2.6 Statistical analysis
All statistical analyses were performed by R software. Pearson correlation analysis was applied to explore relationships between SOC, DOC, and environmental factors, including pH, SWC, BW, nutrients, and microorganisms. Analysis of variance (ANOVA) isĀ used to compare differences among different treatments. Principle component and multiple linear regression analyses using the stepwise regression method were carried out to decipher potential links and predominant factors that affected SOC and DOC change. Considering environment factors were closely and intercorrelated, a partial least square path model (plspm) was used to explore and visualize effects of which ecological process or components on SOC and DOC before and after biochar amendment (Brown and Human, 1997). The plspm R package can be download at https://cran.r-project.org/src/contrib/Archive/plspm/.