IB DP Environmental Systems and Societies – Soil, agriculture and food Practice Questions

These are original questions written for Marlbridge, for revision and practice on this content. They are not reproduced past-paper questions, and they do not replicate the exam’s exact structure, question count or mark tariffs – the IB holds copyright in its own papers. Use these alongside the official past papers available through your school or the IB store.

This practice set is for IB Diploma Programme Environmental Systems and Societies, aligned to the IB Diploma Programme Subject Brief, Environmental systems and societies. It covers syllabus sections 5.1 (Soil) and 5.2 (Agriculture and food) of Topic 5, Land, which is studied at SL and HL; question 9 uses an HL-only lens and is labelled HL. It follows the IB ESS subject brief for first assessment 2026 — the course examined in the May and November 2026, 2027 and 2028 sessions.

The brief gives Topic 5 Land 8 teaching hours at SL and 15 at HL. It does not list the subtopics or learning outcomes for this topic, so the numbered subtopics and outcomes on this page follow the syllabus numbering used in the printable ESS checklist, not the brief itself.

Learn the content first in the study guide and the revision notes. The ESS course hub and printable checklist show the rest of the course, and the Topic 2 Ecology practice set covers the energy flow these questions build on. All data below are invented for these questions.

Questions

1. Identify two inputs to and two outputs from a soil system. [4]

2. The table shows the particle composition of soil from three fictional fields.

Field	Sand (%)	Silt (%)	Clay (%)	Texture class
P	88	7	5	Sand
Q	42	38	?	Loam
R	18	30	52	Clay

(a) Calculate the percentage of clay in field Q. [1] (b) Identify which field is likely to have the highest water-holding capacity, and give a reason. [2] (c) Explain why field Q is the most suitable of the three for growing arable crops. [3]

3. Outline how irrigation can lead to salinization of soil. [3]

4. A fictional trial measured soil loss from plots on the same slope under three management methods.

Method	Soil loss (t per ha per year)
Conventional ploughing downslope	24.0
Contour ploughing	13.2
No-till with a cover crop	3.6

(a) Calculate the percentage reduction in soil loss when no-till with a cover crop replaces conventional ploughing. [2] (b) Explain how contour ploughing reduces soil loss. [2] (c) Suggest two reasons why a farmer might not adopt no-till with a cover crop. [2]

5. Distinguish between (i) subsistence and commercial farming, and (ii) intensive and extensive farming. [4]

6. The table shows annual energy data for three fictional farms.

Farm	System	Energy input (GJ)	Food energy output (GJ)
A	Hand-worked subsistence rice	5.6	39.2
B	Mechanised commercial wheat	240	768
C	Beef feedlot	1800	180

(a) Calculate the energy ratio (output ÷ input) for farms A and C. [2] (b) Explain why farm C has the lowest energy ratio. [3]

7. One hectare of soya produces 29 200 MJ of food energy per year. One person needs 10 MJ per day.

(a) Calculate how many people could be fed for a year by eating the soya directly. [2] (b) The soya is instead fed to chickens. Assuming 10% of the energy passes to the chickens’ edible products, calculate the area of land needed to feed one person for a year. [2]

8. In fictional Country M, a higher-income country, 1000 kilotonnes (kt) of food is produced in a year. Losses are: production 60 kt, storage and transport 40 kt, processing 50 kt, retail 70 kt, households 180 kt.

(a) Calculate the percentage of all food lost or wasted that is wasted in households. [2] (b) Explain why the pattern of losses in a lower-income country is likely to differ from Country M. [3]

9. (HL) Using the idea of an external cost, explain why farmers may apply more nitrogen fertiliser than is best for society, and outline one policy that could reduce this. [4]

10. Evaluate intensive commercial agriculture as a way of achieving global food security. [8]

11. To what extent can soil conservation methods make food production sustainable? [9]

Answers

1. Inputs, any two: leaf litter or dead organic matter [1]; weathered parent material or precipitation or solar energy [1]. Outputs, any two: nutrient uptake by plants or leaching out of the soil [1]; erosion or evaporation [1]. [4] Examiner insight: Each named item must be a genuine input or output of the soil; storages such as “humus” or processes such as “decomposition” earn nothing here.

2. (a) 100 − 42 − 38 = 20% [1] (b) Field R [1]; it has the most clay, whose tiny pores hold water tightly [1] (c) Loam has a mixture of particle sizes, so it drains and is aerated well [1]; it still holds enough water for crops between rainfall [1]; and it retains nutrients better than the sandy field P, so less is leached [1] [6] Examiner insight: Part (c) is comparative — each point should say why Q beats P or R, not simply list what loam is like.

3. Irrigation water contains dissolved salts [1]; in hot, dry conditions the water evaporates from the surface [1]; the salts are left behind and build up in the topsoil, especially where drainage is poor, reducing crop growth [1] [3] Examiner insight: The evaporation step is the one most often missed; without it the answer does not explain how salts concentrate.

4. (a) (24.0 − 3.6) ÷ 24.0 × 100 [1] = 85.0% [1] (b) Furrows and ridges run across the slope along the contours [1]; each ridge slows runoff and traps sediment, so less soil is carried downhill [1] (c) Any two: weeds must be controlled another way, often with herbicides [1]; new equipment such as direct drills costs money [1]; yields may fall in the first years; cover crop seed and management add cost and labour [6] Examiner insight: In (a), dividing by 3.6 instead of the original 24.0 loses the accuracy mark; the method mark needs the working shown.

