Question

Alluvial soils vary in nature from sandy loam to clay. They are generally -

• A. Poor in potash and rich in phosphorus
• B. Poor in both potash and phosphorus
• C. Rich in both potash and phosphorus
• D. Rich in potash and poor in phosphorus

Hint:

Indian soils, especially Alluvial soils, are typically:
- Rich in: Potash
- Deficient in: Nitrogen (N) and Phosphorus (P)
This is why balanced NPK fertilization is recommended.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Alluvial soil is the largest and most fertile soil group in India, covering about 40% of the country's total land area, primarily across the Indo-Gangetic plains.
Understanding the chemical composition and nutrient status of these soils is essential for optimal fertilizer management.

Step 2: Detailed Explanation:
Alluvial soils are formed by the deposition of silt and sediment carried by major rivers like the Indus, Ganges, and Brahmaputra.
- Potash Status: These soils are derived from weathered rocks upstream that are rich in potassium-bearing minerals like illite and feldspars. Consequently, alluvial soils are generally rich in potash (potassium, K).
- Phosphorus Status: In contrast, the organic matter and mineral sources of phosphorus in these river basins are relatively limited. As a result, alluvial soils are generally poor to deficient in phosphorus (P), as well as nitrogen (N) and organic carbon.
Therefore, the general chemical profile of alluvial soils is characterized by being rich in potash but poor in phosphorus.

Step 3: Final Answer:
Alluvial soils are generally rich in potash and poor in phosphorus.