3.8 Sustainable Agriculture

2026 Syllabus Objectives

By the end of these notes, you should be able to:

  1. Describe and explain strategies for sustainable agriculture
  2. Know and understand the following specific strategies: organic fertiliser (crop residue, manure); managed grazing (livestock rotation); crop rotation; use of pest-resistant and drought-resistant varieties of crops; trickle drip irrigation; rainwater harvesting

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What is Sustainable Agriculture?

Sustainable agriculture means farming in a way that meets the food needs of people today without damaging the environment or using up resources so quickly that future generations cannot also meet their needs.

Think of it like this: if you keep withdrawing money from a bank account without ever putting any back, eventually the account runs dry. Unsustainable farming does the same to the land — it takes and takes until the soil, water, and wildlife are depleted. Sustainable agriculture tries to "put back" what it takes.

The goal is to:

  • Produce enough food to feed people
  • Protect the environment (soil, water, air, biodiversity)
  • Ensure farming can continue long into the future

Strategy 1: Organic Fertilisers

What is a fertiliser?

A fertiliser is any substance added to the soil to provide nutrients that help plants grow. The three most important nutrients for plants are nitrogen (N), phosphorus (P), and potassium (K).

What makes a fertiliser "organic"?

An organic fertiliser comes from natural, living sources — not from a factory. It is made from things that were once alive.

There are two main types you need to know:

1a. Crop Residue

  • Crop residue refers to the parts of a plant left over after harvest — for example, stalks, leaves, roots, and husks.
  • Instead of burning or throwing these away, farmers leave them on the field or mix them into the soil.
  • Over time, tiny organisms called decomposers (like bacteria and fungi) break down this plant material. This process is called decomposition.
  • As the material breaks down, it releases nutrients back into the soil — nutrients that the next crop can use to grow.
  • It also improves the soil structure (the way soil particles are arranged), making the soil better at holding water and air.

Why it's sustainable:

  • It recycles nutrients rather than wasting them.
  • It reduces the need for artificial (chemical) fertilisers, which are expensive and can pollute waterways.

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