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Difficulty: Very hardConservation of Natural Resources and Environmental Management

An environmental protection agency in a tropical agricultural region observed severe topsoil degradation due to surface runoff and a sharp decline in soil fertility. To achieve sustainable land management, ecologists recommended integrating a biological conservation method that replenishes soil nitrates naturally alongside a physical conservation technique that retards water runoff velocity on hilly terrain. Which of the following combinations of practices best satisfies both requirements?

  1. Cultivating leguminous cover crops and constructing contour bunds across slopesAnswer
  2. B
    Applying heavy inorganic synthetic fertilizers and practicing clean weeding on exposed slopes
  3. C
    Burning crop residues post-harvest and establishing cereal monocultures parallel to the slope
  4. D
    Practicing deep longitudinal plowing downhill and removing natural tree canopies

Answer

Cultivating leguminous cover crops and constructing contour bunds across slopes
The combination of cultivating leguminous cover crops and constructing contour bunds addresses both critical aspects of sustainable land conservation. Legumes work symbiotically with nitrogen-fixing bacteria to enrich the soil with organic nitrates, while contour bunds physically alter the topography to slow surface runoff and reduce topsoil erosion on sloped agricultural lands.

Step-by-Step Solution

1
Identify the biological requirement for natural nitrate replenishment
Leguminous plants form symbiotic associations with nitrogen-fixing bacteria (Rhizobium) in their root nodules, converting atmospheric nitrogen into nitrates naturally.
This avoids reliance on synthetic fertilizers, preventing eutrophication and restoring soil fertility biologically.
2
Identify the physical engineering requirement for erosion control on slopes
Contour bunds (embankments constructed along lines of equal elevation) reduce slope length and slow down runoff velocity.
Lowering runoff speed prevents sheet and rill erosion while promoting water infiltration into the soil profile.
3
Synthesize the combined practice
Combining leguminous cover crops with contour bunding simultaneously addresses biological soil restoration and physical runoff control.
Integrated natural resource management requires multi-faceted biological and physical interventions.

Key Concept

Integrated Soil Conservation and Biological Nitrogen Fixation
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Topics

Conservation of Natural Resources and Environmental Management

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