In the early 1960s, wheat farmers across Punjab, India were harvesting roughly 1.3 tonnes per hectare, a yield that had barely moved in generations. By the 1970s it had roughly doubled. Today it sits at around 5 tonnes per hectare, nearly four times the 1965 figure. This is one of the fastest jumps in food production in human history: the Green Revolution.
Before you see what made it possible, what do you think was the single biggest driver of that leap in yield?
- Wheat yield: about 1.3 t/ha (1965) → about 2.5 t/ha (1970) → about 5.1 t/ha (2024/25)
- Net irrigated share of cropped area: 49% (1950-51) → 81% (1980-81)
- Synthetic (NPK) fertilizer use: roughly a sixfold increase between 1971 and 2001
- Groundwater table decline accelerating: about 18 cm/year (1982-87) → about 75 cm/year (2002-06)
- 79% of Punjab's groundwater blocks were classified "over-exploited" in a 2020 government assessment
Figures from Indian government agricultural statistics (ICAR), Punjab land-use research, and the Central Ground Water Board's 2020 block-wise assessment. Full sources in this tab's citation list.
Land is finite
Only so much of Earth's surface can grow crops or support grazing livestock, and the population feeding itself from that fixed area keeps growing. About 70% of the world's ice-free land is already used for agriculture and forestry combined. Not all of that land is equally useful for growing food directly: some is too steep to cultivate safely, some soils are too shallow or too nutrient-poor to support arable crops (see subtopic 5.1 for what makes a soil productive in the first place). Land like this is far more often used for livestock grazing, which tolerates poorer, steeper, or drier land, than for plowing and planting.
A hillside is too steep and its soil too thin for a tractor or a plow to work safely. What is it most likely to be used for instead?
Livestock can graze land that is too steep, too dry, or too nutrient-poor for a plow and a crop to succeed on, which is exactly why grazing and arable farming end up occupying different land, not competing for the same land.
Land-use decisions and marginalized groups
Land-use decisions are rarely made by the people most affected by them. When land is reallocated, for conservation, for commercial agriculture, or for infrastructure, the groups with the least political and economic power are the most likely to be displaced and the least likely to be compensated. Indigenous peoples, low-caste communities, women farmers, and people in low-income countries are consistently the most vulnerable when their land rights are not formally recognized or not taken into account.
Named example: the Ogiek people of Kenya's Mau Forest
The Ogiek, an Indigenous hunter-gatherer community numbering roughly 20,000 to 35,000 people, have lived in Kenya's Mau Forest for generations. Starting in 2009, Kenya's government ordered repeated evictions of Ogiek communities from the forest, justified on conservation grounds. In 2017, the African Court on Human and Peoples' Rights ruled that Kenya had violated the Ogiek's rights to land, natural resources, culture, and non-discrimination. A 2022 reparations judgment ordered Kenya to pay damages, restore the Ogiek's ancestral land, and formally recognize them as Indigenous. As of the following year, Kenya had not fully complied: further evictions and home demolitions were reported in the Mau Forest even after the ruling.
If a question asks for a named example of marginalized people deprived of land rights, name the group, the location, and the specific mechanism of harm (eviction, lack of legal recognition, exclusion from the decision). "Indigenous peoples are often marginalized" on its own is too vague to earn an Identify or Outline mark; "the Ogiek of Kenya's Mau Forest were evicted from their ancestral land for conservation purposes without their land rights being recognized" is specific enough.
Enough food, unequal distribution
World agriculture already produces enough food to feed all eight billion people alive today. The shortfall people experience is not a production problem, it is a distribution problem. At least one-third of the food produced globally is lost or wasted: in the field, in storage, in transport, or after it reaches a household. UN Sustainable Development Goal target 12.3 commits countries to halving per-capita food waste at the retail and consumer level, and reducing losses along production and supply chains, by 2030.
It is a common misconception that global hunger means the world is not growing enough food. Enough calories are produced globally to feed everyone; the food insecurity that exists is overwhelmingly a problem of distribution, affordability, and waste, not of total global production falling short.
