IB Geography F.2.3 Diffusion in Agriculture and Disease Spread Notes

Diffusion Moves Innovations and Diseases Through Uneven Networks

1. Diffusion: is the spread of an idea, innovation, behaviour or disease between people and places over time.
2. Networks: speed diffusion where farms, markets, roads, migration routes and digital communication connect people.
3. Barriers: slow or redirect diffusion when distance, terrain, cost, regulation, conflict or social resistance interrupt those links.
4. The outcome: depends on both the thing spreading and the geography through which it moves.

Adoption or Acquisition Diffusion Spreads Through Uptake

1. Adoption: occurs when people take up an innovation such as a seed, irrigation method, vaccine or farming practice.
2. The innovation: does not need to leave its origin because each new user acquires or copies it.
3. Early adopters: often have better access to information, credit, land, water or technical support than later adopters.
4. Uneven uptake: can widen inequality when the first users gain higher yields or lower costs before others can participate.

Expansion Diffusion Spreads Outward from a Source

Nearby Contacts Carry the Pattern Across Space

1. Contagious expansion: moves through direct or near-direct contact, so incidence usually rises first around the source.
2. Hierarchical expansion: moves first between important people or large connected centres before reaching smaller places.
3. The source remains active: because the disease or innovation persists there while new locations are added.
4. Distance decay: often reduces the chance of contact, although transport and communication networks can weaken this effect.

Relocation Diffusion Moves with the Carrier

Migration and Trade Create New Sources

1. A carrier: moves from one place to another and brings a pathogen, crop, livestock breed or farming knowledge with them.
2. A new focus: can form far from the origin when air travel, shipping or migration bypasses nearby places.
3. Disease relocation: may be followed by expansion diffusion if local transmission begins after an imported case.
4. Agricultural relocation: has moved crops and livestock between continents through colonisation, trade and migration.

Punjab Shows Why Innovation Diffuses Unevenly

1. The innovation: was the Green Revolution package of high-yield wheat and rice varieties, irrigation, fertiliser, pesticides and mechanisation from the 1960s.
2. The place: Punjab adopted the package rapidly because many farms already had irrigation, market access and state support.
3. The barrier: farmers without credit, reliable water or enough land could not adopt the full input package as easily.
4. The spatial effect: higher yields concentrated first in well-connected and well-watered districts rather than spreading evenly across India.
5. The social effect: larger or better-capitalised farmers were more able to absorb the cost and risk of new seeds and inputs.

Physical Barriers Restrict Suitable Environments and Contact

1. Distance: raises transport costs and reduces repeated face-to-face contact.
2. Mountains, deserts and seas: interrupt movement unless roads, ports or air links overcome them.
3. Temperature and altitude: can block vector-borne disease where the vector or pathogen cannot survive or reproduce.
4. Seasonal conditions: can open and close routes of spread as rainfall, river flow, harvest work or migration changes.

Economic and Political Barriers Shape Access

1. Cost: slows agricultural adoption when seeds also require fertiliser, irrigation or machinery that farmers cannot afford.
2. Treatment access: affects disease diffusion when diagnosis, medicines or vaccines are unavailable or too expensive.
3. Borders and quarantine: can reduce movement but work only when surveillance identifies cases and enforcement reaches the relevant route.
4. Patent and trade rules: affect the price and availability of seeds, medicines and equipment.
5. Conflict: damages services, displaces people and restricts access for health or agricultural workers.

Social Barriers Can Slow or Redirect Uptake

1. Trust: affects whether people accept new crops, vaccines, spraying or public-health advice.
2. Language and literacy: shape whether technical information reaches users in a form they can act on.
3. Land tenure: discourages long-term investment where farmers do not expect to keep control of the land.
4. Cultural fit: matters because an innovation spreads more slowly if it conflicts with food preferences, labour roles or local knowledge.