UPSC Prelims 2021 Q57: Water-Efficient Crops — Explained

Among the following, which one is the least water-efficient crop?

  1. Sugarcane
  2. Sunflower
  3. Pearl millet
  4. Red gram

Answer: (a) Sugarcane

Statement-wise explanation

  • a: correct — Sugarcane is the least water-efficient crop on this list. FAO puts its seasonal water requirement at 1,500–2,500 mm. A single crop stands in the field for about a year or longer, and its cane growth rises in direct proportion to the water it transpires. The Economic Survey 2021-22 names sugarcane, along with paddy and wheat, as the crops behind high groundwater stress in the regions that grow them.
  • b: incorrect — Sunflower is a short-duration oilseed. It matures in about 125–130 days, and FAO puts its seasonal water need at 600–1,000 mm. It is grown in rabi, kharif and summer seasons, often on residual soil moisture. It needs well under half of what sugarcane needs.
  • c: incorrect — Pearl millet (bajra) is the most drought-hardy major cereal. It is grown in arid and semi-arid areas that get roughly 150–700 mm of rain, such as western Rajasthan. FAO puts the water need of sorghum and millet at 450–650 mm over a 105–140-day season, so it is one of the most water-efficient crops here.
  • d: incorrect — Red gram (tur, arhar or pigeon pea) is a deep-rooted kharif pulse grown mostly without irrigation in semi-arid regions. It keeps growing after the monsoon ends by drawing on deep soil moisture, which is why it is valued as a drought-insurance crop. As a legume, it also fixes nitrogen in the soil.

How to eliminate

You need one fact here: sugarcane is the classic water-guzzling crop in India, along with paddy. With that, the question is quick. Pearl millet and red gram are textbook dryland crops, grown without irrigation in Rajasthan, the Deccan and other semi-arid belts, so you can drop both. That leaves sugarcane and sunflower. Sunflower is a three-to-four-month oilseed. Sugarcane is a crop that stays in the field for about a year and is grown mostly under irrigation in Maharashtra, Uttar Pradesh and Karnataka. A crop that grows for longer and depends on irrigation uses more water, so sugarcane is the least water-efficient. A useful rule for this family of questions: millets and pulses are the most water-efficient; oilseeds such as sunflower, mustard and groundnut come next; paddy, sugarcane and banana use the most. Water-policy campaigns such as the National Water Mission's 'Sahi Fasal' (2019) try to move farmers in water-stressed areas away from paddy and sugarcane.

Know more

Crop water requirement is the total water a crop loses to evapotranspiration over its growing season. It is usually given in millimetres of water depth. Two things push it up: how long the crop stays in the field, and how much leaf area it keeps transpiring. Water-use efficiency is the yield you get per unit of water used.

Crop Season length Seasonal water need (approx.) Typical water source
Sugarcane 10–18 months (plant + ratoon) 1,500–2,500 mm Canal / groundwater irrigation
Sunflower ~125–130 days 600–1,000 mm Rainfed or light irrigation
Pearl millet (bajra) ~105–140 days 450–650 mm Rainfed, arid/semi-arid
Red gram (tur) ~4–9 months Low; uses deep soil moisture Rainfed, semi-arid

Figures for sunflower and millet are from FAO's irrigation manual. The sugarcane figure is from FAO crop data.

Why this matters for India:

  • Paddy and sugarcane take a large share of irrigation water. Districts that grow them heavily, in Punjab, Haryana, western UP, Maharashtra and Tamil Nadu, show severe groundwater stress.
  • Policy responses include:
  • the Crop Diversification Programme under RKVY (since 2013-14), which shifts area from paddy to pulses, oilseeds and coarse cereals in the original Green Revolution states;
  • Per Drop More Crop (micro-irrigation under PMKSY);

  • the Sahi Fasal campaign of the National Water Mission (Nov 2019).

  • Drip irrigation in sugarcane can cut water use by roughly 20–60%. Its high cost has kept adoption low.

  • The ethanol blending programme has reopened this debate, because sugarcane-based ethanol carries a large water footprint. The government has encouraged maize and other grains as feedstocks.
  • Millets ('Shree Anna') and pulses are promoted because they are both nutritious and water-efficient. That is also why 2023 was declared the International Year of Millets.

NCERT Concepts to Revise

  • Bajra: One option is pearl millet; its rainfall needs and the regions where bajra grows help you judge how much water it uses.
  • Tur: Red gram appears under its other names, tur, arhar and pigeon pea; knowing it is a rainfed kharif pulse helps you place it.
  • Millets: Millets are the standard reference point for low-water crops in UPSC questions on cropping patterns and water use.

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