Soil nutrient content and the activities of soil enzymes during the desertification restoration process to the east of Qinghai Lake

This study focused on the artificial grasslands established with three different plant species Elymus dahuricus (Ely), Puccinellia distans (Puc) and Poa annua (Poa) for five years to control desertification to the east of Qinghai Lake. To assess the effects of these three artificial grasslands on sand soil nutrient content, soil enzyme activities and their relationships, we analysed soil nutrient (nitrogen, phosphorous, and potassium) and organic matter contents, as well as the activities of three soil enzymes, namely, urease, catalase, and invertase. The results showed that: 1) soil nutrient and soil enzyme activity were significantly improved after the grasses were planted. 2) Compared with the other two treatments, Poa had significant effects on improving soil organic matter, available nitrogen, available phosphorus, total potassium, and available potassium. The soil nutrient content had a significant positive relationship with soil urease activity. 3) Soil urease activity was much greater in the Ely and Poa treatments, and the activities in all the three treatments were higher than the control in the surface soil layer. In the 0-20 cm soil layer, the activities of soil catalase in the three treatments were higher than that in the control, with Poa showing the highest activity. All three treatments showed no significant effect on the activity of soil invertase. 4) The activities of soil urease and catalase both had a general significant relationship with soil nutrient content, which could be taken as the effective index for the measurement of desertification control process.