How agricultural systems vary
Agricultural systems differ across the world largely because soils and climates differ (subtopic 5.1 covers what makes a soil more or less productive for a given crop). On top of that physical variation, farmers make different choices for economic, social, and environmental reasons. Agricultural systems can be classified along several independent dimensions at once: what the farm produces (arable crops, pastoral livestock, a mix, a single crop grown as a monoculture, or a diverse range of crops), why the farmer is farming (to sell commercially or to feed their own household, in one settled location or moving seasonally), and what inputs the system depends on (intensive or extensive use of land and labor, irrigated or rain-fed water, soil-based or hydroponic growing, organic or inorganic inputs).
Sort each farm description into commercial or subsistence agriculture.
Traditional low-intensity systems
Nomadic pastoralism (moving livestock seasonally between grazing areas) and slash-and-burn agriculture (clearing a plot by burning vegetation, farming it for a few seasons, then moving on and letting it regrow) are traditional techniques that sustained low-density human populations in many parts of the world for centuries without degrading the land.
Slash-and-burn is not inherently unsustainable. At low population densities with sufficiently long fallow periods (the years a plot is left to regrow before being farmed again), the land fully recovers between uses and the system can continue indefinitely. It becomes unsustainable specifically when population density rises or communities settle permanently, both of which shorten the fallow period below what the land needs to recover.
- Punjab wheat yield, fertilizer use, and irrigation figures: Indian Council of Agricultural Research (ICAR) statistics and Punjab agricultural land-use research.
- Punjab groundwater decline and "over-exploited" block classification: Central Ground Water Board (CGWB) 2020 block-wise assessment, reported via Mongabay-India and Scroll.in.
- Global land use for agriculture and forestry (~70% of ice-free land): FAO/Our World in Data land-use analysis.
- Ogiek people of Kenya's Mau Forest: African Court on Human and Peoples' Rights, African Commission on Human and Peoples' Rights v. Republic of Kenya, merits judgment 26 May 2017, reparations judgment 23 June 2022; reporting by Minority Rights Group and OHCHR.
- Global food waste and SDG target 12.3: UN Sustainable Development Goals framework; UNEP Food Waste Index Report 2024.
- IB Environmental Systems and Societies Guide, first assessment 2026, Topic 5, Subtopic 5.2, statements 5.2.1-5.2.6.
The Green Revolution's consequences
The Green Revolution (also called the Third Agricultural Revolution) combined high-yielding crop varieties with expanded irrigation, synthetic fertilizer, and pesticides to raise food production sharply from the 1950s and 1960s onward. In Punjab, as the hook on the previous tab showed, this quadrupled wheat yields within a few decades and helped prevent famine for a rapidly growing population. It also carried costs. Improved productivity depended on fixing nitrogen into synthetic fertilizer, a process that is fossil-fuel dependent, so intensification also intensified fossil-fuel demand. Benefits were also uneven: farmers who could afford the seeds, fertilizer, and irrigation infrastructure gained the most, while poorer farmers and regions that lacked irrigation access were often left behind, and the Green Revolution did not occur in all developing nations to the same extent.
Punjab's groundwater table has been declining at an accelerating rate, from about 18 cm per year in the 1980s to about 75 cm per year by the 2000s. What is the most direct cause of this trend?
Net irrigated area in Punjab rose from 49% to 81% of cropped land between 1950 and 1980, much of it from tube wells pumping groundwater. When water is extracted faster than it is naturally recharged, the water table falls, and by 2020 about 79% of Punjab's groundwater blocks were classified as over-exploited.
Punjab's falling water table is the same steady-state failure taught in Topic 4: a store, here a groundwater aquifer, stays in balance only while withdrawal does not exceed natural recharge. Tube-well irrigation pumped water out far faster than rainfall could replace it, exactly the mechanism (applied at a smaller, regional scale) behind the Aral Sea's collapse.
Alternatives to synthetic fertilizer
Synthetic fertilizer keeps many intensive systems highly productive, but that productivity comes at the expense of long-term sustainability: fossil-fuel dependency, water pollution from runoff, and gradual soil degradation. Sustainable agriculture has other ways to maintain soil fertility. Fallowing rests land between crops so it can recover naturally. Organic fertilizer from farm animals or humanure recycles nutrients that would otherwise be lost. Herbal mixed leys (temporary grass and herb pasture rotated with crops) and mycorrhizae (fungi that form beneficial partnerships with plant roots, extending their effective root network) both build soil fertility biologically rather than chemically. Continuous cover forestry and agroforestry keep the ground permanently covered with vegetation, maintaining soil structure and nutrient cycling year-round.