5. (i) Subsistence farming produces food mainly for the farmer’s household [1]; commercial farming produces crops or livestock to sell for profit [1]. (ii) Intensive farming uses high inputs of labour or capital per unit area to get high yields [1]; extensive farming uses low inputs per unit area, usually over a large area [1] [4] Examiner insight: “Distinguish” needs both sides of each pair; defining only intensive and saying extensive is “the opposite” earns one mark, not two.

6. (a) Farm A: 39.2 ÷ 5.6 = 7.0 [1]; Farm C: 180 ÷ 1800 = 0.10 [1] (b) Cattle are primary consumers, so the feed crops add an extra trophic level [1]; most energy in the feed is lost as heat in respiration and in waste, roughly 90% [1]; and the feedlot also uses large fossil fuel inputs to grow, transport and process feed [1] [5] Examiner insight: An answer about farm C must use trophic-level energy loss; “cows are inefficient” with no mechanism earns nothing.

7. (a) 10 × 365 = 3650 MJ per person per year [1]; 29 200 ÷ 3650 = 8 people [1] (b) 29 200 × 0.10 = 2920 MJ from 1 ha [1]; 3650 ÷ 2920 = 1.25 ha per person [1] [4] Examiner insight: Show each step; a bare 1.25 with no working cannot earn the method mark if it is wrong, and the answer needs its unit (ha).

8. (a) Total lost = 60 + 40 + 50 + 70 + 180 = 400 kt [1]; 180 ÷ 400 × 100 = 45% [1] (b) In a lower-income country, more food is lost early, at harvest and in storage and transport [1], because of pests, poor storage and lack of refrigeration or roads [1]; less is wasted in households because food is a larger share of income, so households rarely buy more than they will eat [1] [5] Examiner insight: In (a) the question asks for a share of losses (divide by 400), not a share of production (divide by 1000); read which total is meant.

9. Runoff of excess nitrogen causes eutrophication, which harms fisheries and water supplies downstream [1]; the farmer does not pay for this damage, so it is an external cost [1]; the private cost of fertiliser is below its full cost to society, so more is used than is socially best [1]; a tax on nitrogen fertiliser, or payments for buffer strips and precise application, makes the user bear more of the cost [1] [4] Examiner insight: The mark for “external cost” needs the idea of damage to a third party not paid for by the polluter; a policy mark needs a policy linked to that cost.

10. Indicative content — the real exam marks longer answers holistically against IB criteria your teacher will share, so treat these points as a guide. For: high-yielding varieties, fertiliser and irrigation raise output per hectare [1]; higher yields mean less land needs clearing for the same output [1]; cheaper food improves access for poorer consumers [1]. Against: fertiliser runoff causes eutrophication and pesticides harm non-target species [1]; soil degradation (compaction, erosion, salinization) threatens future yields [1]; reliance on fossil fuel inputs gives a low energy ratio and greenhouse gas emissions [1]; food security also depends on access, poverty and waste, which higher output alone does not fix [1]. Judgement: intensive farming raises availability in the short term, but only supports long-term food security if combined with soil conservation, waste reduction and fair access [1] [8] Examiner insight: “Evaluate” needs strengths, limitations and a justified conclusion; a list of impacts with no final judgement caps the answer well below full marks.

11. Indicative content, marked as a guide as in question 10. Soil is effectively non-renewable, so protecting it is a precondition of sustainability [1]; contour ploughing and terracing slow runoff and cut water erosion [1]; windbreaks and cover crops reduce wind erosion and keep the surface covered [1]; crop rotation, manure and compost maintain organic matter and nutrients, so yields can be kept up with fewer synthetic inputs [1]; drip irrigation and drainage prevent salinization [1]. Limits: conservation does not address greenhouse gas emissions from livestock or fertiliser [1]; it does not reduce food waste or change diets, which affect how much land is needed [1]; costs and labour may prevent poorer farmers adopting methods, a perspectives and equity issue [1]. Judgement: soil conservation is necessary but not sufficient — sustainability also needs changes in consumption, waste and wider farm practice [1] [9] Examiner insight: “To what extent” rewards a clear position backed by evidence on both sides; naming methods without explaining how each protects soil earns little.

Where marks are usually lost

• Naming storages or processes when a question asks for inputs or outputs.
• Swapping the properties of sand and clay, or describing loam without comparing it.
• Leaving out evaporation when explaining salinization.
• Dividing by the new value in percentage-reduction calculations.
• Giving a numerical answer without units (ha, GJ, t per ha per year) or without working.
• Using “intensive” to mean “big” or “commercial”.
• Explaining the low energy ratio of livestock without the trophic-level loss of energy as heat.
• Confusing a share of losses with a share of production in food waste data.
• Writing evaluation answers that only describe, or that end without a justified judgement.

Next steps

• Soil, agriculture and food revision notes
• Soil, agriculture and food study guide
• IB DP ESS course hub
• Printable syllabus checklist
• ESS exam preparation guide
• All free 10-minute diagnostics
• Book a free trial class

Official syllabus

International Baccalaureate Organization, Diploma Programme Subject Brief, Environmental systems and societies, first assessment 2026. This set covers syllabus sections 5.1 (Soil) and 5.2 (Agriculture and food) of Topic 5, Land. The brief lists subtopics for Topic 1 only; the subtopic numbering on this page follows the printable ESS checklist.