Comprehensive increase in CO release by drying-rewetting cycles among Japanese forests and pastureland soils and exploring predictors of increasing magnitude

Suzuki, Yuri*; Hiradate, Shuntaro*; Koarashi, Jun   ; Atarashi-Andoh, Mariko  ; Yomogida, Takumi   ; Kanda, Yuki*; Nagano, Hirohiko*

The present study evaluated overall trends of the dry-wet cycle effect on carbon dioxide (CO) release and explored environmental and soil predictors for its effect size among ten Japanese forests and pastureland soils. In the 84-days incubation including three dry-wet cycles, CO release was 1.3 to 3.7-fold greater than that under the continuously constant moisture condition. This increasing magnitude of CO release by dry-wet cycles was found to correlate with pyrophosphate extractable aluminum content in soil. Whereas soil microbial biomass carbon was significantly lower in dry-wet cycle than in continuously constant moisture, there was no significant relationship between the microbial biomass decrease and the increasing magnitude of CO release. Thus, the present study showed that comprehensive increase in soil CO release by dry-wet cycles is regulated by organo-aluminum complexes which are vulnerable against dry-wet cycles.