CSAT Solved Papers/ 2023/Q42
2023 CSAT — Q42
Passage
A global analysis of nitrogen use efficiency — a measure of the amount of nitrogen a plant takes in to grow versus what is left behind as pollution — says that using too much fertilizers will lead to increased pollution of waterways and the air. Currently, the global average for nitrogen use efficiency is approximately 0.4, meaning 40 per cent of the total nitrogen added to cropland goes into the harvested crop while 60 per cent is lost to the environment, says a study. More than half of the world’s population is nourished by food grown with fertilizers containing synthetic nitrogen, which is needed to produce high crop yields. Plants take the nitrogen they need to grow, and the excess is left in the ground, water and air. This results in significant emissions of nitrous oxide, a potent greenhouse and ozone depleting gas, and other forms of nitrogen pollution, including eutrophication of lakes and rivers and contamination of river water.
Which one of the following statements best reflects the most logical, rational and crucial message implied by the passage?
Thinking pathway
Locate. This asks for the author’s view: find the message the passage is committed to across its whole argument. The passage holds two facts in tension: synthetic nitrogen “is needed to produce high crop yields” and feeds “more than half of the world’s population”; but nitrogen use efficiency is only ~0.4, so 60% is “lost to the environment,” causing nitrous-oxide emissions, eutrophication and water contamination. The crucial message lives in the balance: nitrogen is essential for food, yet its inefficiency harms the environment.
Test (commitment test + scope-fit). (a) “enhanced efficiency of use of nitrogen is imperative for both food production and environment” honours both sides — it keeps the food-need and the environmental-harm, and improving efficiency is exactly what reconciles them (more crop, less loss). The author is committed to both halves. Test others: (b) “production… cannot be stopped” picks only the food side and over-states it; (c) “identify alternatives to nitrogen-hungry crops” is a specific remedy never prescribed; (d) “replace conventional agriculture with agroforestry/organic” is another specific prescription the passage doesn’t make.
Eliminate by anatomy. (b) is too strong and half right, half wrong — absolute on one side (“cannot be stopped”), dropping the environmental concern; (c) is a claim the passage never makes — crop-substitution is never proposed; (d) is a claim the passage never makes — the agroforestry/organic replacement is not in this passage. The transferable rule on author-view questions over a two-sided passage: the crucial message preserves both tensions; an option that amputates one side or jumps to a single remedy fails. Key: (a).
Evidence in the text
The passage states nitrogen use efficiency is low (≈0.4, so 60% is lost as pollution), yet synthetic nitrogen “is needed to produce high crop yields” and “more than half of the world’s population is nourished by food grown with” it, while excess causes nitrous-oxide emissions and eutrophication. The crucial message balances both sides — nitrogen is needed for food, but its inefficient use harms the environment — so improving nitrogen-use efficiency is imperative for BOTH food production and environment: exactly (a). (b) over-strengthens one side (“cannot be stopped”); (c)/(d) are specific remedies the passage never prescribes → (a).
Worked rationale
The passage balances need against harm: synthetic nitrogen is essential for yields and global nutrition, but at ~0.4 efficiency the 60% excess pollutes air and water. The crucial implied message is that we must use nitrogen more efficiently — serving both food production and the environment.
(a) captures exactly that two-sided imperative. (b) keeps only the food side and overstates it (“cannot be stopped”), ignoring the pollution argument. (c) and (d) are specific remedies (crop alternatives; replacing conventional agriculture) the passage never prescribes.
Answer: (a).
Why the other options miss
- B too strong for what the passage says: “production of synthetic nitrogen fertilizers cannot be stopped” absolutises one half of the tension and drops the environmental concern the passage gives equal weight.
- C a claim the passage never makes: “alternatives to crops that require excess of nitrogen should be identified” is a specific intervention the passage never proposes; it discusses efficiency, not crop substitution.
- D a claim the passage never makes: “replace conventional agriculture with agroforestry, agroecosystems and organic farming” is a wholesale remedy from elsewhere, not this passage’s measured message.
Specialist insight
This is a two-sided passage, and CSAT’s plants each grab one side or leap to a remedy. (b) keeps the food-security half and discards the environmental half; (c) and (d) substitute specific solutions for the passage’s actual point. The crucial message is the reconciling one — improve efficiency — because better nitrogen-use efficiency is precisely what serves both food production and the environment at once. Holding both halves and finding the option that does too is the move. (a).
The passage balances nitrogen's food-need against its pollution; (b) keeps only the food side — the crucial message is improving efficiency for both food and environment — (a).