Agriculture and food — core idea

· Guiding question: To what extent can the production of food be considered sustainable?
· Agriculture must balance food security, land limits, soil protection, biodiversity, greenhouse gas emissions, economic viability and environmental justice.
· Exam answers should evaluate environmental, social and economic sustainability, not just crop yield.

Land as a finite resource

· Land is finite, while the human population continues to grow and require feeding.
· About 70% of ice-free land is used for agriculture and forestry.
· Not all land is suitable for arable crops: land may be too steep, too dry, too nutrient-poor or have unsuitable soils.
· Land unsuitable for crops is often used for livestock production, but this can increase land pressure, overgrazing and soil degradation.
· High-scoring point: link land limits to carrying capacity, food security, soil quality and sustainable land-use planning.

Environmental justice and land rights

· Marginalized groups are more vulnerable when their needs are ignored in land-use decisions.
· Groups at risk include indigenous peoples, women farmers, low-caste groups, low-income communities and people in low-income countries.
· Loss of land rights can reduce access to food, water, livelihoods, culture and self-determination.
· Use a named example in essays, such as Maasai land rights in East Africa or indigenous communities displaced by commercial agriculture or conservation projects.
· Strong evaluation: land-use decisions may raise yields nationally but worsen inequality, malnutrition or environmental injustice locally.

Food production, waste and distribution

· World agriculture produces enough food to feed eight billion people, but food is not equitably distributed.
· At least one-third of food production is estimated to be lost or wasted, including post-harvest, storage and distribution losses.
· SDG 12.3 aims to halve per-capita global food waste at retail and consumer levels and reduce food losses along production and supply chains.
· Food security = physical and economic availability of food so all individuals can obtain a balanced diet for an active, healthy life.
· Famine is often caused by distribution problems, conflict, poverty and crop failure, not simply lack of global food biomass.
· Avoid the misconception that more food produced = food security; access, affordability, quality and distribution matter.

Types of agricultural systems

· Agricultural systems vary due to soil, climate, culture, technology, economics and market access.
· By output: arable, pastoral/livestock, mixed, monoculture, diverse.
· By purpose: commercial or subsistence; sedentary or nomadic.
· By inputs: intensive or extensive; irrigated or rain-fed; soil-based or hydroponic; organic or inorganic.
· Intensive systems usually have high inputs of fertilizer, pesticides, irrigation, energy, machinery and capital.
· Extensive systems use larger areas with lower inputs per unit area, but can still be unsustainable if they cause overgrazing, deforestation or habitat loss.
· Application skill: make a detailed comparison of one pair of named contrasting systems, evaluating environmental, social and economic impacts.

Traditional farming systems

· Nomadic pastoralism = livestock herding with movement between grazing areas; can be sustainable at low population density.
· Slash-and-burn agriculture = vegetation is cleared and burned; ash temporarily adds nutrients; land is later left to recover through fallowing.
· These systems can become less sustainable when population density increases, fallow periods shorten, or communities become fixed in one location.
· Traditional systems should be evaluated fairly: they may protect local knowledge and cultural identity, but may not always meet the food needs of large populations.

The Green Revolution

· Green Revolution = 1950s–1960s agricultural transformation using high-yielding crop varieties, improved irrigation, synthetic fertilizers and pesticides.
· Benefits: increased crop yields, improved food security, reduced pressure to convert some land, and helped some countries avoid famine.
· Criticisms: increased reliance on fossil fuels, synthetic nitrogen fertilizer, water, pesticides, commercial seeds and capital investment.
· It did not benefit all developing nations equally; poorer farmers may have lacked access to credit, irrigation, inputs and markets.
· Strong evaluation: the Green Revolution improved productivity, but its long-term sustainability is limited by soil degradation, water depletion, pollution, loss of genetic diversity and inequality.

