Soil Science & Water Conservation accounts for 4 to 6 questions in NABARD Grade A Prelims and Mains. Every aspirant must master ICAR’s 8 Major Soil Groups of India (Alluvial 43%, Red 18.5%, Black/Vertisols 15%, Laterite), Arnon & Stout’s Criteria of Essentiality and the 17 Essential Plant Nutrients (with Nickel added as the 17th by…