Abstract

Soil texture plays a crucial role in organic matter (OM) mineralization through both direct interactions with minerals and indirect effects on soil moisture. Separating these effects could enhance the modelling of soil organic carbon (SOC) dynamics under climate change scenarios. However, the attempts have been limited smallscale experiments. Here, we studied the effects of soil texture on added OM mineralization in loamy sand, loam and silt loam soils in nine agricultural fields in Flanders, Belgium. Soil moisture, temperature, groundwater table depth and the mineralization of 13C-labeled ryegrass were monitored in buried mesocosms for approximately three months during a dry summer. Ryegrass-C mineralization was lowest in the loamy sand (39 & PLUSMN; 7 %) followed by silt loam (48 & PLUSMN; 7 %) and loam (63 & PLUSMN; 5 %) soils, challenging the current clay%-based moderation of Cmineralization rates in soil models. Soil temperature was not influenced by soil texture, whereas soil moisture was indeed dependent on soil texture. It appears that capillarity sustained upward water supply from groundwater to the topsoil in loam and silt loam soils but not in loamy sand soil, although this difference in capillary rise could not fully explain the higher moisture content in loam than that in silt loam soils. Additionally, soil texture only impacted remnant added ryegrass pieces (>500 & mu;m) but not the finer ryegrass-derived SOC (<500 & mu;m), which might point at the important indirect control of texture on OM mineralization during prolonged summer drought. However, these effects are only manifested during drought when no other factors (e.g., groundwater depth or subsurface water flows) exert an overriding impact on the soil water balance. Overall, our findings highlight the need to properly incorporate the indirect effects of soil texture on OM mineralization into soil carbon models to accurately predict soil C stocks under future climate change scenarios.

Keywords

Capillary rise; Groundwater; Soil moisture; Soil organic carbon; Stable carbon isotope

Published in

Science of the Total Environment
2023, Volume: 899, article number: 165749

SLU Authors

• Li, Haichao

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    
  • Ghent University

• Zhang, Shengmin

  • SLU Swedish Species Information Centre, Swedish University of Agricultural Sciences
    

Sustainable Development Goals

Take urgent action to combat climate change and its impacts


UKÄ Subject classification

Soil Science


Publication identifier

DOI: https://doi.org/10.1016/j.scitotenv.2023.165749

Permanent link to this page (URI)

https://res.slu.se/id/publ/123692