Distinct Observable and Measurable Pedogenic Features of the Floodplain Soils as Criteria to Assign a Separate Order in USDA Soil Taxonomy

摘要

Floodplain soils show distinct observable and measurable pedogenic features like identifiable nature of depositionai regime, polygenic origin, organic carbon and CaCO_3 distribution, textural variation, lithological discontinuity, pedogenic alteration, colour change, salt encrustation and natural vegetation as affected chiefly by hydrology on periodical basis. The features observed are not taken care of appropriately in Soil Taxonomy for classification. Fluvent or even Aquent are not safely aligned to many of the properties of floodplain soils that directly contribute to the conservation as well as management package needed for sustainable production of these soils. Vertic properties are also common among these soils, which have been derived through the influence of back water, but they are not the true Vertisols and need special management packages for crop production. The soils are chemically unstable and dynamic as affected by hydrological cycle. Chemihydropedoturbation is a very selective pedoturbation in floodplain soils wherein dissolved organic and inorganic chemicals as well as sediments undergo churning as a function of fluctuating flood water that covers the soil surface appreciably during flood. Based on some distinct features as well as their potential production capability it is advisable to assign a separate Order in Soil Taxonomy for floodplain soils. The Indo-Gangetic plain of India is known for its vast area under various categories of such soils.