Soil conservation techniques
Soil conservation techniques address different problems, and being able to tell them apart by which problem they solve is exactly what exam questions test. Water erosion is countered with terracing, contour ploughing, bunding, drainage systems, and cover crops. Wind erosion is countered with tree or hedge windbreaks and cover crops. Fertility loss is countered with soil conditioners like lime and organic materials such as compost or green manure. Poor cultivation practices are countered by avoiding marginal or overgrazed land, strip cultivation, mixed cropping, crop rotation, reduced tillage, agroforestry, and reduced use of heavy machinery.
A field on a windswept, treeless plain loses topsoil during dry, gusty months even though rainfall there is light. Which conservation technique is the best match for this specific problem?
A gently sloping field, fine for machinery access, loses a thin layer of soil to sheet erosion during heavy rain. Full terracing would be expensive and disproportionate at this scale. What is the more proportionate technique here?
A field has grown the same single crop every season for fifteen years. Rainfall is adequate and there is no visible erosion, but yields have steadily declined. Which practice addresses this specific problem?
Diets and trophic level
Humans are omnivorous: our diets naturally include fungi, plants, meat, and fish. But diets lower in trophic level tend to be more sustainable, because energy is lost at each transfer between trophic levels. The yield of food per unit of land area is greater in quantity, and lower in environmental cost, when that land grows crops directly for human consumption rather than growing crops to feed livestock that are then eaten. This does not mean diets must exclude meat and fish entirely, but it does mean a plant-heavier diet generally makes more efficient use of a finite land area.
Feeding 9.7 billion people without more land
By 2050, the global population is projected to reach about 9.7 billion, up from roughly 8.2 billion today, an 18% increase. Land is finite, so simply farming more of it is not a sustainable strategy on its own. The strategies that actually get discussed at a global level are the ones below: increase productivity on the land already farmed, and cut the amount of food that is lost or wasted before anyone eats it.
The starting numbers: today, at least 30% of food produced is lost or wasted somewhere between the field and the plate (pre-retail losses plus retail and consumer waste combined). That means only about 70 index-points of today's 100 actually reach a plate. If population grows 18% by 2050 and everyone keeps eating the same amount per person, the world needs about 18% more food actually reaching people, so the target is 70 × 1.18 ≈ 83, the dashed line below, without expanding the roughly 1.6 billion hectares of cropland already in use.
Try it: reset both sliders to zero, then move only the waste-reduction slider until the bar reaches 83. Reset again and move only the yield slider until it reaches 83. Which lever gets you there with a smaller change, and what does that suggest about which strategy is worth prioritizing first?
SDG target 12.3 aims to halve retail and consumer food waste by 2030, a 50% reduction on this slider.
This is 5.2.11: global strategies for sustainable food supply include reducing demand and food waste, and increasing productivity, without increasing the area of land used for agriculture. Notice that yield increase alone, or waste reduction alone, may not be enough. Combining both is what closes the gap without a third, land-hungry option.
Model: a simplified index that holds per-capita food demand constant and assumes yield gains and waste reduction apply uniformly. Real food systems vary hugely by region, crop, and income level. Population figures: UN DESA World Population Prospects 2024. Waste baseline: UNEP Food Waste Index Report 2024 plus FAO pre-retail loss estimates.
Food security
Food security is the physical and economic availability of food, allowing all individuals to get the balanced diet they need for an active and healthy life. Both halves of that definition matter for an exam answer: food has to physically exist and be reachable (not blocked by conflict, poor infrastructure, or distance), and it has to be affordable to the people who need it. Food security varies enormously between regions of the world, and even within a single country, and a region can be food secure in an average year while remaining highly vulnerable to a single bad harvest, price shock, or conflict.
Apply your knowledge: a new food system
Challenge 1
Transfer test. A rapidly growing coastal city has almost no farmland left within its boundaries, and importing food from distant regions raises both cost and greenhouse gas emissions from transport. Using ideas from this tab, suggest and justify one strategy the city could use to improve its food security without expanding agricultural land elsewhere.
Your explanation
- High-tech greenhouse or vertical farming within the city increases productivity per unit of land dramatically, well suited to a dense urban area with little farmland but proximity to consumers.
