The physical frame: agro-climatic zones, agro-ecological regions and the monsoon

Detail

1. Why the physical frame matters: agriculture in India's economy

• Agriculture and allied activities means farming plus the work linked to it:
• crops and livestock
• apiculture (beekeeping)
• fisheries
• sericulture (raising silkworms for silk)

• fibre crops such as cotton and jute

• Share of the economy (NCERT, 2022-23): a little over 18% of GDP. It employs about 46% of workers.

• Newer official figures:
• Agriculture supports about 46.1% of the workforce. It gives about 16% of GDP (FY24, current prices) [8].
• Its share of GVA (gross value added: the value of goods and services produced, minus the cost of inputs) was 17.7% in FY24. Industry was 27.6% and services 54.7% [9].

• The gap is large. Close to half of all workers produce less than one-fifth of the output. This shows that farm productivity per worker is low.

• Women: more than 75% of rural women workers are in agriculture (NCERT, Class 7, 2025).

• What decides what grows where: four physical factors work together.
• Climate: temperature, rainfall and its timing
• Soil: type, depth, fertility and how well it holds water
• Water: rain, rivers, canals and groundwater
• Terrain: height above sea level, slope and plains versus hills

2. The seven climate types (NCERT, Class 7)

NCERT lists seven climate types, each with its own farming:

Climate type	Where in India (examples)	Typical farming
Alpine	High Himalaya: Ladakh, upper Himachal Pradesh, Sikkim	Short summer crops (barley, buckwheat); yak and sheep herding
Temperate	Kashmir valley, middle Himalaya	Apple, walnut, saffron; wheat
Subtropical	Northern plains: Punjab, Haryana, Uttar Pradesh	Wheat in winter; rice and sugarcane with irrigation
Arid	Western Rajasthan (Thar Desert)	Bajra, guar, moth beans; camel and sheep rearing
Tropical wet	Kerala, Konkan, North-East	Rice, spices, rubber, coconut, tea
Semi-arid	Interior Deccan: Maharashtra, Karnataka, Telangana	Jowar, pulses, cotton, oilseeds
Tropical	Most of peninsular and eastern India	Rice, sugarcane, many crops in a year

3. Agro-climatic zones of India (Planning Commission, 1988-89)

• Agro-climatic zone: a large area with a similar mix of climate, soil, terrain, water resources and vegetation. Farmers there can grow a similar set of crops in a similar season.

• The zones help plan what to grow, when to grow it and how.

• Origin:

• The Planning Commission set up 15 agro-climatic regions in 1988-89.
• It did this under the Agro-Climatic Regional Planning Project [2].

• NCERT Class 12 dates the start of agro-climatic planning to 1988.

• Aim: regionally balanced development. Each region's farming plan should match its natural resources, so no region falls far behind.

• Basis: terrain (physiography), soils, climate (mainly rainfall and temperature) and water resources.

The 15 agro-climatic regions (roughly north to south, then west):

No.	Region	Main area covered
1	Western Himalayan	Jammu & Kashmir, Ladakh, Himachal Pradesh, Uttarakhand
2	Eastern Himalayan	Sikkim, Darjeeling hills (West Bengal), Arunachal Pradesh, Assam and the North-Eastern hill states
3	Lower Gangetic Plains	West Bengal plains (the Ganga delta)
4	Middle Gangetic Plains	Bihar, eastern Uttar Pradesh
5	Upper Gangetic Plains	Western and central Uttar Pradesh
6	Trans-Gangetic Plains	Punjab, Haryana, Delhi, Ganganagar (north Rajasthan)
7	Eastern Plateau and Hills	Jharkhand (Chhotanagpur), Chhattisgarh, interior Odisha
8	Central Plateau and Hills	Madhya Pradesh, Bundelkhand, eastern Rajasthan
9	Western Plateau and Hills	Deccan Maharashtra (black-soil plateau)
10	Southern Plateau and Hills	Interior Karnataka, Telangana, Rayalaseema (Andhra Pradesh), interior Tamil Nadu
11	East Coast Plains and Hills	Coastal Odisha, Andhra Pradesh, Tamil Nadu and Puducherry
12	West Coast Plains and Ghats	Kerala, Goa, coastal Karnataka, Konkan (Maharashtra)
13	Gujarat Plains and Hills	Gujarat, including Kathiawar and Kachchh
14	Western Dry Region	Western Rajasthan (Thar Desert)
15	Islands	Andaman & Nicobar Islands (Bay of Bengal), Lakshadweep (Arabian Sea)

