2.2 Soil physical and chemical characteristics
Soil bulk density, total porosity and pH for various treatments were shown in Table3. The soil bulk density gradually increased in TS and increased in TSD and TD with the increase of soil depth. Compared with TS, the TSD and TD significantly increased the soil bulk density in the 0-30 cm soil depth. Soil bulk density was in order of TS < TSD < TD in same soil layers. The soil total porosity showed the opposite trend as changes in soil bulk density, and the pH showed the same trend as changes in soil bulk density except the pH in 10-20cm soil layer (TS < TD < TSD). Except TS, the total N gradually increased with the increase of soil depth. From Table4, compared with TS, the TSD and TD significantly decreased the soil total N in the 0-30 cm soil depth, and soil total N in same soil layers was in order of TD < TSD < TS. The SOC showed the same trend as changes in total N (Table4). The total P in same soil layers was in order of TSD < TD < TS (Table4), and the TSD and TD significantly decreased the total P in the 0-30 cm soil depth compared with TS. Available P showed the same trend as changes in total P (Table3). The available K in same soil layers was in order of TSD < TS < TD, except in 0-10cm soil layers (Table3).