Four moth bean varieties bred by the ICAR-Central Arid Zone Research Institute (CAZRI), Jodhpur — CAZRI Moth-4, Moth-5, Moth-6 and Moth-7 — came through a 35-day dry spell in Kharif 2026, an El Niño year, in the hot arid districts of western Rajasthan.
Moth bean is among the most important pulse crops of that region, grown over close to 10 lakh hectares, and its productivity is low — around 350 kg per hectare. The reasons are climatic rather than agronomic: rainfall of only 150 to 250 mm, erratic and unreliable, dry spells of 20 to 30 days in a normal year, and very limited stored soil moisture.
The water balance, as it actually ran
The release gives an unusually complete record of the season, and reading it as a water-balance account is the most useful exercise a student can do with it.
| Period | What happened |
|---|---|
| Crop growth, 10 July to 2 September 2026 | Cumulative pan evaporation about 317 mm |
| Last significant rain, 2 August | 86 mm received |
| Rainfall ceased after 3 August | — |
| Dry spell, 3 August to 7 September | 35 days; cumulative pan evaporation about 180 mm; only three or four scattered showers of under 2.5 mm each |
Pan evaporation is the measurement that makes those numbers meaningful. A standard open pan of water is exposed in the field and the depth lost is recorded — a direct index of how hard the atmosphere is pulling moisture out of any wet surface, driven by temperature, wind, sunshine and dryness of air. A figure of 180 mm of evaporative demand across 35 days with essentially no rainfall is the crop's deficit stated plainly. The plant had to find that water somewhere or die.
Where it found it is the interesting part:
- Surface soil, 0 to 10 cm: moisture stood at about 15 to 16% by volume until 2 August, then fell to about 5 to 6% — effectively exhausted as a supply.
- Subsurface, 10 to 40 cm: declined more slowly, from about 23% to 16%, and continued to contribute to the crop's water requirement throughout.
So the crop survived by drawing on subsurface moisture after the surface layer dried out, which is exactly what a drought-adapted root system is for. Anyone revising soil geography should note how much of arid farming is about banking monsoon water in the subsoil and then spending it slowly.
The management practices listed were all directed at that banking operation: sowing timed to the monsoon's onset in July, a plant geometry of 45 × 10 cm, mechanical interculture at 20 days after sowing specifically for moisture conservation, mechanical weeding with manual spot weeding, and deliberate early canopy development. A closed canopy shades the soil surface and cuts direct evaporation; interculture breaks the surface crust and interrupts the capillary rise that would otherwise wick subsoil water to the air. Weeds are removed because in a 200-millimetre rainfall regime a weed is not a competitor for nutrients so much as a thief of water.
The soil these plants grew in
The experimental fields were poor by any standard, and the figures are a textbook description of arid desert soil:
- Organic carbon 0.13 to 0.18% — extremely low, because high temperatures oxidise organic matter as fast as it is added
- pH 7.9 to 8.1 — alkaline
- Available nitrogen 90 to 100 kg per hectare — low, following directly from the low organic carbon
- Available phosphorus 10 to 15 kg per hectare — low, and much of it locked up at alkaline pH
- Available potassium 250 to 260 kg per hectare — adequate to good, because it comes from weathering minerals rather than organic matter
That pattern — low organic carbon, alkaline, nitrogen- and phosphorus-deficient, potassium-sufficient, sandy — is the standard signature of the soils of the Thar. It is worth memorising as a set, because papers ask which nutrient Indian soils are generally deficient in, and the answer nationally is nitrogen and organic matter, with phosphorus close behind.
Why a legume, and why this legume
Moth bean (Vigna aconitifolia, also called mat bean, matki or dew bean) earns its place in this system three times over.
It fixes nitrogen. Like other legumes it hosts Rhizobium bacteria in root nodules, which convert atmospheric N₂ into a form the plant can use. In a soil holding 90 kilograms of available nitrogen per hectare, a crop that manufactures its own supply and leaves residue behind is doing fertility work that no cereal can. Students working through microbiology should be able to describe this as a symbiosis — the plant supplies carbohydrate and an oxygen-controlled environment, the bacterium supplies fixed nitrogen.
It covers the ground. Moth bean grows with a spreading, near-prostrate habit. The release credits early canopy development, soil binding and moisture retention in the rhizosphere with helping the crop survive the dry spell — and in the Thar, a creeping crop that binds sand is also erosion control against wind.
It is genuinely drought-hardy. Short duration and deep rooting let it complete its cycle on stored moisture, which is why it is grown where almost nothing else will yield.
