2.3 Soil sample collection and pre-treatment
Soil samples were collected in mid-July 2020. Soil samples were collected using soil samplers (0-15 cm deep, 5 cm inside diameter), and five random samples were collected from each plot and mixed to a composite sample. Soil samples were sieved and divided into three parts: One part was stored at -80°C for soil microbial DNA extraction, another part was air-dried and used for soil chemical property determination, the rest part was used to determine the composition of soil aggregates and measures the content of GRSP.