AP Human Geography Unit 5 Review: Agriculture and Rural Land-Use

Agricultural practices are shaped by climate and physical environment. Mediterranean climates support olives, grapes, and citrus. Tropical climates support plantation crops like rubber and bananas. The key distinction for the exam is intensive versus extensive agriculture: intensive practices apply high inputs of labor or capital to smaller areas, while extensive practices spread low inputs across large areas.

• Intensive practices: Market gardening, plantation agriculture, and mixed crop-livestock systems all use high labor or capital inputs per unit of land.
• Extensive practices: Shifting cultivation, nomadic herding, and ranching use low inputs spread over large land areas, often in lower-density regions.
• Market gardening: Also called truck farming, this intensive practice produces fruits and vegetables for nearby urban markets, often in peri-urban zones.
• Shifting cultivation: Farmers clear land using slash-and-burn, grow crops for a few seasons, then move on, allowing the land to regenerate; common in tropical rainforest regions.
• Pastoral nomadism: Herders move livestock seasonally across arid and semi-arid regions in search of pasture and water, a form of extensive subsistence agriculture.

How land is divided and how settlements are arranged across rural landscapes reflects both agricultural practice and historical surveying systems. The three settlement patterns and three survey methods are directly testable on the AP exam.

• Clustered settlement: Buildings grouped tightly together, often around a village center; common where defense or shared resources mattered.
• Dispersed settlement: Farmsteads scattered across the landscape with no central nucleus; typical of the American Midwest under township and range.
• Linear settlement: Homes and farms arranged along a road, river, or coastline; associated with the long-lot system in French colonial areas.
• Township and range: The US Public Land Survey System divides land into six-mile-square townships and one-mile sections, creating the grid visible from the air across the Midwest.
• Long lot: Narrow parcels extending back from a river or road, giving each owner water or road access; used in French colonial Louisiana and Quebec.

Agriculture was independently invented in multiple hearths. The Fertile Crescent is the most tested, but the Indus River Valley, Southeast Asia, and Mesoamerica are also required. From these hearths, crops and animals spread through diffusion, most dramatically through the Columbian Exchange after 1492.

• Fertile Crescent: The earliest and most cited hearth, where wheat, barley, sheep, and goats were first domesticated in the Middle East.
• Mesoamerica: Hearth for maize, squash, and common beans (the Three Sisters), as well as the domestication of turkeys.
• Columbian Exchange: The transfer of crops, animals, and diseases between the Americas and the Old World after 1492; introduced potatoes and maize to Europe and wheat and cattle to the Americas.
• Agricultural revolutions: Waves of change, from the Neolithic Revolution onward, that spread farming practices and transformed human societies.
• Indus River Valley: Hearth for zebu cattle, chickpea, and sesame domestication in South Asia.

Two major technological waves transformed food production after the first domestication era. The Second Agricultural Revolution began in Britain and enabled industrialization. The Green Revolution spread high-yield technology to the developing world in the mid-20th century, with both positive and negative results.

• Second Agricultural Revolution: British-origin changes including Jethro Tull's seed drill, the Norfolk four-course crop rotation, selective breeding, and enclosure, which raised yields and freed rural labor for factories.
• Enclosure movement: The privatization of common lands in Britain that pushed rural workers off the land and into urban factory work, accelerating industrialization.
• High-yield variety (HYV) seeds: Semi-dwarf wheat and IR8 rice developed during the Green Revolution that dramatically increased grain output, especially in India and Mexico.
• Green Revolution consequences: Positive: increased food supply, reduced famine risk. Negative: groundwater depletion, soil salinization, agrobiodiversity loss, and smallholder debt.
• Mechanization: The use of machines such as combine harvesters and tractors to replace hand labor, increasing output per worker in both revolutions.

Economic forces determine whether farming is subsistence or commercial and whether it is intensive or extensive. Large-scale agribusiness is replacing family farms, and complex commodity chains now connect producers and consumers across the globe. Technology has raised economies of scale and the carrying capacity of the land.

• Subsistence vs. commercial agriculture: Subsistence farming produces food for the farmer's household; commercial agriculture produces for market sale, often as monoculture.
• Bid-rent theory: Land costs decrease with distance from the market, so intensive farming clusters near cities where land is expensive and extensive farming occupies cheaper distant land.
• Monoculture: Growing a single crop species over a large area, common in commercial agriculture; increases efficiency but raises vulnerability to pests and reduces biodiversity.
• Commodity chains: The full sequence of production, processing, distribution, and consumption that links a farm to a consumer, often spanning multiple countries.
• Economies of scale: As farm operations grow larger, the cost per unit of output falls; this drives consolidation of small family farms into large corporate agribusiness operations.

