3.4 Increasing Agricultural Yields

2026 Syllabus Objectives

By the end of this topic, you should be able to:

  1. Describe the techniques used to increase agricultural yields
  2. Know and explain the following specific techniques: rotation, fertilisers, irrigation, insect control (insecticides and biological control), weed control (herbicides), fungi control (fungicides), mechanisation, selective breeding of animals and plants, genetically modified organisms (GMOs), and controlled environments (greenhouses and hydroponics)

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What Does "Agricultural Yield" Mean?

Agricultural yield simply means the amount of food or crop produced from a given area of land. Farmers always want to increase yield — in other words, grow more food from the same amount of land. This is important because the world's population keeps growing, so more food is needed every year.

There are many different techniques farmers use to increase yield. Let's go through each one carefully.

1. Crop Rotation

Crop rotation means growing different types of crops on the same piece of land, one after another, in a planned sequence — instead of growing the same crop every single year.

Why is this useful?

  • Different crops use different nutrients from the soil. If you grow the same crop year after year, the soil runs out of those specific nutrients very quickly.
  • Some crops, called legumes (e.g. peas, beans, clover), have a special ability: tiny bacteria living in their roots can take nitrogen gas from the air and convert it into nitrates — a form of nitrogen that plants can absorb. This is called nitrogen fixation. By including a legume in the rotation, farmers naturally put nitrogen back into the soil.
  • Rotation also helps reduce the build-up of pests and diseases in the soil, because the pest that attacks one crop won't thrive when a completely different crop is planted the next year.

Example of a simple 4-year rotation:

  1. Year 1 — Wheat (uses nitrates)
  2. Year 2 — Root vegetables like turnips (uses different nutrients)
  3. Year 3 — Legumes like clover or beans (restores nitrogen to the soil)
  4. Year 4 — Barley

This cycle then repeats. The result is healthier soil and better yields over time.

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