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Updated: Jun 2, 2026

Monitoring Pedogenic Inorganic Carbon Accumulation Due to Weathering of Amended Silicate Minerals in Agricultural Soils.
Published on: June 4, 2021
Oxalic acid-mediated phosphorus availability regulates the variations of karst soil organic carbon fractions under
Daxiang Ye1,2,3, Ke Wu1,2,3, Yueming Liang4
1Guangxi Key Laboratory of Environmental Pollution Control Theory and Technology/College of Environmental and Engineering, Guilin University of Technology, Guilin, China.
Abstract:
Soil organic carbon (SOC) pool in terrestrial ecosystems is increasingly threatened by drought and altered root exudates input under global climate change, but mechanisms changing SOC fractions [Dissolved organic C (DOC), Particulate organic C (POC), Mineral-associated organic C (MAOC), Microbial biomass C (MBC)] in fragile karst ecosystems remain unclear. This study investigated drought (100%, 70%, and 35% field capacity) and the types and input concentrations of exudates (glucose, glycine, and oxalic acid) on SOC fractions through a 90-day incubation experiment with karst shrubland soils from southwest China. The results showed that DOC accumulated associating with reduced microbial and enzymatic activities under drought, while MAOC remained stable. The input of exudates resulted in a reduction in DOC, while simultaneously increasing the activities of β-glucosidase and leucine aminopeptidase under drought. Additionally, the changes in the POC, MBC, total SOC, and the enzyme activities resulting from the input of oxalic acid were slightly more obvious than those caused by glucose and glycine. Random forest models showed that the POC, MAOC, and total SOC were significantly impacted by drought time, available phosphorus (AP), and microbial biomass, while DOC was significantly affected by MBC and βG activity. Additionally, the structural equation models indicated that AP might be a crucial influencing factor in the changes of SOC. This is because of AP was influenced by the drought intensity and time and the exudates input, which in turn constrained microbial and enzyme activities and ultimately affected the changes in karst soil organic C fractions. These results enhanced the understanding of the changes in soil organic C and suggested that when implementing ecological restoration projects, intercropping species with drought tolerance, deep roots, and high oxalic acid exudation into plant communities can be beneficial for the ecological restoration and soil organic C sequestration of karst ecosystems.
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