Comparison study of soil silicon status in sandy soils of south Florida

Silicon (Si) is the most abundant element in earth's crust after oxygen. So il contains various mineral and soluble forms of Si compounds. The biogeoch emical cycle of Si in the soil-plant system involves leaching, horizontal m igration and adsorption by plants. Soluble Si compounds determine and contr ol many soil properties including P, Al and heavy metal behavior, soil adso rption properties, and, probably, soil structure. Two main types of soil Si cycles are accumulative and eluvial. Florida sandy soils are characterized by an eluvial Si cycle. The aim of investigation was to test the soil Si s tatus in native and cultivated Alfisols, Spodosols, and Entisols from sever al counties in south Florida. The content of monosilicic acids, polysilicic acids, and acid-extractable Si was determined in surface (0-20 cm) and sub surface (20-40 cm) soils. All soils tested extremely low in plant-available and biogeochemically active Si compounds, which suggests that the sandy so ils in south Florida need Si fertilization.