Meta-analysis of soil organic carbon fraction response to land uses

Improving soil carbon sequestration is important in the mitigation of the atmospheric greenhouse effect in the context of global climate change. The effects of different land uses on soil organic carbon fractions were explored by a meta-analysis. This analysis studied the characteristics of soil total organic carbon (TOC) and active organic carbon in the 0 – 100 cm soil layers under five different land uses: Forestland, orchard, natural grassland, artificial grassland, and cropland. In addition, the relationship between TOC and active organic carbon in soil was explored. Compared with cropland (control), both forestland and artificial grassland significantly increased the TOC content of 0 – 100 cm soil layers by 3.1% ~ 26.6% and 8.7% ~ 24.7%, respectively (P < 0.05). Natural grassland and orchard significantly increased the TOC content of 0 – 60 and 20 – 80 cm soil layers by 6.0% ~ 17.2% and 5.6% ~ 19.8%, respectively (P < 0.05). The response of the active organic carbon fraction to land use also differed significantly in different soil layers. Particulate organic carbon (POC) and microbial biomass carbon (MBC) displayed similar trends to TOC in the 0 – 100 cm soil layers, while easily oxidizable carbon (EOC) and dissolved organic carbon (DOC) were slightly different. Both forestland and orchard significantly increased EOC content in the 0 – 80 cm soil (P < 0.05), while there was no significant effect of the EOC content in the 80 – 100 cm soil layer (P > 0.05). Natural grassland and artificial grassland increased EOC content significantly in the 0 – 100 cm soil layers (P < 0.05). DOC content was affected by orchard and natural grassland, and was significantly higher than cropland in the 0 – 80 cm (P < 0.05). DOC content of forestland and artificial grassland was significantly higher than cropland in the 0 – 60 cm soil layers (P < 0.05). There were highly significant positive correlations between TOC and EOC, POC, and MBC (P < 0.01), and no significant correlations with DOC (P > 0.05). Overall, the effect values of soil organic carbon components in different soil depths were heterogeneous due to land uses. Among these uses, forestland and artificial grassland displayed better soil fertility and soil quality maintenance functions. The data provide a theoretical reference for management of soil carbon fraction under different land uses.