Root silicification of grasses and crops from the Pampean region and its relevance to silica and silicophytolith content of soils.

Aims: Silicophytoliths contribute to the pool of amorphous silica that is incorporated into the soils acting as intermediary in the biogeochemical cycle of silicon. Most studies focus their attention in the production of aerial parts of plants but not in roots. In order to advance into the knowledge about the relevance of root amorphous silica in soil Si cycle, we studied the silicophytolith content of roots from grasses and crops, and from soil's roots of different sites from Pampean region, Argentina, one of the most fertile and used for agricultural practices. Methods: Roots from three crops and seven grasses and from soils under three different uses were studied. Silicophytoliths were extracted by a calcination technique. Results: All the species produced silicophytoliths derived from vascular and/or endodermal tissues. Silicophytolith content was higher in Pampean grasses (6.34–15.38%) than in crops (0.01–1.58%). Root silicophytolith content in the pasture was 10 times higher than in the other sites. Conclusions: The potential input of root silica to soils is related to the type and cover of vegetation, the amount of roots in soils and the silicophytoliths accumulated in roots. Results suggested that root silicophytoliths should be consider in future studies of biogeochemical cycle of Si. [ABSTRACT FROM AUTHOR]