• How to remember the groups:
• 2 Himalayan regions
• 4 Gangetic plain regions (Lower, Middle, Upper, Trans), running east to west along the Ganga
• 4 plateau-and-hills regions (Eastern, Central, Western, Southern)
• 3 coastal or western regions (East Coast, West Coast, Gujarat)

• 1 dry region and 1 island region

• The Gangetic plain regions, east to west:

• Lower (West Bengal) → Middle (Bihar, eastern UP) → Upper (western UP) → Trans (Punjab–Haryana)
• Rainfall falls as you move west, so the western regions depend more on canals and tubewells.
• The Trans-Gangetic Plains (Punjab, Haryana) and Upper Gangetic Plains (western UP) became the core of the Green Revolution (from the mid-1960s). Canals, tubewells and high-yielding wheat and rice spread first in these regions.

4. Agro-ecological regions (ICAR–NBSS&LUP)

• Agro-ecological region: an area where the landform, soil, bioclimate and length of growing period are similar. It is a finer, more scientific division than the agro-climatic zone.

• Bioclimate means the climate as it affects plant life: whether the area is arid, semi-arid, sub-humid, humid or per-humid (very wet all year).

• Who made it: the National Bureau of Soil Survey and Land Use Planning (NBSS&LUP), Nagpur, which is part of the ICAR (Indian Council of Agricultural Research).

• Numbers: 20 agro-ecological regions, divided into 60 sub-regions.
• Four criteria: physiography (landform), soils, bioclimate and length of growing period (LGP) [3].
• Length of growing period (LGP): the number of days in a year when the soil has enough moisture and the temperature is right for crops to grow.
• Rainfall adds moisture to the soil.
• The soil stores some of it.
• Heat and plants draw moisture out (evapotranspiration).
• The LGP counts the days when moisture and temperature both stay good enough for crops.
• Short LGP (for example western Rajasthan): only one short crop, or pasture.

• Long LGP (for example Kerala, the North-East): two crops, or perennial crops such as rubber and spices.

• National Agricultural Research Project (NARP): a third, finer layer of 127 agro-climatic zones below the state level. Each state is split into several zones, and each zone has a research station that tests crops and practices for local conditions.

Comparing the three classifications:

Feature	Agro-climatic regions	Agro-ecological regions	NARP zones
Made by	Planning Commission (1988-89)	ICAR–NBSS&LUP	ICAR, under the NARP
Number	15	20 (60 sub-regions)	127
Basis	Terrain, soil, climate, water	Physiography, soil, bioclimate, LGP	Rainfall, soil, crops, terrain within each state
Scale	National, broad	National, scientific	Sub-state, local
Main use	Regional development planning	Land-use planning; matching crops to land	Local farm research and extension

5. The monsoon: the timetable of Indian farming

• Monsoon: a seasonal reversal of winds that brings a wet season and a dry season. How it works is covered in indian-climate-monsoon. This section deals with what it means for farming.
• The main facts:
• About 75% of India's annual rainfall comes in the south-west monsoon season (June–September) [5].
• The Long Period Average (LPA) of this season's rainfall for India as a whole is 87 cm (1971–2020 data) [4]. LPA is the long-term average that each year's rain is compared against.
• Only about 55% of the net sown area is irrigated. The rest is rainfed (it depends only on rain) [5].
• The IMD watches rainfall over the monsoon core zone closely, because this belt holds most of India's rainfed farmland [6].

South-west monsoon and kharif farming (north and central India)

• Season: June to September.
• How it drives farming:
• The rains wet the soil in June and July.
• Farmers sow kharif crops (rainy-season crops) such as rice, maize, jowar, bajra, cotton, soybean and groundnut.

• The crops grow through the wet months and are harvested in September–October.

• Where it matters most: the northern plains and the central plateau. This is the main crop season of north and central India.

North-east monsoon (east and south India)

• Season: October to December. It is also called the retreating or post-monsoon season.
• How it works:
• The winds reverse and blow from the north-east across the Bay of Bengal.
• They pick up moisture over the sea.

• They drop rain on the east coast, mainly Tamil Nadu, coastal Andhra Pradesh and south Kerala.

• Tamil Nadu: this is the state's chief rainy season. It gets 48% (443.3 mm) of its annual rainfall in October–December [7].

• Double monsoon: coastal Tamil Nadu and Kerala get rain from both monsoons.

