount of water-extractable organic carbon (C) obtained from air-dried soils corresponded to 31% of microbial biomass C, demonstrating a strong correlation. This result supports our hypothesis that WEOM represents a quantitative alternative to microbial biomass, particularly for C, offering a solution to the practical difficulties involved in measuring microbial biomass using CFE.