Dynamics of the soil microbial biomass in the outer and inner part of aggregates following substrate incorporation
1995
Yamaguchi, T. (Tokyo Univ. of Agriculture and Technology, Fuchu (Japan). Faculty of Agriculture) | Hamada, R. | Sakagami, K. | Tanaka, H.
We devised a method to determine the soil microbial biomass in the outer and inner part of aggregates. Dynamics of the outer and inner part biomass of aggregates following substrate incorporation were measured by the above mentioned method and we discussed the relationship among the inner, outer and whole biomass. To clarify the influence of aggregates on the biomass, we used Andosol and Sand-dune Regosol. Andosol contained many aggregates and Sand-dune Regosol had none. 1) The fractionation of the biomass in the outer and inner part of aggregates followed the washing-sonication method. Each suspension was determined for the content of ninhydrin-reactive nitrogen after direct extraction by toluene. 2) The fluctuation pattern of the biomass after substrate incorporation differed between the outer and inner part biomass of aggregates, especially in Andosol. The biomass of the inner part of aggregates did not decline soon after a drastic increase in the biomass after substrate incorporation like other fractions, and this is why the whole biomass of Andosol declined slowly, reaching a steady state due to substrate input. 3) At the beginning, when the whole biomass became stable after substrate incorporation, it was an apparent stable time, because the fluctuation of the outer part biomass of aggregates was offset by the fluctuation of the inner part biomass of aggregates
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