Three Densities, One Argument: Population Pressure in Nahan District
Nahan district covers 4,200 km² with a population of 12.6 lakh. Of this, 2,100 km² is classified as cultivated land (arable), but only 1,700 km² is net sown in any single year; the balance is current fallow or orchards that fruit in alternate years. Agricultural workers number 2.1 lakh, about 68% of the workforce. Per capita food-grain availability fell from 168 kg to 141 kg between 2011 and 2021, and about 40% of the district's grain now arrives through the public distribution system. A proposal before the district board would convert 21,000 ha of pasture and scrub - used by roughly 9,000 households for grazing - into cultivation. Officials argue this will 'reduce population pressure on land'. A councillor replies that the district already cannot feed itself.
1. Calculate the arithmetic, physiological and agricultural densities for Nahan. Which one best answers the question 'is the district's land under pressure?' and why is arithmetic density the weakest of the three here?
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Calculations (state the denominator every time):
- Arithmetic density = 12,60,000 ÷ 4,200 = 300 persons/km²
- Physiological density = 12,60,000 ÷ 2,100 (arable) = 600 persons/km² of arable land
- Agricultural density = 2,10,000 agricultural workers ÷ 2,100 = 100 workers/km² of arable land
Which is relevant? Physiological density. Food pressure is mouths against the land that actually grows food, and 600 is double the headline 300 - which is why the district feels crowded despite an unremarkable arithmetic figure.
Why arithmetic density is weakest: half the district is not arable (scrub, forest, orchard, built-up), so spreading the population over 4,200 km² dilutes the pressure into land that feeds nobody. It also counts the urban population in the numerator, although that population does not live off district soil.
The agricultural density adds a different diagnosis: only 100 workers per km² of arable land is not high. The problem is therefore not too many farmers per hectare but low output per worker and per hectare - a productivity problem dressed up as a crowding problem. This distinction changes the prescription: land conversion would not fix it; yields would.
2. A student uses net sown area as the denominator and reports a physiological density of about 741, calling the 600 figure wrong. Judge the claim.
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Not wrong - defensible, provided the denominator is declared. Physiological density is population divided by arable land, and 'arable' can reasonably mean either:
- Net sown area (1,700 km²): 12,60,000 ÷ 1,700 ≈ 741 - pressure actually borne in a given year.
- Cultivated land including current fallow and orchards (2,100 km²): 600 - pressure against long-run potential.
Each captures something real. The 741 figure is the better one in a poor rainfall year, when fallow genuinely produces nothing. The 600 figure is better for comparing districts over time, because fallow area fluctuates with the monsoon and would make the ratio jump about for non-demographic reasons.
Where the student is actually wrong: if they then compare Nahan's 741 with another district's 600 computed on a different base. That is a comparison of two different measures and produces a false ranking - a common error in exam answers and in district handbooks.
Rule to apply: fix the denominator, print it in the map legend and in the table note, and use the same one for every unit being compared. Mixing bases is the error, not the choice of base.
3. Evaluate the proposal to convert 21,000 ha of pasture and scrub to cultivation. Recalculate the relevant density and judge whether the claimed relief is delivered.
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Recalculation. 21,000 ha = 210 km², so arable land rises to 2,310 km². New physiological density = 12,60,000 ÷ 2,310 ≈ 545 persons/km², down from 600 - a fall of roughly 9%.
Is that relief meaningful? Marginally, and only on paper. Three reasons to doubt it:
- The binding constraint is not hectare count. Per capita food-grain availability is already 141 kg and 40% of grain comes through the PDS. Output per hectare and purchasing power are the constraints; adding 9% more arable land to a district that already imports two-fifths of its grain does not change that.
- The land being converted is marginal. Scrub and pasture are typically the least productive land in the district; yields from them are unlikely to match the district average, so the real gain in output is smaller than the gain in area.
- Uncounted losses. About 9,000 households use that pasture for grazing. Their loss of fodder and common-property access is a real income loss that never appears in a density ratio, and it will hit the poorest households hardest.
Judgement: reject as framed. If any conversion proceeds, restrict it to already-degraded land, attach a yield package, and compensate fodder loss with planted fodder plots.
Better indicators of relief than density: per capita food-grain availability (target: reversal of the 168 → 141 kg decline) and the share of grain sourced through the PDS.