The breeding objective named in the release is worth quoting precisely: developmental plasticity, enhanced stress resilience and yield potential. Plasticity here means the ability to adjust the timing and extent of growth and flowering to the water actually available — pausing under stress and resuming when moisture returns, rather than running a fixed schedule and failing. That is a subtler goal than raw yield, and it is the right one for an environment whose defining feature is unpredictability. Aspirants revising Indian agriculture should recognise this as the arid-zone counterpart of the Green Revolution's dwarfing and fertiliser-response traits: the trait you breed for depends on the constraint that binds.
El Niño, stated correctly
The season is described as an El Niño year, and the terminology repays precision.
ENSO — the El Niño-Southern Oscillation — is a coupled ocean-atmosphere oscillation in the tropical Pacific. El Niño is its warm phase: the central and eastern equatorial Pacific warms abnormally, the trade winds slacken, and the Walker circulation weakens, shifting the zone of deep convection eastward across the Pacific and away from the maritime continent. La Niña is the cool phase, with the opposite pattern. The atmospheric component is tracked by the Southern Oscillation Index, built on the pressure difference between Tahiti and Darwin.
For India the historical association is that El Niño years tend to bring a weaker southwest monsoon. Two qualifications belong in any good answer. The relationship is a tendency, not a rule — India has had normal monsoons in El Niño years. And a second mode, the Indian Ocean Dipole, can work with or against it: a positive IOD can partly offset an El Niño's drying influence on Indian rainfall. Candidates preparing the Indian monsoon should be able to say both things — the correlation and its limits — because the second half is what separates a memorised answer from an understood one.
Note also what the 2026 season actually looked like: not a failed monsoon, but a monsoon that arrived and then stopped. Rain in July established the crop; then five weeks of nothing during flowering and pod formation. Distribution within the season, not the seasonal total, is what determines whether a crop in this rainfall band survives.
From four varieties to ten thousand hectares
A variety that performs on a research farm changes nothing until its seed reaches farmers, and the release sets out that arithmetic.
Seed production is running over seven hectares at the CAZRI Research Farm against a SAATHI Portal-indented requirement of 23.32 quintals for 2026; in 2025 the indent across the four varieties was 63.2 quintals. SAATHI — Seed Authentication, Traceability and Holistic Inventory — is the national portal that tracks seed through the chain so that a farmer can verify what he is buying.
The multiplication factor is the striking figure: one quintal of breeder seed can yield around 1,000 to 1,400 quintals of certified seed, enough to plant about 10,000 hectares. India's seed chain runs nucleus seed → breeder seed → foundation seed → certified seed, with each generation multiplied and quality-checked before the next. Even at half the theoretical potential, four varieties multiplied through that chain can change what is sown across a substantial slice of arid Rajasthan — which is how a plant-breeding result eventually becomes a food-security outcome.
🔑 Revision block
The finding. Four CAZRI moth bean varieties — CAZRI Moth-4, 5, 6 and 7, released over the last three years — withstood a 35-day dry spell in Kharif 2026, an El Niño year, in arid western Rajasthan. Institute: ICAR-Central Arid Zone Research Institute, Jodhpur.
The crop. Moth bean (Vigna aconitifolia), grown on nearly 10 lakh hectares in western Rajasthan; productivity about 350 kg per hectare. Regional rainfall 150-250 mm, with normal dry spells of 20-30 days.
The season's water balance. Crop period 10 July to 2 September — pan evaporation about 317 mm. Last significant rain 2 August, 86 mm. Dry spell 3 August to 7 September, 35 days, pan evaporation about 180 mm, only three or four showers under 2.5 mm.
Soil moisture. Surface (0-10 cm) fell from 15-16% to 5-6%. Subsurface (10-40 cm) fell from about 23% to 16% and kept supplying the crop.
Management. Sowing with the July monsoon onset; 45 × 10 cm geometry; mechanical interculture at 20 days after sowing for moisture conservation; weed removal; early canopy closure to cut surface evaporation.
The soil signature. Organic carbon 0.13-0.18% · pH 7.9-8.1 · available N 90-100 kg/ha · available P 10-15 kg/ha · available K 250-260 kg/ha — the classic low-carbon, alkaline, N- and P-deficient, K-sufficient arid soil.
The biology. Legume; hosts Rhizobium in root nodules to fix atmospheric nitrogen — a symbiosis. Spreading habit binds soil and retains rhizosphere moisture. Breeding objective: developmental plasticity plus stress resilience.
ENSO. El Niño is the warm phase — anomalous warming of the central and eastern equatorial Pacific, weakened trades, weakened Walker circulation. La Niña is the cool phase. Tracked by the Southern Oscillation Index (Tahiti minus Darwin). El Niño tends to weaken the Indian monsoon; a positive Indian Ocean Dipole can partly offset it.
