Allophanes, a significant soil pool of silicon for plants

While in tropical soils recycling of plant phytoliths has been shown to represent a major pool Si available for plants, the main pools plants temperate are still poorly constrained. We characterised various forested and cultivated France by selecting seven paired sites (adjacent wheat forest plots) four soil groups: Luvisols, Albeluvisols, calcaric hypereutric Cambisols. showed that CaCl2-extracted (bioavailable) is mostly controlled pH allophanes (short-range ordered aluminosilicates) but not phytoliths. Cultivation, decreasing organic carbon content increases allophane SiCaCl2 concentration. Our work highlights importance as missing link between solution clay minerals could explain reported correlation mineral bioavailable Si.