Processes in submerged soils - linking redox potential, soil organic matter turnover and plants to nutrient cycling

Background Submerged soils are globally important both in natural and agricultural ecosystems and cover 5-7% of the global land surface. Therefore, processes in submerged soils are important for global biogeochemical cycles. These processes are strongly influenced by oxygen availability, i.e. redox potential. Scope This review aims to provide an overview of the role of redox potential in nutrient cycling, soil organic matter turnover and the effect of plants on nutrient cycling processes in submerged soil. Conclusion In submerged soils, the active terminal electron acceptor for reduction processes follows the sequence O-2, NO3-, MnO2, Fe3+, SO42- and CO2 where, in most cases organic matter, is the electron donor. Depletion of available organic matter during this sequence can limit the subsequent processes. Drying and rewetting of previously submerged soils have complex effects on nutrient cycling. Submerged soils often have higher organic matter content than aerobic soils which is due to chemical, metabolic and physical mechanisms. Plants have complex effects on processes in wetland soils resulting from release of oxygen from roots which can induce iron and methane oxidation around roots. However, plants can also increase methane release due to transport of methane via aerenchyma to the shoots. For a better understanding of processes in submerged soils, future investigations across scales, ranging from microscale to macroscale, are needed.

Automated summary

Submerged soils play a vital role in global biogeochemical cycles, with processes strongly influenced by oxygen availability (redox potential). These soils often have higher organic matter content than aerobic soils, and plants have complex effects on wetland soil processes, both beneficial and detrimental.