As a consequence, Si isotope signatures in the clay fraction of soils should be tested in other systems to trace the modifications of pedogenic clay minerals insoil–plant systems, such as developed in highly weathered tropical and subtropical environments (Ferralsols, Lixisols, Nitisols, …), in frozen soils (Cryosols), in soils characterized by illuviation of clay minerals (Luvisols), in young soils (Cambisols) and in soils with high biological activity (Chernozems).