Which soil order in the USDA soil taxonomy is typically characterized by high concentrations of shrinking and swelling expanding clays, leading to deep cracks during dry seasons?

💡 Solution & Explanation

Vertisols represent a major soil order in USDA taxonomy characterized by a high proportion of expanding smectite clays that swell upon wetting and shrink drastically during dry periods, creating wide surface cracks. Other soil orders like Spodosols or Oxisols form under distinct climatic and leaching conditions without possessing this characteristic self-mulching property. These soils correspond largely to regur or black cotton soils found extensively in peninsular India. Vertisols exhibit high fertility and moisture retention capacity, making them exceptionally suitable for rainfed cotton cultivation.