Water and Wind Erosion Mechanics, Universal Soil Loss Equation (USLE/RUSLE), Erosivity & Erodibility - Water Science and Technology | Agrigyan

• Inceptisols Order in India: Inceptisols are weakly developed, young mineral soils characterized by embryonic diagnostic horizon differentiation (such as a cambic $B$ horizon) showing alterations of color or structure without significant clay illuviation.
• Dominance: Inceptisols represent the single largest soil order in India, covering approximately 39.4% (about 130 million hectares) of the country's total geographical area, predominant across the vast Indo-Gangetic alluvial plains and river basins. (Correct answer: Option 3)
• Entisols: Second most abundant order (~28% of TGA), showing no diagnostic pedogenic horizons.
• Alfisols: Third most extensive order (~13% of TGA), characterized by an argillic horizon with medium-to-high base saturation.
• Mollisols: Grassland soils with thick, dark mollic epipedon, limited to high-altitude Himalayan zones in India.

• Oxisols: The most extremely weathered and pedogenically advanced soil order in USDA Soil Taxonomy.
• Characteristics: Dominated by an oxic subsurface diagnostic horizon composed almost entirely of low-activity 1:1 clays (kaolinite) and residual sesquioxides of iron and aluminum (goethite, gibbsite, hematite), with virtually all primary weatherable minerals depleted.
• Comparison: Inceptisols are weakly developed young soils; Vertisols are expanding 2:1 clay soils; Alfisols show moderate weathering with argillic horizons. (Correct answer: Option 3)

• Statement (I) is True: In soil conservation and dryland farming, wind strip cropping utilizes strips of erosion-resistant crops alternating with erosion-susceptible crops perpendicular to the prevailing wind direction to arrest wind erosion.
• Statement (II) is False: Strip width is not fixed for all soils; rather, strip width must be narrower on coarse textured sandy soils ($6-20\text{ m}$) where wind detachment is severe, and can be broader on cohesive clay/loam soils.
• Conclusion: Statement (I) is true but Statement (II) is false (Option 3).

Correct option: (3) Statement (I) is correct but Statement (II) is incorrect.

• Stream Bed Load Transport Modes:
• Total sediment load in open stream channels consists of suspended load, dissolved load, and bed load.
• Bed Load: Coarse mineral particles that move in continuous or intermittent contact with the channel bed via Saltation (hopping and bouncing) and Surface Creep (rolling and sliding along the bed floor). (Correct answer: Option 3)