Silicon (Si), being a quasi-essential element for plant nutrition, is considered as an essential element for silicophilic plant species like rice and sugarcane. It is the second most abundant element in the earth’s crust. This study aims to investigate the availability of Si in soils with two different extractants viz., NH_4OAc and NH_4OAc-PO_4 buffer and their relationships with some important soil physicochemical properties in intensively rice growing areas of two major agro-climatic zones namelyTerai and new alluvial zones covering five districts of West Bengal. Results revealed that extractable Si in soils varied from 7.50 to 75.0 and 12.5 to 120.5 mg kg~(-1) with a mean value of 24.9 and 50.8 mg kg~(-1) for NH_4OAc and NH_4OAc-PO_4 buffer, respectively. Irrespective of soil types, the NH_4OAc-PO_4 buffer always extracted higher amount of Si from the soil than NH_4OAc. Soils belonging to the new alluvial zones covering districts Nadia, Hooghly and Barddhaman have higher extractable Si content, whereas soils belonging to the Terai zone showed lowest in its content. On the basis of critical value, all soils of Cooch Behar and Jalpaiguri districts and 50.0, 60.0 and 70.0 of the soils of Nadia, Barddhaman and Hooghly districts, respectively, are found deficient in available Si for growing rice, indicating need for the application of external Si sources for higher crop production. Results further indicated that the extractable Si content in soils were significantly and positively correlated with pH, cation exchange capacity and clay content, whereas, significant negative correlation was observed between NH_4OAc-PO_4 extractable Si with organic carbon content of the soils.
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