Role of silicon in phytolith-occluded carbon (PhytOC) sequestration

The sequestration of carbon (C) has been recognized as a crucial step in reducing global warming. Terrestrial biogeochemical C sequestration, coupled with silicon (Si) cycle through mechanisms of phytolith-occluded carbon (PhytOC) is considered as one of the promising approaches for long-term soil C sequestration. Si being a prerequisite for phytolith formation, plays a fundamental role in PhytOC sequestration. The use of exogenous Si amendments in Si-deficient soils offers a possibility of enhancing C sequestration through PhytOC. This review discusses the Si induced C sequestration in phytoliths, highlighting the sources of C and the mechanisms of its occlusion in phytoliths, different fractions of Si in soils, factors affecting plant available Si (PAS) and PhytOC estimation, and sources of Si fertilizers. The article concludes by identifying knowledge gaps that require further research to reduce the uncertainties associated with Si induced PhytOC sequestration.