Silicophytoliths and silicon studies by field assays in mollic epipedons of the southeastern Pampean plains, Argentina

OSTERRIETH L. MARGARITA; FRAYSSINET, CELIA; BENVENUTO, LAURA; BORRELLI, NATALIA; MARA DE RITO; FERNANDEZ HONAINE, MARIANA

Congreso; 10th International Meeting on Phytolith Research; 2016

Silicon is the second most abundant element in the earth?s crust. It is essential for the normaldevelopment and growth of plants, and plays a key role in the physical, chemical and biologicalsoil properties. Silicon is important in the formation of inorganic matrix and supporting structures, which in turn condition the availability and mobilization of basic elements,such as C, O, P,Al, and trace elements. Amorphous silica biomineralizations (silicophytoliths) constitute a significant source of silicon to the soil-plant-atmosphere system, as they dissolve faster than silicateminerals. However, their role in agronomic aspects related to the loss of physical, chemical andbiological fertility is still poorly documented. Research on the importance of silicon nutritionin order to promote plant growth has been reported in many countries, but not in Argentina.Given the negative e↵ects that the intense agricultural activity has been causing on soils of thePampean Plain, this work aimed at evaluating the silicophytoliths and silicon contribution innatural and experimental soils sowed with two varieties of wheat (Aviso and Baguette), and withthe application of solid (Silfix) or liquid (Quicksoil) silicon fertilizers. The content of silicophytoliths (% dry weight) in wheat was determined by calcination, and the content of SiO2 in soilsolutions was determined through UV-Vis spectrophotometry by the silicomolybdate method.Wheat plants (Triticum aestivum) produced 27 Kg silicophytoliths.ha-1 in the vegetative stage,and 738 Kg silicophytoliths.ha-1 in the maturity stage. Media values of silicon in soil solutionsvaried from 1100 µmol/L in natural soils, to 722 µmol/L in plots with solid silicon fertilizer and635 µmol/L in plots with liquid silicon fertilizer. These results, showing a substantial Si contentdecrease in cultivated soils, are important in order to advance into the knowledge of inputsand losses of silicon in agro-ecosystems. Specially, given the increase of the production of somecrops that are not commonly producers of silicophytoliths/silicon (like soybean) in the PampeanPlain of Argentina. The Argentinian perspectives on agriculture application of silicon fertilizersand silicon enhancement of crops quality were also discussed. This work was supported by theAgencia Nacional de Promoci´on Cient´ıfica y Tecnol´ogica, Ministerio de Ciencia y T´ecnica (PICT1583-2013) and Universidad Nacional de Mar del Plata (EXA 741/15).