Seed chain. Nucleus → breeder → foundation → certified. One quintal of breeder seed yields about 1,000-1,400 quintals of certified seed, enough for roughly 10,000 hectares. Tracked on the SAATHI portal — 23.32 quintals indented for 2026, 63.2 quintals in 2025.
🎯 Practice MCQs
Q1. Moth bean is principally cultivated in: (a) The Konkan coast (b) Arid western Rajasthan (c) The Brahmaputra valley (d) The Malabar coast → (b) — on close to 10 lakh hectares.
Q2. CAZRI, the institute that bred these varieties, is located at: (a) Bikaner (b) Jodhpur (c) Jaipur (d) Hisar → (b) — the Central Arid Zone Research Institute.
Q3. El Niño refers to: (a) The cool phase of ENSO (b) Anomalous warming of the central and eastern equatorial Pacific (c) A monsoon trough over India (d) A cyclone in the Bay of Bengal → (b).
Q4. The Southern Oscillation Index is based on the pressure difference between: (a) Mumbai and Chennai (b) Tahiti and Darwin (c) Lima and Jakarta (d) Honolulu and Sydney → (b).
Q5. Pan evaporation measures: (a) Rainfall intensity (b) Atmospheric evaporative demand (c) Soil infiltration rate (d) Groundwater recharge → (b).
Q6. Nitrogen fixation in moth bean is carried out by: (a) Azotobacter in the soil (b) Rhizobium in root nodules (c) Mycorrhizal fungi (d) Blue-green algae on leaves → (b).
Q7. The duration of the dry spell that the CAZRI varieties withstood in Kharif 2026 was about: (a) 15 days (b) 21 days (c) 35 days (d) 50 days → (c) — 3 August to 7 September 2026.
Q8. The soils of the experimental fields had a pH of 7.9 to 8.1, meaning they were: (a) Strongly acidic (b) Neutral (c) Alkaline (d) Saline-sodic → (c).
Q9. Which nutrient was present at adequate levels in these arid soils? (a) Nitrogen (b) Phosphorus (c) Potassium (d) Organic carbon → (c) — potassium derives from weathering minerals rather than organic matter.
Q10. SAATHI, in the context of Indian agriculture, is a portal for: (a) Crop insurance claims (b) Seed authentication and traceability (c) Soil health cards (d) Farm machinery hiring → (b).
Q11. India's seed multiplication chain runs in the order: (a) Certified → foundation → breeder → nucleus (b) Nucleus → breeder → foundation → certified (c) Breeder → nucleus → certified → foundation (d) Foundation → nucleus → breeder → certified → (b).
Q12. Consider the following: 1. Every El Niño year necessarily produces a deficient southwest monsoon over India. 2. A positive Indian Ocean Dipole can partly offset El Niño's drying influence on Indian rainfall. (a) 1 only (b) 2 only (c) Both (d) Neither → (b) — the El Niño-monsoon link is a tendency, not a rule.
📋 How this gets asked (PYQ pattern)
Agriculture-and-climate items in NDA papers come from four directions. The ENSO item asks what El Niño is, which phase is which, or what the Southern Oscillation Index measures, and the trap is inverting El Niño and La Niña. The crop-region item matches a crop to its growing tract, where moth bean, bajra and guar all point to arid Rajasthan while jute points to the Ganga-Brahmaputra delta. The soil item asks which nutrient Indian soils generally lack, or what characterises arid soils — the answer being low organic carbon and nitrogen, with alkaline pH. The biology item asks which organism fixes nitrogen in legumes, rotating Rhizobium, Azotobacter, Nitrosomonas and Anabaena.
The fresh 2026 hook is the 35-day dry spell in an El Niño year and the four CAZRI moth bean varieties, likeliest as a statement pair on the ENSO phase and the legume nitrogen-fixation mechanism. We describe the recurring pattern here, not any exact past question.
Preparing for NDA? Climate and agriculture questions are easier to hold when attached to a real season, and this one carries the ENSO concept, the soil profile and the nitrogen cycle in a single story. Build the base with our NDA geography hub, follow the daily NDA current affairs, and prepare with our faculty in the upcoming Cavalier courses in Delhi.
✍️ Written by Col D.N. Sharma — Faculty at The Cavalier, mentoring NDA and SSB aspirants. Reviewed by the Cavalier Faculty Desk. The Cavalier, founded by ex-Army officers, has trained NDA/CDS/SSB aspirants since 2001 (Facebook · YouTube).
Source: PIB / Ministry of Agriculture & Farmers Welfare, 13 September 2026. ENSO mechanics, the Indian Ocean Dipole interaction, arid soil characteristics, legume nitrogen fixation and the seed multiplication chain cross-verified independently.