Which of the following soil types becomes less fertile due to the intense leaching caused by tropical rains?

1. Analyze the question The question asks which soil type loses fertility because heavy tropical rainfall washes away its nutrients (leaching).

2. Explain the concept Leaching is the downward washing of soluble nutrients (such as calcium, magnesium, potassium and nitrates) out of the topsoil by percolating water. In the humid tropics, where rainfall is heavy, this process is intense. It removes silica and bases, leaving behind iron and aluminium oxides. This produces a reddish, hard, nutrient-poor soil, a process called laterization.

3. Step-by-step solution

• Black soil (regur) forms from volcanic or basaltic rock. It is rich in clay and nutrients and holds water well, so it is fertile and not typically leached. Eliminate D.
• Yellow soil forms in humid regions and is also somewhat leached. However, it is not the classic example the question is looking for. Eliminate A.
• Red soils get their colour from iron oxides and are often loosely described as leached, so they are a close distractor. Still, they are a broader category.
• Laterite soil is the textbook result of intense leaching in tropical rain. Its name comes from the Latin later, meaning brick. Heavy rain removes the nutrients, leaving iron and aluminium oxides that make the soil acidic, poor in humus, and low in fertility. This matches the question exactly.

4. Answer **B.

5. Exam tip Link the keywords: tropical rain + leaching = laterite (laterization). Remember it as "Laterite is Late for nutrients: the rain has already washed them away." Also remember that black soil is the fertile one, which helps you eliminate it quickly.