2.4 Soil enzyme activity
Soil enzyme activity for various treatments were shown in Fig.1. With the increase of soil depth, the Urease, alkaline phosphatase and sucrase enzyme activity was decreased, and catalase enzyme activity was increased. Compared with TS, the TSD increased and TD significantly decreased the Urease enzyme activity in the 0-30 cm soil depth. The Urease enzyme activity was in order of TD < TS < TSD in 10-20cm and 20-30cm soil layers, but was in order of TD < TSD < TS in 0-10cm soil layers. The alkaline phosphatase enzyme activity in same soil layers was in order of TD < TSD < TS, and the TSD and TD significantly decreased the alkaline phosphatase enzyme activity in the 0-30 cm soil depth compared with TS. The catalase (except in 20-30cm soil layers) and sucrase enzyme activity showed the same trendas changes in alkaline phosphatase enzyme activity.