Feature	South-west monsoon	North-east monsoon
Months	June–September	October–December
Wind source	Arabian Sea and Bay of Bengal branches	Bay of Bengal
Main areas	Most of India; heaviest on the Western Ghats and the North-East	East coast, especially Tamil Nadu; south Kerala
Share of rain	~75% of India's annual rainfall [5]	48% of Tamil Nadu's annual rainfall [7]
Farming role	Kharif sowing across the north and centre	Main crop season in Tamil Nadu; an extra crop in the south

North versus south: how farmers use the gap between rains

• South:
• Two monsoons fall a few months apart.
• The soil stays moist for longer, so the LGP is longer.

• Farmers can fit in an extra crop between the two monsoons.

• North:

• There is only one main rainy season.

• Winter (rabi) crops depend on groundwater (tubewells), canals, ponds and soil moisture left over from the monsoon.

• Rice all year: Tamil Nadu, West Bengal and Andhra Pradesh grow rice in more than one season. They have warm weather all year, plenty of water (two monsoons in Tamil Nadu, deltas and irrigation in West Bengal and Andhra Pradesh) and fertile delta soils.

6. Ancient knowledge: the Arthashastra's "good rainy season"

• The Arthashastra (Kautilya's ancient text on statecraft and economy) describes a "good rainy season":
• one-third of the rain falls at the start and the end of the season

• two-thirds falls in the middle

• Why this matters for crops:

• Some rain at the start lets farmers sow.
• Heavy rain in the middle helps the crop grow fast.

• Light rain at the end lets the crop ripen and be harvested without damage.

• Lesson: early Indian farmers understood that when it rains matters as much as how much it rains. This is why a delayed monsoon onset or a long break in the monsoon still harms farming today.

Prelims Hooks

• 15 agro-climatic regions: set up by the Planning Commission in 1988-89. 20 agro-ecological regions and 60 sub-regions: made by ICAR–NBSS&LUP. 127 zones: NARP. Exam traps often swap these numbers and bodies.
• NBSS&LUP's four criteria are physiography, soils, bioclimate and length of growing period (LGP). LGP is the number of days with enough soil moisture for crops [3].
• The four Gangetic plain regions from east to west: Lower → Middle → Upper → Trans-Gangetic. The Trans-Gangetic region is Punjab–Haryana, not Bihar.
• The Western Dry Region is western Rajasthan (Thar). The Western Plateau and Hills is Deccan Maharashtra. Do not mix them up.
• The Islands region covers both Andaman & Nicobar (Bay of Bengal) and Lakshadweep (Arabian Sea).
• LPA of south-west monsoon rainfall = 87 cm (1971–2020 base) [4]. The south-west monsoon brings about 75% of India's annual rainfall [5].
• Tamil Nadu gets 48% of its annual rainfall from the north-east monsoon (October–December) [7]. Coastal Tamil Nadu and Kerala get both monsoons.
• States growing rice year-round (NCERT): Tamil Nadu, West Bengal, Andhra Pradesh.
• Arthashastra's "good rainy season": 1/3 at the start and end, 2/3 in the middle.
• NCERT Class 7's seven climate types: alpine, temperate, subtropical, arid, tropical wet, semi-arid, tropical.

Mains Points

• Fitting crops to the land: agro-climatic and agro-ecological zoning lets planners match crops, water use and inputs to local conditions.
• It helps correct mismatches such as water-hungry rice and sugarcane in semi-arid Punjab, Haryana and Maharashtra.

• It guides crop diversification and watershed plans in rainfed plateau regions.

• Monsoon dependence is a structural risk: about 45% of the net sown area is still rainfed [5], and about 46.1% of the workforce depends on farming while it gives about 16% of GDP [8].

• So a late onset, a long break or uneven rain directly cuts rural income, food output and demand.

• Policy responses: expanding irrigation, crop insurance, IMD's monsoon core zone forecasts [6], and contingency crop plans made at district level.

• North–south contrast:

• The south's two monsoons and longer growing period allow two or three crops a year.
• The north's one rainy season pushes rabi farming onto groundwater and canals. This links the Green Revolution belt to today's groundwater depletion.

• A good GS-I answer on regional variation in agriculture can use this contrast.

• Old idea, current use: the Arthashastra's focus on how rain is spread through the season matches today's concern with intra-seasonal variability: the gaps and bursts of rain within one monsoon season. It is useful for GS-I questions on how traditional knowledge relates to climate adaptation.