Arid Zone Research ›› 2024, Vol. 41 ›› Issue (11): 1969-1980.doi: 10.13866/j.azr.2024.11.16

• Agricultural Ecology • Previous Articles    

Simulated effects of soil enzyme activity on soil organic carbon mineralization in dam land under dry and wet conditions

XING Xinran1(), ZHANG Yi1(), LI Peng2, LIU Xiaojun3, TAO Qingrui4, REN Zhengyan4, XU Shibin5   

  1. 1. College of Ecology and Environment, Ningxia University, Yinchuan 750021, Ningxia, China
    2. National Key Laboratory Cultivation Base of Ecological Water Conservancy Project in Northwest Arid Region, Xi’an University of Technology, Xi’an 710048, Shaanxi, China
    3. College of Agriculture, Ningxia University, Yinchuan 750021, Ningxia, China
    4. Soil and Water Conservation Monitoring Station of Ningxia Hui Autonomous Region, Yinchuan 750002, Ningxia, China
    5. Xiji Indiscriminate Mud River Basin Soil and Water Conservation Test Workstation, Xiji 756200, Ningxia, China
  • Received:2024-04-21 Revised:2024-06-12 Online:2024-11-15 Published:2024-11-29
  • Contact: ZHANG Yi E-mail:13099525526@163.com;yzhang026@nxu.edu.cn

Abstract:

Climate change has increased the frequency of long-term droughts and heavy rainfall events, impacting ecosystems’ carbon cycle. Therefore, understanding how soil enzyme activity in different dry/wet conditions affects organic carbon mineralization can help deepen our understanding of the carbon cycle mechanism and advance the goal of global carbon neutrality. This study was based on the unique terraces built to control erosion in the Loess Plateau, and three treatments of flooding stress, drought stress, and wet/dry cycles were designed to monitor soil enzyme activity and organic carbon mineralization. The results indicate that the wet/dry cycle has a transient stimulating effect on organic carbon mineralization, and the cumulative mineralized organic carbon occurs between the drought and flooding stress. At the same time, the wet/dry cycle will increase the activity of carbon and nitrogen cycle-related enzymes; however, the enzyme activity will gradually decrease and stabilize as the number of cycles increases. The enzyme activity in all three water treatment conditions was limited by carbon and phosphorus, and the carbon limitation was more substantial with increasing wet/dry cycles. After the fourth alternating wet/dry cycle, the phosphorus limitation exceeded the flooding and drought stress treatments. When the soil was under drought stress, flooding stress, or wet/dry cycles, the enzyme activity factors that limit organic carbon mineralization were different. The direct effect of the phosphatase factor under drought stress was 99%, the direct impact of EAAC/N (carbon cycle- /nitrogen cycle-related enzyme) and xyloglucosidase factor under flooding stress was 87%, and the direct effect of the interaction between factors under drought and flooding stress was only 1% and 13%. Under wet/dry cycle conditions, the direct impact of phosphatase and N-acetyl-beta-glucosaminidase factor was 75%, the direct effect of interaction between factors was 25%, and the wet/dry cycle significantly increased the interaction between factors. This study provides theoretical support for clarifying the role of Loess Terrace.

Key words: dry and wet alternate, soil enzymes, soil organic carbon mineralization, Loess Plateau