- Reducing food waste at the retail and consumer level (shorter supply chains, better storage, consumer education) recovers usable food without needing any new land at all.
- A shift toward a lower-trophic-level diet in the city reduces the land area required to feed the same number of people, since crop-based calories require far less land than the equivalent calories from livestock.
- Punjab groundwater decline rates and over-exploited block classification: Central Ground Water Board (CGWB) 2020 assessment, reported via Mongabay-India and Scroll.in.
- Global population 2026 and 2050 projection: UN DESA, World Population Prospects 2024 (medium variant).
- Global cropland area (~1.6 billion hectares): FAOSTAT Analytical Brief; Our World in Data land-use analysis.
- Food loss and waste figures: UNEP Food Waste Index Report 2024; FAO pre-retail loss estimates.
- SDG target 12.3 (halve food waste by 2030): UN Sustainable Development Goals framework.
- IB Environmental Systems and Societies Guide, first assessment 2026, Topic 5, Subtopic 5.2, statements 5.2.7-5.2.12.
Application of skills
The two skills for this subtopic: studying a real pair of contrasting agricultural systems in depth, and designing a survey that actually produces usable data.
Study a pair of contrasting agricultural systems
A detailed study of a contrasting pair means holding two real, named systems side by side, intensive Green Revolution farming and a slower, agroecological alternative, and reasoning carefully about what each one's numbers actually show. The three scenarios below use Punjab's real wheat-belt figures to test exactly that kind of reasoning.
Where the numbers come from: Punjab's real recorded wheat yields (about 1.3 t/ha in 1965, rising to about 5.1 t/ha by 2024/25) and the real, accelerating groundwater decline documented by India's Central Ground Water Board. Any agroecological comparison figures referenced are hypothetical and explicitly labeled as such, plausible illustrations, not measured data.
Punjab's wheat yield rose from about 1.3 t/ha in 1965 to about 5.1 t/ha by 2024/25 under an intensified Green Revolution strategy. Over roughly the same period, groundwater decline accelerated from about 18 cm/year to about 75 cm/year, and nearly 80% of the region's groundwater blocks are now classified as over-exploited. Which conclusion is best supported when comparing this path against a slower, agroecological alternative?
A student writing a Compare-level answer about intensive versus agroecological farming states only: "Agroecological farming is better because it doesn't use synthetic chemicals." What is missing from this as a Compare-level answer?
A case study cites Punjab's real 1965-2025 yield and groundwater figures alongside estimated figures for a hypothetical agroecological alternative. In an Evaluate-style answer, how should the two data types be treated?
5.2.5's application of skills asks for a detailed study of one example of a pair of named contrasting systems. Use a real contrasting pair (for example, intensive Green Revolution farming versus agroecological conservation farming), then write up the comparison using real Punjab figures on one side and clearly labeled hypothetical or illustrative figures on the other.
Design a survey on food preferences and worldviews
A good survey investigating food preferences and the worldviews behind them needs more than a list of questions. It needs a sampling method that avoids bias, question wording that does not lead the respondent toward an answer, and a sample size large enough to draw a real conclusion from.
A student survey asks: "Don't you agree that eating less meat is the responsible choice?" What is the main design flaw with this question?
To investigate food preferences across an entire school, a student surveys everyone standing in the cafeteria's vegetarian lunch line on one day. What is the main sampling problem here?
A survey asks: "Do you think school lunches should be more sustainable and cheaper?" What is the main design flaw with this question?
A worldview question benefits from open questions ("What factors influence your food choices?") alongside closed, scaled questions ("Rate how much environmental impact influences your food choices, 1 to 5"), since open questions capture reasoning a closed scale cannot, while closed questions are what actually get analyzed statistically across a large sample.
- Punjab wheat yield trajectory (1965-2025): Indian Council of Agricultural Research (ICAR) statistics.
- Groundwater decline acceleration: Central Ground Water Board (CGWB) 2020 assessment.
- IB Environmental Systems and Societies Guide, first assessment 2026, Topic 5, Subtopic 5.2, application of skills statements linked to 5.2.5 and 5.2.17.
Glossary
- Marginalized group
- A community with low political or economic power, less able to influence land-use decisions that affect it and more likely to be displaced without compensation.