Synthetic fertilizers and sustainable soil fertility

· Synthetic fertilizers maintain high yields in many intensive systems, but can reduce sustainability.
· Environmental risks include eutrophication, nitrate leaching, soil acidification, nitrous oxide emissions, fossil-fuel dependence and disruption of the nitrogen cycle.
· Sustainable alternatives include fallowing, organic manure, humanure, compost, green manure, herbal mixed leys, mycorrhizae, continuous cover forestry and agroforestry.
· Fallowing restores natural fertility by allowing vegetation and soil organisms to rebuild organic matter and nutrient cycling.
· Agroforestry combines trees with crops or livestock, improving soil protection, carbon storage, biodiversity and microclimate stability.

Soil conservation techniques

· Soil conservation has environmental, economic and sociocultural benefits because soil underpins food production, water cycling and livelihoods.
· Conservation from water erosion: terracing, contour ploughing, bunding, drainage systems, cover crops.
· Conservation from wind erosion: tree/hedge windbreaks and cover crops.
· Conservation of fertility: add lime, compost, green manure and other organic materials.
· Cultivation techniques: avoid marginal land, avoid overgrazing, avoid overcropping, use strip cultivation, mixed cropping, crop rotation, reduced tillage, agroforestry and reduced use of heavy machinery.
· Cover crops are especially useful because they reduce wind and water erosion and can be ploughed in as green compost.

The image shows fields farmed along contour lines, reducing the speed of surface run-off. This helps students visualize how contour farming reduces soil erosion and supports sustainable land management. Source

Diets, trophic levels and sustainability

· Humans are omnivorous, consuming fungi, plants, meat and fish.
· Diets based on lower trophic levels are generally more sustainable because less energy is lost through food chains.
· Food yield per unit land area is usually greater and lower cost for crops than for livestock.
· Plant-based diets can reduce land demand, feed conversion losses and greenhouse gas emissions, but sustainability still depends on farming method, supply chain and nutrition.
· Strong exam link: use second law of thermodynamics and energy transfer inefficiency to explain why eating producers is usually more efficient than eating higher trophic levels.

The diagram shows energy transfer between trophic levels and energy loss at each stage. It is useful for explaining why lower-trophic-level diets can support more people with less land and energy input. Source

Strategies for a sustainable food supply

· Current strategies aim to: reduce demand, reduce food waste, reduce greenhouse gas emissions and increase productivity without expanding agricultural land.
· Examples include plant-based meat substitutes, low-methane rice, reducing ruminant methane, reducing nitrogen loss, improving food shelf life, genetic modification to boost yields and solar-powered fertilizer production.
· Sustainable intensification = increasing output while reducing land conversion, pollution, water use, soil degradation and biodiversity loss.
· Evaluation: some technologies increase yield but may depend on fossil fuels, capital, patents, controlled supply chains or unequal access.

Food quality, malnutrition and global supply chains

· Food distribution patterns and food quality reflect the global food supply industry.
· Malnutrition includes both undernourishment and overnourishment.
· High biomass does not always mean high nutritional value; food may be low-quality, highly processed, energy-dense but nutrient-poor.
· Examples: Irish potato famine involved potato blight and dependency on one crop; East African famines can involve drought, conflict and distribution failure.
· Exam phrasing: food security is about availability, access, utilization/nutrition and stability over time.

Diet choices, food miles and environmental impact

· Sustainability of diets depends on supply chain efficiency, food miles, type of farming, farming techniques and societal diet changes.
· Food miles matter, but they are not the only factor; production method and food type can be more important.
· Year-round supply of out-of-season foods may increase energy use, transport, refrigeration and packaging.
· Cultural shifts such as eating more meat, less meat, vegetarianism or veganism can change land demand and emissions.
· The planetary health diet (PHD) links human health with environmental limits by emphasizing mostly plant-based foods while allowing limited animal products.
· Application skill: design a survey investigating food preferences and links to worldviews.

The diagram shows permaculture zoning, where land uses are arranged by intensity of care and distance from the home or centre. It supports the HL idea that alternative farming designs can improve efficiency, resilience and sustainability. Source

These images show crops grown in stacked or indoor systems using controlled conditions. They support the HL comparison between high productivity and the energy/capital costs of high-tech agriculture. Source