Effects of long-term management measures on soil enzyme activity and microbial nutrient dynamics in an arid environment: A case study from the Southern Taklimakan Desert

Soil enzyme activity is important for indicating soil microbial nutrient demand and limitation. Yet, our knowledge of eco-enzymatic stoichiometry and microbial nutrient uptake in arid environments is restricted. This research, conducted at the southern boundary of the Taklimakan Desert, involved an examination of the soil's nutrient levels, microbial biomass, and enzymatic activities under different long-term management measures, including the control group (CK), cutting in spring (CS), cutting in fall (CF), burning in spring (BS), and floodwater irrigation (FI). The results of the research show that the use of CS led to a notable rise in soil organic carbon (SOC) and available potassium (AK) in comparison to FI. Additionally, the soils subjected to various management measures (CK, CS, CF, BS, and FI) exhibited a high level of nitrogen limitation. In CK, soil microbial nitrogen metabolism increased along with microbial carbon metabolism. In CS, the impact of soil available phosphorus (AP) and total potassium (TK) on soil microbial biomass, enzyme activity, and microbial carbon and nitrogen metabolism was significant, with a respective contribution of 4.65 % and 1.91 %. In the context of CK, the available nitrogen (AN) in the soil played a significant role in soil microbial biomass, enzyme activity, and microbial carbon and nitrogen metabolism, contributing 5.92 %. Within the BS, soil total nitrogen (TN), SOC, and pH exerted significant influences on soil microbial biomass, enzyme activity, and microbial carbon and nitrogen metabolism, contributing 7.16 %, 6.70 %, and 1.62 % respectively. Within the context of FI, soil TN and SOC contributed to 7.16 % and 6.70 % of soil microbial biomass, enzyme activity, and microbial carbon and nitrogen metabolism. In CK, soil AN: AP was significantly negatively correlated with soil leucine aminopeptidase (LAP). In CS and BS, soil TC:TP (soil organic carbon and total phosphorus ratio) and TN:TP was significantly positively correlated with soil β-1,4-glucosidase (BG), inversely, soil TC:TN was significantly negatively correlated with soil β-D-cellobiosidase (CBH). Structural equation model indicated that soil AN: AP, soil TC:TN:TP were negatively correlated with soil enzyme activity. This study emphasizes the importance of adopting sustainable management strategies to safeguard and rehabilitate soil functionality, thereby enhancing the overall health and resilience of ecosystems in highly arid regions.