Importance of biogenic silicon in pedological sequences, as a determinant of the edaphic properties of agroecosystems of the argentinian pampean plains

Abstract

Silicon (Si) is the second element of importance in the litosphere found mostly as silicate and biogenic silica essential for many organisms. Particularly amorphous silica biomineralizations of vegetal origin (silicophytoliths) can be found in many plant families being the grasses (wild types and crops) their major producers with sizes between 5 and 50 mμ. After plant decomposition this biomineralizations are incorporated pre-sin and postpedogenetically into the soil modifying its physicochemical mineralochemical and biological properties. Minerachemicaly was analyzed by petrographic and scanning electron microscopy MEB and EDAXs while Si in soil solution was measured by UV-VIS spectrophotometry all trough routine techniques. Results from the physicochemic mineralochemic and biological analysis proves the presence of different well-preserved silicates and also a relevant amount of silicophytoliths in the southeastern Argiudolls of the Buenos Aires province explained by the dominant coverings of grasses in the meadows of the extensive Cenozoic. From the physical point of view the silt fraction is a major component of the skeletal fraction of the aggregates which confer structural stability providing favorable physical conditions such as porosity infiltration and transport that will lastly affect the mobility of soil solutions. Silicophytoliths constitute a relevant textural fraction to which the conservative managements applied during last decades had contributed to preserve since they allowed high amounts of them to be incorporated into the soils. On the other side the irrational managements had drastically modified and depleted the soil profiles from silicophytoliths stocks. Therefore managements are considered the main controllers of these biomineralizations stocks that will lastly contribute to the aggregate?s stability preservation since they will enrich their matrix with amorphous silica associated to the soil organic matter. Finally as biomineralizations are an116important component of the organic-inorganic soil phases it`s considered relevant to plan adequately the use of silicophytolith´s supplier crops as a tool for the mitigation of the negative effects suffered over hundreds of years and the improvement and preservation of edaphic properties.