Explain why growing the same crop on the same land year after year can lead to reduced yields over time.

Eduqas GCSE Biology — 6.4 Biological challenges of increasing food yields · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Farmers sometimes grow the same crop repeatedly on the same fields to meet increasing food demands. However, this practice can cause problems that reduce the amount of food produced.

Model answer (4 marks)

1. The crop removes nutrients and minerals from the soil each year.
2. These nutrients are not replenished, so the soil becomes less fertile.
3. Pest and pathogen populations build up in the soil or on the land over time.
4. The increased pest and disease pressure causes greater crop damage, reducing yield.

Examiner tips

Use the exact wording from the mark scheme – e.g. "nutrients / minerals are removed" and "pest / pathogen populations build up".
Show the causal chain: removal of nutrients → soil fertility loss → pest build‑up → yield decline.
Keep each point short and separate – one sentence per point is enough for full marks.

Common mistakes

Mixing up the order of the points or combining two ideas into one sentence.
Using vague terms like "soil problems" instead of the specific causes listed in the scheme.

Mark scheme (4 marks)

Nutrients / minerals are removed from the soil by the crop each year
Nutrients are not replaced / soil becomes less fertile
Pest / pathogen populations build up in the soil or on the land over time
This leads to greater crop damage / plant disease / lower yield

Key terms in this question

yield

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