Q. Consider the following statements:

1. Statement-I: The soil in tropical rain forests is rich in nutrients.
2. Statement-II: The high temperature and moisture of tropical rain forests cause dead organic matter in the soil to decompose quickly.

Which one of the following is correct in respect of the above statements? (UPSC Prelims 2023)
Answer: Statement-I is incorrect but Statement-II is correct
Notes: The correct answer is [D] Statement-I is incorrect but Statement-II is correct.

• Statement-I (Incorrect): Contrary to popular belief, the soils in tropical rain forests (often called Oxisols or Latosols) are generally nutrient-poor and acidic. While these forests support the most lush vegetation on Earth, the nutrients are stored in the living biomass (trees and plants) rather than the soil itself. Heavy rainfall causes intense leaching, where essential nutrients like calcium, magnesium, and potassium are washed away, leaving behind insoluble iron and aluminum oxides.
• Statement-II (Correct): The high temperature and consistent moisture levels in tropical regions create an ideal environment for microbial and fungal activity. Consequently, dead organic matter (leaf litter, fallen branches) decomposes very rapidly.
• Relationship: Because decomposition is so fast, the nutrients released are almost immediately reabsorbed by the shallow roots of the dense vegetation. This "tight nutrient cycling" means the soil remains nutrient-deficient despite the high turnover of organic material.

Historically, when tropical rainforests are cleared for agriculture (Slash and Burn), the soil loses its fertility within a few years because the source of organic matter is gone and the inherent soil quality is poor.