Soil Chemical and Enzymatic Analysis

Soil samples with roots and debris removed using a 2 mm sieve were air-dried and stored at 4 °C for use. Fourteen common environmental factors in soil were detected according to previous studies, including available phosphorus (AP), available potassium (AK), ammonium nitrogen (AN), soil organic matter (SOM), total organic carbon (TOC) (Bao, 2000 ), nitrate nitrogen (NN) (Sun et al., 2016 ), Saccharase (SC), Urease (UE), alkaline phosphatase (AKP) (Guan, 1986 ); total nitrogen (TN), total hydrogen (TH), total carbon (TC), and total sulfur (TS) were detected by Elemental Analyzer (Elementar vario EL cube Elemental Analyzer; Elementar, Langenselbold, Germany) and the pH of soil samples was determined in 1:2.5 soil-water suspension using pH meter (Sartorius PB-10). The saccharase activity was expressed as mg glucose·d⁻¹·g⁻¹ soil, the urease activity was expressed as mg NH₃-N·d⁻¹·g⁻¹ soil and the alkaline phosphatase activity was expressed as mg P₂O₅·2h⁻¹·g⁻¹ soil.