Origins and diffusion of agriculture
Agriculture means deliberately growing plants and raising animals for food, fibre or other uses. Before it, people were hunter-gatherers.
The First Agricultural Revolution (Neolithic, about 10,000–12,000 years ago) began independently in several hearths: the Fertile Crescent of Southwest Asia (wheat, barley, goats), China's river valleys (rice, millet), Mesoamerica (maize, beans, squash), the Andes (potato), West Africa (sorghum, yams) and the Indus region (cotton, sesame). People chose seeds from the plants they liked best; over generations this domestication made crops larger and easier to harvest.
Farming then spread by diffusion: people migrated with seeds and animals, and neighbours copied them. Later, the Columbian Exchange after 1492 moved crops across oceans: maize, potato and chilli to Asia and Africa; wheat, rice and cattle to the Americas.
Cultivated plants
Main groups: cereals (rice, wheat, maize), pulses (lentils, beans), oil seeds, vegetables and fruits, fibres (cotton, jute), beverages (tea, coffee) and spices.
The Second Agricultural Revolution and the Green Revolution
The Second Agricultural Revolution (about 1700–1900, starting in Western Europe) went with the Industrial Revolution. Changes: the seed drill and iron plough, the four-field crop rotation, selective breeding of animals, enclosure of land, then steam and later petrol machines. Results: more food per worker, so more people moved to cities to work in factories.
The Green Revolution (Third Agricultural Revolution, from the 1960s) spread high-yield varieties (HYV) of wheat and rice together with irrigation, chemical fertiliser, pesticides and machines. Mexico, India (Punjab, Haryana) and the Philippines saw yields rise two to three times and famines fall. Downsides: heavy groundwater use, soil and water pollution, loss of local seed varieties, and benefits going mainly to farmers who could afford inputs.
Today, biotechnology (GM crops), precision farming with GPS and drones, and organic farming continue these changes.
Types of farming and agricultural production regions
- Subsistence: grown mainly for the family; small plots, hand tools, family labour. Examples: shifting cultivation in tropical forests, intensive wet rice in monsoon Asia, nomadic herding in dry lands.
- Commercial: grown for sale; large farms, machines, hired labour. Examples: grain farming in temperate plains, plantations (tea, coffee, rubber, oil palm), mixed crop and livestock farming, dairying, market gardening, ranching.
- Intensive: much labour or capital on a small area, high output per hectare.
- Extensive: little input over a large area, low output per hectare (ranching, shifting cultivation).
Climate, soil, relief, water, markets and culture decide which type is found where, forming broad agricultural production regions. Field patterns also differ: long-lot, square survey grids and irregular plots shape how villages are laid out (clustered, dispersed or linear settlement).
The von Thünen model
In 1826 Johann Heinrich von Thünen imagined one market town in a flat, even plain with no rivers or roads, where farmers carry goods to market and pay transport costs by distance. He asked: which crop pays most at each distance?
Land rent (profit per hectare) = yield × (market price − production cost − transport cost × distance). Crops with high transport cost or that spoil quickly lose profit fast with distance, so they win near town. This gives four rings:
- Market gardening and dairy (perishable, heavy).
- Forest/wood (heavy fuel and building material).
- Field crops and grain (keep well, lighter per value).
- Ranching and grazing (animals walk to market).
Real landscapes are not perfect rings because of rivers, roads, relief and modern refrigerated transport, but the idea of distance decay still explains why milk and vegetables come from close to cities.
The global system, consequences and challenges of agriculture
Food today moves in a global system: commodity chains link farmers to traders, processors, supermarkets and consumers across continents. Large agribusiness companies control seeds, fertiliser and processing. Many countries export cash crops and import staple foods.
Consequences
- Positive: more food, cheaper food, rural jobs, export earnings.
- Negative: deforestation, soil erosion and salinisation, water pollution (fertiliser runoff), loss of biodiversity, desertification from overgrazing, methane from rice and cattle.
Challenges
Feeding about 8 billion people, climate change, water shortages, food deserts in cities, food waste, debate over GM crops, fair trade and local food. Sustainable methods include crop rotation, terracing, drip irrigation, agroforestry and conservation tillage.
Women in agriculture
Women do a large share of farm work worldwide, especially in South Asia and Africa (planting, weeding, harvesting, animal care, processing), but often own little land and get less credit, training and machines. Giving women equal access to land, loans and training raises farm output and family nutrition.
Try it: be von Thünen
In the last 3D step, find the distances where the winning land use changes (about 3, 6 and 11 km). Why does dairy win near town but lose quickly? At home: check the labels on fruit, vegetables, grain and packaged meat in your kitchen. Which travelled the furthest? Does it match the rings?
Key formulas and definitions
- Land rent = yield × (price − cost − transport rate × distance)
- Von Thünen rings: dairy/vegetables → forest → grain → ranching
- First Revolution: domestication (~10,000 years ago)
- Second Revolution: tools, rotation, machines (~1700–1900)
- Green Revolution: HYV seeds + irrigation + fertiliser (1960s–)
- Subsistence vs commercial; intensive vs extensive
Worked examples
1. A vegetable crop gives 10 t/ha, sells at 30 per t, costs 10 per t to grow and 4 per t per km to transport. Find the land rent at 2 km.
Rent = 10 × (30 − 10 − 4 × 2) = 10 × (30 − 10 − 8) = 10 × 12 = 120 per hectare.
2. Using the same vegetable crop, at what distance does land rent become zero?
Set 30 − 10 − 4d = 0 → 4d = 20 → d = 5 km. Beyond 5 km growing vegetables makes a loss, so another land use takes over.
3. A district's wheat yield rose from 1.5 t/ha to 4 t/ha after the Green Revolution. By what factor did it increase, and name two costs of this change.
Factor = 4 ÷ 1.5 ≈ 2.7 times. Costs: groundwater levels fell because of heavy irrigation, and soils and water were polluted by fertiliser and pesticides (also: loss of local seed varieties).
Common mistakes
- Thinking farming began in one place and spread from there. It started separately in several hearths.
- Confusing intensive with commercial. A small subsistence rice farm can be very intensive.
- Saying von Thünen's rings are about soil fertility. The model assumes equal soil; distance and transport cost decide.
- Calling the Green Revolution only a success. It raised yields but also caused water, soil and inequality problems.