A soil, which has pH more than 8.5, ESP more than 15, and EC less than 4 dS/m is called:

Correct option is B

The correct answer is (B) Alkali Soil

Explanation:
• Alkali soils (also known as Sodic soils) are characterized by high levels of Exchangeable Sodium Percentage (ESP > 15).
• These soils have a pH range typically between 8.5 and 10.0 due to the hydrolysis of sodium carbonate.
• The Electrical Conductivity (EC) is relatively low (less than 4 dS/m) because soluble salts have been leached, but sodium remains on the exchange complex.
• The presence of excessive sodium causes soil dispersion, leading to poor physical structure and restricted water movement.

Information Booster:
• Reclamation of alkali soils usually involves the application of Gypsum ($CaSO_{4}·2H_{2}O$) to replace sodium ions with calcium ions on the soil clay complex.
• These are often referred to as 'Black Alkali' soils because dissolved organic matter accumulates at the surface, giving it a dark color.

Additional Knowledge:
• Saline Soil (Option A): pH < 8.5, ESP < 15, but EC > 4 dS/m. Known as 'White Alkali'.
• Saline-Alkali Soil (Option C): pH varied (usually < 8.5 but can be higher), ESP > 15, and EC > 4 dS/m.
• Degraded Alkali Soil (Option D): Occurs when a sodic soil is leached of its soluble salts in the absence of calcium, resulting in a very low pH in the top layer and a dense B-horizon.