Figure 1.

Physicochemical properties and nutrient contents of the substrate at different stages. (a) Water content; (b) pH; (c) organic carbon; (d) microbial biomass carbon; (e) C/N ratio; (f) total nitrogen; (g) alkali-hydrolyzed nitrogen; (h) nitrate nitrogen; (i) ammonium nitrogen; (j) microbial biomass nitrogen; (k) total phosphorus; (l) quickly available phosphorus; (m) microbial biomass phosphorus. A, B, C, D, and E represent the needle stage, the button stage, the egg stage, the elongation stage, and the maturation stage, respectively. Different letters indicate statistically significant differences.