Effects of maize straw on organic carbon pool in different organic carbon with different contents of organic carbon in black soil

Objective  To investigate the effects of different addition levels of maize straw on organic carbon pool of black soil with different organic carbon contents, and provide important references for improving the quality of degraded black soil and repairing with straw.

Method  Different amounts (0.5%, 1.5%, and 2.5%) of maize straw were added to black soils with two different organic carbon contents by outdoor culture method to study the content changes of total organic carbon (TOC), readily oxidizable organic carbon (ROC), microbial biomass carbon (MBC), dissolved organic carbon (DOC), particulate organic carbon (POC), light fraction organic carbon (LFOC), mineral-bound organic carbon (MOC), high fraction carbon soil (HFOC) and inert organic carbon (IOC), and correlations among each component of the soil.

Result  All three straw amounts applied increased the contents of TOC, ROC, MBC, DOC, POC, LFOC, MOC, and IOC in two black soils. The enhancing effects were more obvious on the soil with low organic carbon content than the soil with high organic carbon content. The HFOC contents of the two black soils decreased. All the components of soil organic carbon pool except LFOC and HFOC had highly significant positive correlations with TOC. Also the correlation relationships between ROC, MBC, DOC contents and POC content in each treatment were highly significant.

Conclusion  All three straw adding amounts have certain effects on the black soils with two kinds of organic carbon contents. The application of high straw adding amount can effectively enhance the carbon pool component contents of two soils, especially the soil with low organic carbon content. In the range of straw adding amount, the best treatment is mass ratio 2.5%.