Johann Heinrich von Thunen's model explains rural land use by showing that transportation costs and distance from the market determine what farmers grow. The model assumes an isolated state with uniform soil and no geographic barriers. Closer rings support intensive, perishable, or heavy products; outer rings support extensive, durable crops and livestock grazing.

• Concentric rings: Von Thunen arranged land use in rings outward from the market: market gardening and dairying, then timber, then grain, then livestock grazing at the outermost ring.
• Transportation cost logic: Perishable or heavy goods must be produced close to market to minimize transport costs; durable or lightweight goods can be produced farther away.
• Bid-rent curve: Each land use type has a different rate at which it can pay rent as distance from market increases; the steepest curve wins the land closest to the center.
• Limitations: Real-world geography, refrigeration, highways, and specialty farming regions mean actual land use does not always match the model's concentric rings.
• Scale application: The model can be applied at local, regional, and even global scales to explain why certain agricultural regions specialize in particular products.

Food is now part of a global supply chain. Some countries depend heavily on one or two export commodities, making them economically vulnerable. Political relationships, infrastructure quality, and trade patterns all shape how food moves from producer to consumer across the world.

• Global food supply chain: The network connecting agricultural producers, processors, distributors, and consumers across multiple countries and regions.
• Export commodity dependence: Countries like Colombia (coffee) or Ivory Coast (cocoa) rely heavily on a single crop for export revenue, creating economic vulnerability to price swings.
• Political relationships and trade: Tariffs, trade agreements, and political conflicts affect which countries can access global food markets and at what cost.
• Infrastructure: Cold chain logistics, grain elevators, port facilities, and road networks determine whether agricultural products can reach global markets efficiently.
• Global interdependence: Producing and consuming regions depend on each other; disruptions in one region, such as drought in a major wheat exporter, affect food prices worldwide.

Agricultural practices reshape both the physical landscape and human society. Environmental consequences include pollution, desertification, soil salinization, deforestation, and land cover change. Societal consequences include dietary shifts, changing roles of women in food production, and the transformation of agriculture into a profit-driven economic sector.

• Soil salinization: Irrigation in arid regions deposits salts in the soil over time, eventually making land infertile; a major problem in parts of Central Asia and the American West.
• Desertification: Overgrazing and poor land management degrade vegetation cover, turning productive land into desert-like conditions, especially in the Sahel.
• Eutrophication: Fertilizer runoff carries excess nitrogen and phosphorus into waterways, triggering algal blooms that deplete oxygen and create dead zones, such as in the Gulf of Mexico.
• Deforestation: Clearing forests for cattle ranching and soy cultivation, especially in the Amazon, causes habitat loss, carbon release, and biodiversity decline.
• Women's roles in agriculture: In many subsistence systems, women perform the majority of planting, weeding, and harvesting, but often lack formal land tenure rights or access to credit and extension services.

Modern agriculture faces debates over biotechnology and GMOs, food access, distribution failures, and the economics of large-scale production. Food movements like community-supported agriculture, organic farming, fair trade, and local food networks have emerged as responses. Government policies and economies of scale shape what gets grown and who can afford to eat it.

• GMOs and biotechnology: Genetically modified organisms can increase yields and pest resistance but raise debates about biodiversity loss, corporate control of seeds, and long-term ecological effects.
• Food deserts: Areas, often low-income urban neighborhoods, where residents lack convenient access to affordable, nutritious food due to the absence of grocery stores.
• Food insecurity: The condition of lacking consistent access to enough safe and nutritious food; caused by poverty, distribution failures, adverse weather, and land lost to suburbanization.
• Community-supported agriculture (CSA): A model where consumers buy shares of a farm's harvest in advance, supporting local farmers and receiving fresh produce directly.
• Fair trade: A certification and trade movement that ensures farmers in developing countries receive fair wages and better working conditions for export crops like coffee and cocoa.

Women perform a large share of agricultural labor globally, but their roles vary significantly by region, crop type, and cultural context. In many subsistence systems, women handle planting and post-harvest processing. In commercial systems, women often work as plantation laborers. Access to land tenure, credit, and extension services differs widely and affects productivity and development outcomes.

• Geographic variation in female roles: In sub-Saharan Africa, women produce the majority of food crops. In South and Southeast Asia, women handle rice transplanting. In commercial plantation systems, women often fill seasonal labor roles.
• Land tenure and access: In many regions, women cannot legally own land or inherit it, limiting their ability to invest in farm improvements or access credit.
• Post-harvest processing: Women frequently handle processing, storage, and marketing of agricultural products, roles that are often unpaid or undercounted in economic statistics.
• Microcredit and cooperatives: Programs that provide small loans or organize women into cooperatives have improved agricultural productivity and income in parts of South Asia and Africa.
• Mechanization and gender: When mechanization replaces tasks traditionally done by women, it can displace female labor without providing alternative income, worsening gender inequality.