- Food waste
- Edible food discarded after reaching retail or the consumer, distinct from food loss, which happens earlier in the supply chain.
- Food loss
- Edible food that never reaches retail, lost during harvest, storage, or transport.
- Arable farming
- Growing crops on cultivated land, as opposed to raising livestock.
- Pastoral farming
- Raising livestock, often on land unsuitable for arable crops.
- Monoculture
- Growing a single crop species over a large area, usually to maximize yield and simplify management.
- Commercial agriculture
- Farming carried out to sell the output, typically at scale.
- Subsistence agriculture
- Farming carried out mainly to feed the farmer's own household, with little or no surplus sold.
- Intensive farming
- High inputs of labor, capital, fertilizer, or machinery per unit of land, to maximize output from a small area.
- Extensive farming
- Low inputs per unit of land, spread across a larger area, typical of grazing systems.
- Hydroponic farming
- Growing crops in a nutrient solution rather than soil.
- Nomadic pastoralism
- Herding livestock across seasonal migration routes rather than farming a fixed plot.
- Slash-and-burn agriculture
- Clearing land by burning vegetation, farming it for a few seasons, then leaving it to regrow (fallow) before reuse.
- Fallowing
- Resting farmland, leaving it unplanted for a period so soil fertility can recover naturally.
- Green Revolution
- The mid-20th-century combination of high-yielding crop varieties, expanded irrigation, synthetic fertilizer, and pesticides that sharply raised global food production from the 1950s and 1960s onward.
- Synthetic fertilizer
- Chemically manufactured fertilizer, commonly nitrogen-based, that boosts crop yield but depends on fossil fuels to produce.
- Humanure
- Composted human waste used as an organic fertilizer.
- Mycorrhizae
- Fungi that form a beneficial partnership with plant roots, extending the plant's effective root network and improving nutrient uptake.
- Agroforestry
- Deliberately growing trees and crops or livestock together on the same land, combining their benefits.
- Terracing
- Cutting a slope into a series of flat steps to slow water runoff and reduce soil erosion.
- Contour ploughing
- Ploughing along the natural contours of a slope rather than up and down it, slowing water runoff.
- Windbreak
- A row of trees or hedges planted to reduce wind speed at ground level and limit wind erosion.
- Crop rotation
- Growing a planned sequence of different crops on the same land across seasons, maintaining soil fertility and reducing pest buildup.
- Trophic level
- A feeding position in a food chain; diets sourced from lower trophic levels (more plant-based) require less land and energy per calorie than diets higher up the chain.
- Food security
- The physical and economic availability of food, allowing all individuals to get the balanced diet they need for an active and healthy life.
- Regenerative farming
- Farming that actively rebuilds soil health and biodiversity rather than just maintaining or extracting from it.HL
- Permaculture
- A design approach for agricultural systems that mimics natural ecosystem patterns to be self-sustaining with minimal external input.HL
- Rewilding
- Restoring land to a more natural, self-regulating state, often by reducing human management and reintroducing missing species or processes.HL
- Zero tillage
- Planting crops without ploughing the soil first, preserving soil structure and reducing erosion.HL
- Mob grazing
- Moving livestock through small paddocks at high density for short periods, mimicking wild herd grazing to improve soil.HL
- Vertical farming
- Growing crops in stacked layers, often indoors under controlled conditions, to maximize yield per unit of ground area.HL
- Food miles
- The distance food travels from production to consumer, used as one (imperfect) proxy for a food's transport-related environmental impact.HL
- Planetary health diet
- A diet framework developed by the Eat-Lancet Commission, aimed at meeting nutritional needs while keeping food production within safe environmental limits.HL
- Malnutrition
- A health condition from an imbalanced diet, covering both undernourishment (too little food or too few nutrients) and overnourishment (excess food, especially low-nutritive, highly processed food).HL
- Famine
- Severe, widespread food shortage causing significant mortality, typically driven by both production failure and distribution or conflict problems together.HL
Test Yourself is coming soon for this subtopic
Practice questions and markschemes for this page are still being written. Check back once they have been added.
Contrasting choices by biome
Agricultural choices are often best understood as a contrasting pair from the same biome, one intensive, one extensive, shaped by the same soil and climate. Explore four real examples below.
Tap a biome above to see its named contrasting pair.
