Cropping Systems & Sustainable Agriculture

• Cat clays (acid sulfate soils with high iron pyrite/jarosite deposits that develop extreme acidity of pH < 3.5 upon aeration and drainage) are extensively found in the coastal backwater and swampy Kuttanad and Pokkali tracts (locally designated as Kari soils) of Kerala.
• Karnataka coastal strips have lateritic soils.
• Tamil Nadu has deltaic alluvium and vertisols.
• Assam soils are acidic riverine alluvial tracts without cat clay characteristics.

• CaCO3 is limestone or calcitic agricultural lime.
• Ca(OH)2 is slaked lime or hydrated lime.
• Quick lime (burnt lime or unslaked lime) is anhydrous Calcium Oxide, having the chemical formula CaO, produced by thermal calcination of limestone: CaCO3 + heat -> CaO + CO2.
• CaCO3.MgCO3 is dolomite.

In the USDA Wind Erosion Equation (WEQ), K represents the soil ridge roughness factor (soil surface roughness).

• Soil erodibility factor: Represented by 'I' in the equation, which relates to soil aggregate stability.
• Slope gradient factor: Represented by 'S' in the Universal Soil Loss Equation (USLE), not present in WEQ.
• Climatic factor: Represented by 'C' in the equation, accounting for wind speed and surface soil moisture.
• Soil surface roughness: Represented by 'K' (soil ridge roughness factor), which measures the degree of surface roughness formed by tillage ridges.

• Mushroom rocks (pedestal rocks) are characteristic aeolian landforms formed by differential wind erosion (sandblasting and abrasion) near ground level where suspended abrasive sand grains are concentrated.
• Water erosion produces gorges, gullies, and stream terraces.
• Exfoliation is physical peeling of outer curved rock sheets driven by thermal fluctuations.
• Moraines are accumulations of unsorted glacial debris.