Fig. 5
The structural equation model was used to evaluate direct and indirect influence of long-term tillage on physicochemical properties and greenhouse gas emission. The thickness of arrow appearing in the figure represents the strength of the relationships, additionally, the black arrows and the red arrows indicated positive relationships and negative relationships, respectively. Significance levels were marked: * (p < 0.05); ** (p < 0.01). Different numbers adjacent to the arrows symbolize standardized path coefficients. NH4+-N, ammonium nitrogen; TN, total nitrogen; TOC, total organic carbon