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UPSC CSE CSAT 2021 · Question 12 · Reading comprehension

Consider the following: Cover crops

Passage—2

At the heart of agroecology is the idea that agroecosystems should mimic the biodiversity levels and functioning of natural ecosystems. Such agricultural mimics, like their natural models, can be productive, pest-resistant, nutrient conserving, and resilient to shocks and stresses. In ecosystems there is no ‘waste’, nutrients are recycled indefinitely. Agroecology aims at closing nutrient loops, i.e., returning all nutrients that come out of the soil back to the soil such as through application of farmyard manure. It also harnesses natural processes to control pests and build soil fertility i.e., through intercropping. Agroecological practices include integrating trees with livestock and crops.

CSAT 2021 · Q12

Reading comprehension Medium

Consider the following:

  1. 1.Cover crops
  2. 2.Fertigation
  3. 3.Hydroponics
  4. 4.Mixed farming
  5. 5.Polyculture
  6. 6.Vertical farming

Which of the above farming practices can be compatible with agroecology, as implied by the passage?

Answer & explanation

Answer: (a) 1, 4 and 5 only

Agroecology, as described, copies natural ecosystems: high biodiversity, nutrients returned to the soil, natural pest control and trees, crops and livestock integrated. Cover crops, mixed farming and polyculture fit these principles; fertigation, hydroponics and vertical farming depend on external inputs or soil-free, controlled systems.

  • ✓ 1. Cover crops protect the soil and return nutrients to it — 'closing nutrient loops' and building soil fertility.
  • ✗ 2. Fertigation feeds soluble fertiliser through irrigation water — an external input rather than recycling nutrients back to the soil.
  • ✗ 3. Hydroponics grows plants without soil in nutrient solutions, so there is no soil nutrient loop or natural ecosystem to mimic.
  • ✓ 4. Mixed farming combines crops with livestock, matching 'integrating trees with livestock and crops', and its manure returns nutrients to the soil.
  • ✓ 5. Growing many crops together, like intercropping, mimics natural biodiversity and uses natural pest control.
  • ✗ 6. Vertical farming is a controlled, often soil-less indoor system — far from mimicking the biodiversity and functioning of natural ecosystems.

Remember · Match each practice against the passage's defining principles (biodiversity, soil nutrient loops, integration); reject high-input or soil-free systems.

Question and answer: UPSC's official GS Paper II (2021, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·

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