Question

Concept of nutrient pumping in agroforestry is based on tree roots extending into

• A. O horizon
• B. A horizon
• C. C horizon
  - Option (D) Water table

Hint:

Tree = Deep Pump. Crop = Surface user. Together, they utilize the entire soil profile, making the land more productive overall.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
"Nutrient Pumping" is a major ecological advantage of agroforestry systems. It refers to how trees improve the nutrient status of the surface soil for crops.
Detailed Explanation:

• The Process: Many essential nutrients (like Nitrate or Potassium) leach out of the shallow root zone of agricultural crops and accumulate in the deeper layers of the soil profile.

• Deep Roots: Trees have deep taproot systems that extend into the lower horizons, such as the C horizon or the lower B horizon.

• The "Pump": The tree roots absorb these "lost" nutrients from the deep layers. These nutrients are then used to build leaves and branches.

• Recycling: When the leaves fall (litterfall) or are pruned and added to the soil as mulch, they decompose. This releases the nutrients back into the O and A horizons (the topsoil), where shallow-rooted crops can now access them.

• Conclusion: The system effectively "pumps" nutrients from deep inaccessible layers up to the surface.

Step 2: Final Answer:
Nutrient pumping relies on tree roots reaching into the deep C horizon or subsoil layers.