Role of Thermal Exposure in Extraction of Plant Available Silicon from Neutral, Acidic and Alkaline Soils

Silicon, the second most abundant element on the Earth crust, is often considered beneficial for plant nutrition. However, plant available fraction of silicon (Si) is hard to find and extract from many types soils. Soil reaction (pH), temperature and plant uptake are some of the major determinants of Si availability affecting its extraction from soil. In this experiment, neutral, acidic and alkaline soils along with plant samples (whole rice plant) have been collected from farmer's field. Plant samples were processed following existing procedure. Soils are air dried, grinded and passed through a 2 mm pore sieve. Four levels of shaking time (0, 5, 10 and 20 minutes and denoted as S-0, S-5, S-10, and S-20,respectively) @ 120rpm (round per minute) and four levels of temperatures (room temperature or 25 degrees C, 60 degrees C, 80 degrees C, and 100 degrees C; denoted as T-0, T-60, T-80 and T-100, respectively) were employed for preparation of aliquot from soil-water (1:10 ratio) suspension. Acidic and alkaline soils have higher extractable silicon than neutral soil. Combined effect of shaking time and temperature released higher Si values than control, amongst which Si extracted from S20T100 treatment is significantly correlated with Si content in rice and have better result for all soils in common.