Negative correlation between soil salinity and soil organic carbon variability

• 成果类型: Article
• 署名作者: Hassani, Amirhossein; Smith, Pete; Shokri, Nima
• 署名单位: NILU; University of Aberdeen; Hamburg University of Technology
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-13707
• DOI: 10.1073/pnas.2317332121
• 发表日期: 2024-04-30
• 关键词: generalized additive-models; salt-affected soils; land-use; matter content; climate; DECOMPOSITION; DYNAMICS; texture; salinization; temperature

摘要

Soil organic carbon (SOC) is vital for terrestrial ecosystems, affecting biogeochemical processes, and soil health. It is known that soil salinity impacts SOC content, yet the specific direction and magnitude of SOC variability in relation to soil salinity remain poorly understood. Analyzing 43,459 mineral soil samples (SOC < 150 g kg(-1)) collected across different land covers since 1992, we approximate a soil salinity increase from 1 to 5 dS m(-1) in croplands would be associated with a decline in mineral soils SOC from 0.14 g kg(-1) above the mean predicted SOC (<(SOC)over bar>(c) = 18.47 g kg(-1)) to 0.46 g kg(-1) below (SOC) over bar (c) (similar to-430%), while for noncroplands, such decline is sharper, from 0.96 above (SOC) over bar (nc) = 35.96 g kg(-1) to 4.99 below (SOC) over bar (nc) (similar to-620%). Although salinity's significance in explaining SOC variability is minor (<6%), we estimate a one SD increase in salinity of topsoil samples (0 to 7 cm) correlates with respective <(SOC)over bar> declines of similar to 4.4% and similar to 9.26%, relative to (SOC) over bar (c) and (SOC) over bar (nc). The (SOC) over bar decline in croplands is greatest in vegetation/cropland mosaics while lands covered with evergreen needle-leaved trees are estimated with the highest (SOC) over bar decline in noncroplands. We identify soil nitrogen, land cover, and precipitation Seasonality Index as the most significant parameters in explaining the SOC's variability. The findings provide insights into SOC dynamics under increased soil salinity, improving understanding of SOC stock responses to land degradation and climate warming.