Alternative farming approaches
The current ecological crisis has driven a range of alternative farming approaches, each targeting a different combination of problems: food sustainability, water quality, local economic stability, and restoring or conserving soils. Soil regeneration and permaculture rebuild soil health directly. Rewilding reduces active management and lets natural processes take back over. Non-commercial cropping and zero tillage reduce a farm's environmental footprint without necessarily maximizing yield. Regenerative and permaculture systems specifically often use mixed techniques: animals such as pigs or chickens to clear vegetation and disturb soil in place of machinery, or mob grazing, moving livestock through small paddocks at high density for short periods to mimic the effect of wild grazing herds on soil.
A regenerative farm uses mob grazing, moving cattle through small paddocks at high density for only a day or two at a time. What is the main soil benefit of this technique compared with letting cattle graze one large paddock continuously?
Continuous grazing on one large paddock lets cattle selectively overgraze the same favorite patches repeatedly, weakening them. Mob grazing forces even, brief use of each patch followed by a long rest, closer to the pattern wild grazing herds created, which is what regenerative techniques are trying to recreate.
Technology, diets, and supply chains
Technology can push productivity far higher than traditional methods allow. Modern high-tech greenhouses and vertical farming, growing crops in stacked layers, often indoors, are increasingly important for supplying dense urban areas with fresh food close to where it is consumed. These improvements are not automatically sustainable, since many depend heavily on fossil fuels for heating, lighting, or climate control. Diet sustainability depends on more than what is eaten: supply chain length (the social, economic, and physical distance food travels), year-round demand driving food miles, and cultural shifts such as rising veganism or lower meat consumption all affect a diet's overall footprint. The planetary health diet, developed by the Eat-Lancet Commission, is one influential framework aiming to meet nutritional needs while keeping food production within safe environmental limits.
A vertical farm produces very high yields per square meter of floor space, but runs entirely on electricity from a coal-fired grid. Is this system automatically sustainable because it is highly productive?
Wild harvesting and low-productivity systems
Harvesting wild species by traditional methods, Brazil nuts, truffles, bamboo shoots, honey, edible insects, can be more sustainable than clearing land to cultivate a substitute crop, since the ecosystem stays intact rather than being converted. The same claim becomes far more contested for harvesting controversial or endangered species, such as pangolins, bears, or other bushmeat, where "traditional" does not automatically mean sustainable at current levels of demand and population.
A related and harder claim is that low-productivity indigenous, traditional, or alternative food systems could resolve global food unsustainability on their own. That claim has to be weighed against the reality that world agriculture must still produce enough food for eight billion people. A system with ecological benefits at a small scale does not automatically scale up to meet global demand without losing the very features that made it sustainable in the first place.
"More sustainable than the alternative" is not the same claim as "sustainable enough to feed everyone." A traditional low-input system can be much less damaging per hectare than an intensive one, while still being unable to produce enough food, on its own, to meet global demand at low-productivity yields. A strong Evaluate-level answer holds both of those facts at once rather than picking one and ignoring the other.
Distribution, food quality, and malnutrition
Food distribution patterns and food quality variation reflect how the global food supply industry actually functions, and both can lead to malnutrition, a category covering both undernourishment (too little food or too few nutrients) and overnourishment (excess food, often low-nutritive or highly processed). Famine is caused as much by distribution failure as by crop failure. The Irish potato famine (1845 to 1849) followed potato blight destroying the crop that much of the population depended on almost exclusively. East African famines have repeatedly been caused by a combination of drought and armed conflict disrupting both production and distribution at once.
It is a common misconception that more biomass or more calories automatically means better nutrition. Food can be abundant in mass while being low in nutritive value or highly processed, so a population can be simultaneously overfed by calories and undernourished by nutrients, a pattern increasingly common alongside traditional undernourishment.
- Biome-soil-agriculture pairings (mollisol, oxisol, aridisol, temperate brown earth): standard soil taxonomy and agricultural geography references, cross-checked against subtopic 5.1.
- Planetary health diet: Eat-Lancet Commission framework.
- Irish potato famine (1845-1849) and East Africa famines: widely documented historical and contemporary famine records, as referenced directly in the IB Guide.
- IB Environmental Systems and Societies Guide, first assessment 2026, Topic 5, Subtopic 5.2, statements 5.2.13-5.2.20.