Figure 4

Soil enzyme activity under different fertilizer treatments. Treatments included control (CK), chemical fertilizer only (CF), and a series of chemical fertilizer to organic fertilizer ratios (OM1–4). (A) Soil urease (S-UE) activities. (B) Soil alkaline phosphatase (S-AKP) activities. (C) Soil sucrase (S-SC) activities. (D) Soil catalase (S-CAT) activities. Columns represent the means ± SDs for five biological replicates. Treatments with the same letter are not significantly different from each other at an alpha level of 0.05 (LSD post hoc test).