EVALUATION OF DIFFERENT EXTRACTANTS FOR AVAILABLE SILICON IN USTOCREPT SOILS OF GUJARATJ. K. Malav, K. C. Patel, Mohammad Sajid, Ramesh Gurjar and Mahesh Agarwal
A survey was carried out in paddy growing area of Anand and Kheda district of middle Gujarat to know the available silicon (Si) status in soils of paddy fields. Total sixty surface soil samples were collected and categorized as per available Si status as low, medium and high categories and out of these samples representative bulk soil samples were taken to conduct pot experiment for evaluation of different extractants for available Si and response to Si application by paddy in goradu soils of middle Gujarat. The soils were treated with four levels of Si viz., 0, 100, 200 and 300 mg Si kg soil-1. The experiment was planned in factorial completely randomized design with three repetitions. The coefficient of correlation (r) and regression (R2) were also worked out for different extractants with important soil and plant properties. The available Si in soils extracted by H2O, CaCl2, NaOAc, NH4OAc, phosphate + acetic acid and phosphate buffer ranged from 8.61 to 17.11, 12.14 to 24.66, 32.30 to 51.31, 34.94 to 47.77, 51.73 to 72.42 and 54.68 to 78.22 mg kg-1, respectively. The NaOAc and NH4OAc, phosphate + acetic acid and phosphate buffer extracted around 3 and 4 times more available Si from soils than H2O and CaCl2. In low category soils, NH4OAc extractable available Si recorded highest correlation coefficient (r) value with grain yield (r=0.589**), Si content in grain (r=0.371*) and straw (r=0.691**), Si uptake by grain (r=0.524**) and straw (r=0.736**). In medium and high category soils, NH4OAc as well as CaCl2 noticed maximum relationship with different parameters. The highest regression coefficient was obtained for grain yield (R2=0.614**), straw yield (R2=0.335*), Si content in straw (R2=0.681**) and Si uptake by straw (R2=0.715**) with available Si extracted by phosphate + acetic acid. Based on ranking methodology, the extractants could be arranged on the basis of Si uptake by paddy as: phosphate + acetic acid > CaCl2 > NaOAc > phosphate buffer > NH4OAc > H2O. The overall relationship of available Si extracted by phosphate + acetic acid was proved better with silicon uptake by paddy, hence it could be considered as suitable extractant for available Si in paddy soils of middle Gujarat.
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