Four years of free-air CO_2 enrichment enhance soil C concentrations in a Chinese wheat field

摘要

Elevated atmospheric CO_2 can influence soil C dynamics in agroecosystems. The effects of free-air CO_2 enrichment (FACE) and N fertilization on soil organic C (C_(org)), dissolved organic C (DOC), microbial biomass C (C_(mic)) and soil basal respiration (SBR) were investigated in a Chinese wheat field after expose to elevated CO_2 for four full years. The results indicated that elevated CO_2 has stimulative effects on soil C concentrations regardless of N fertilization. Following the elevated CO_2, the concentrations of C_(org) and SBR were increased at wheat jointing stage, and those of DOC and C_(mic) were enhanced obviously across the wheat jointing stage and the fallow period after wheat harvest. On the other hand, N fertilization did not significantly affect the content of soil C. Significant correlations were found among DOC, C_(mic), and SBR in this study.