Effects of fertilization on soil active organic carbon under Phyllostachys praecox stand

In this paper, fertilization experiment was conducted on Phyllostachys praecox stand to study the effects of different heavy application of chemical fertilizers and manure on soil active organic carbon pool. The results showed that compared with only applying chemical fertilizers, the combined application of chemical fertilizers and manure significantly increased the contents of soil total organic carbon (TOC), water-soluble organic carbon (WSOC), microbial biomass carbon (MBC) and mineralized carbon (MC) as well as the ratios of WSOC/TOC, MGC/TOC and MC/TOC (P < 0.01 or P < 0.05). With the decreasing application rate of manure, soil TOC, WSOC, MBC and MBC/TOC decreased significantly (P < 0.05), and when the application rate of manure was decreased by 50%, soil TOC, WSOC, MBC and MBC/TOC decreased by 10.75%, 12.02%, 30.94% and 22.61%, respectively. In the treatments of only applying chemical fertilizers, soil WSOC, MBC and MBC/TOC decreased obviously when the application rate of fertilizer nitrogen exceeded 1009.5 kg x hm(-2) x yr(-1). There were significant correlations between soil TOC, WSOC, MBC and MC (P < 0.01 or P < 0.05), among which, MBC and MBC/TOC could be used as the quality indications of soil carbon pool under Phyllostachys praecox stand.