Sustainable Horticultural Practices – SS3 Horticulture and Crop Production Lesson Note (First Term)

Sustainable horticulture is the growing of fruits, vegetables and flowers in ways that protect the soil, water and living things, so that farming can continue for future generations.

Behavioural objectives

By the end of the lesson, students should be able to:

1. explain what sustainable horticulture means;
2. describe organic farming and name its methods of feeding the soil and controlling pests;
3. state the meaning and the three ethics of permaculture;
4. describe zoning, the food forest layers, and mulching and no-dig;
5. give reasons for switching to sustainable practices.

What is sustainable horticulture?

Sustainable horticulture is a way of growing crops that leaves the soil healthier than it was found.

• Chemical farming: uses synthetic fertilisers to make plants grow fast and heavy pesticides to kill every bug in sight.
• Short-term gain: this works for a time, but it tires out the soil.
• Harm to living things: it kills friendly insects such as bees and can leave residues on food.
• Custodian: a sustainable farmer looks after the land for the future instead of using it up.

What are the main sustainable approaches?

There are two main approaches taught in this lesson: organic farming and permaculture.

• Organic farming: grows crops without man-made chemicals.
• Permaculture: designs the whole land to work like a forest.

What is organic farming?

Organic farming is the growing of crops without man-made chemicals such as synthetic fertilisers and pesticides.

• It is like the way our grandparents farmed, but with modern scientific knowledge.
• Its main idea is to keep the soil alive and fertile.

How does organic farming feed the soil?

In organic farming the farmer feeds the soil, and the soil then feeds the plant.

What are the organic ways of feeding the soil?

• Compost: “black gold” made when kitchen scraps, dry leaves and animal manure rot into rich, dark soil.
• Animal manure: droppings from poultry, goats or cattle that add nutrients and organic matter.
• Green manure: crops such as beans or clover grown to be turned back into the soil, adding natural nitrogen.
• Mulch: a cover of straw or leaves that rots slowly and feeds the soil.
• Crop rotation: changing the crop grown on a plot each season so that the soil is not drained of the same nutrients.

How is compost made?

1. Collect green materials (kitchen scraps, fresh leaves, manure) and dry materials (dry leaves, straw).
2. Pile them in layers in a heap or pit.
3. Keep the heap moist but not soaked.
4. Turn the heap now and then to let in air.
5. Use it when it is dark, crumbly and smells of earth.

How does an organic farmer control pests?

An organic farmer controls pests with natural methods instead of spraying poison.

• Neem oil: a natural spray from the neem tree that repels many insects.
• Companion planting: growing onions or garlic next to tomatoes, because the strong smell confuses pests that want to eat the tomatoes.
• Friendly insects: encouraging ladybirds (ladybugs) to live on the farm, because they eat aphids that suck the juice out of plants.
• Hand-picking: removing large pests such as caterpillars by hand.
• Crop rotation: breaks the life cycle of pests that attack one type of crop.

What is permaculture?

Permaculture is a way of designing the whole land so that it works like a natural forest; the word comes from “permanent agriculture”.

What are the three ethics of permaculture?

1. Earth care: looking after the soil, water and forests.
2. People care: growing healthy food for the family and community.
3. Fair share: taking only what you need and returning the extra (like seeds or compost) to the system.

What are the key permaculture techniques?

The key techniques are zoning, the food forest layers, and mulching with no-dig.

What is zoning?

Zoning is placing plants and activities on the land according to how often they need attention.

• Main rule: things needed every day go close to the house, and things needing less care go further away.
• Benefit: it saves the farmer’s time and energy.

What are the layers of a food forest?

A food forest copies a natural forest by growing plants of different heights together in the same space.

• Canopy: tall trees, for example mango.
• Low tree layer: shorter trees growing under the canopy, for example citrus.
• Shrub layer: bushes, for example pigeon pea.
• Herb layer: soft-stemmed plants, for example scent leaf and mint.
• Ground cover: plants that spread over the soil, for example pumpkin and sweet potato.
• Vertical layer: climbers that grow up trees or poles, for example yam and passion fruit.
• Root layer: crops that grow underground, for example ginger and cassava.

What are mulching and no-dig?

Mulching is covering the soil with straw, dry leaves or similar material, and no-dig means not ploughing or digging the ground.

• Mulching: the soil is never left bare, so it keeps moisture and is protected from sun and rain.
• No-dig: digging destroys the tunnels made by earthworms, our best “mini-tractors”.
• Earthworms: they loosen the soil and mix in organic matter, so the farmer does less work.

What is the difference between organic farming and permaculture?

Organic farming is mainly about avoiding man-made chemicals, while permaculture is about designing the whole land like a natural ecosystem.

Why should we switch to sustainable practices?

We should switch because sustainable practices protect the soil, save money and give safer food.

• Healthier food: organic fruits and vegetables carry fewer chemical residues.
• Low cost: you do not need to buy expensive imported fertilisers, because you make plant food from what you already have.
• Resilience: soil full of organic matter acts like a sponge and holds water longer, so the farm survives dry spells better.
• Biodiversity: the farm becomes a home for birds, butterflies and helpful microbes that keep the environment balanced.

Evaluation

1. What is sustainable horticulture?
2. Explain the difference between feeding the plant and feeding the soil.
3. Name the natural pest control methods used in organic farming and explain how one of them works.
4. State the three ethics of permaculture.
5. What is zoning, and why does it save the farmer’s energy?

Assignment

1. Explain in your own words why a farm with soil rich in organic matter survives drought better. Give two other reasons for switching to sustainable practices.