Agroforestry – SS2 Horticulture and Crop Production Lesson Note (First Term)

Class: SS2

Subject: Horticulture and Crop Production

Agroforestry is a farming system in which woody perennials, such as trees or shrubs, are deliberately grown on the same land as agricultural crops or livestock.

Behavioural objectives

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

1. define agroforestry;
2. name the three components of agroforestry and the types formed when they are combined;
3. describe alley cropping, the taungya system, shelterbelts and home gardens;
4. state the benefits of agroforestry;
5. state the challenges of agroforestry.

What is agroforestry?

Agroforestry is a land-use system that combines forestry and agriculture on one piece of land.

• Woody perennials: trees or shrubs that live for many years, such as mango, teak and Gliricidia.
• Deliberate planting: the farmer chooses and plants the trees, and does not just leave a few trees standing by chance.
• Same land: trees, crops or animals share the plot at the same time or one after another.
• Natural pattern: in a forest, tall trees, bushes and ground plants grow together, and agroforestry copies this idea.
• Single-crop farm: a plot of only maize or cassava has no trees, so it does not count as agroforestry.

What are the three components of agroforestry?

The three components of agroforestry are trees, crops and animals.

1. The trees (silviculture): fruit trees, timber trees or nitrogen-fixing shrubs.
2. The crops (agriculture): maize, yam, cassava or vegetables.
3. The animals (pasture/livestock): cattle, goats or sheep.

What are the types of agroforestry?

There are three types of agroforestry: agrisilviculture, silvopastoral and agrosilvopastoral.

• Agrisilviculture: trees + crops, such as maize grown between rows of trees.
• Silvopastoral: trees + livestock, such as goats grazing under shade trees.
• Agrosilvopastoral: trees + crops + livestock, which is the full combination.

What are the common agroforestry practices?

The common agroforestry practices in Nigeria are alley cropping, the taungya system, shelterbelts and home gardens.

What is alley cropping?

Alley cropping is the planting of food crops in the wide spaces (alleys) between rows of fast-growing trees or shrubs.

• Layout: the farm looks like it has “streets”, with tree rows and crop alleys side by side.
• Trees used: fast-growing, nitrogen-fixing trees such as Gliricidia.
• Crops used: maize and similar food crops.
• Benefit: the trees drop leaves that act as fertiliser for the crops.

Steps in alley cropping:

1. Clear the land and mark out straight rows.
2. Plant the tree or shrub rows with wide spaces between them.
3. Plant the food crop in the alleys.
4. Prune the tree rows regularly so they do not shade the crops.
5. Spread the cut leaves and twigs on the soil as mulch and fertiliser.

What is the taungya system?

The taungya system is a practice in which farmers grow food crops between young timber trees while a new forest is being started.

• The deal: the farmer gets land to grow food and, in return, takes care of the young trees.
• Benefit to the farmer: free land for food crops in the early years.
• Benefit to the forest owner: the trees are planted and weeded at little cost.
• End of the cycle: once the trees grow big and shade out the crops, the farmer moves to a new patch.

Steps in the taungya system:

1. The farmer is given a piece of land to start a forest plantation.
2. The farmer clears the land and plants the young timber trees.
3. The farmer plants food crops between the young trees.
4. The farmer weeds and looks after both crops and trees.
5. The farmer harvests the crops until the trees shade them out.
6. The farmer moves to a new patch and the trees are left to grow.

What are shelterbelts (windbreaks)?

A shelterbelt is a long line of tall, strong trees planted at the edge of a farm to reduce the force of the wind.

• Wall effect: the trees act like a “wall” that stops heavy wind from blowing down crops such as maize.
• Moisture: they reduce the wind that dries out the soil.
• Soil: they help to reduce wind erosion of loose topsoil.

What is a home garden?

A home garden is a mixed plot of trees, vegetables and sometimes small livestock around a house.

• Trees: fruit trees such as mango and citrus.
• Crops: vegetables grown beneath or beside the trees.
• Animals: sometimes a few chickens in the backyard.
• Where seen: in many compounds in towns and villages.

How do the four practices compare?

Why is agroforestry important?

Agroforestry is important because trees protect the soil, feed the crops and give the farmer extra products to sell.

• Soil fertility: trees like Gliricidia take nitrogen from the air and add it to the soil, so they act like a free fertiliser factory.
• Extra income: a farmer can sell oranges from the trees, timber for construction or firewood, as well as maize.
• Climate control: trees give shade, which keeps the soil cool and helps it hold water longer in the dry season.
• Soil protection: tree roots hold the soil together, so heavy rain does not wash the topsoil away (erosion control).
• Sustainability: the farmer keeps the farm productive for the future, instead of clearing every tree.

What are the challenges of agroforestry?

The main challenges of agroforestry are competition, pests and slow returns, so the system needs good management.

1. Competition: the wrong trees may take most of the sunlight and water from the crops.
2. Pests: trees can give a home to birds or insects that eat the crops.
3. Patience: crops grow in about 3 months, but trees take years, so the farmer must wait for the long-term rewards.
4. Management: trees need pruning and spacing, which adds work for the farmer.

Classroom discussion

• Look around your school or home and identify any agroforestry.
• Find out if any tree gives shade to a vegetable patch.
• Discuss which trees you would choose to plant on your own farm, and why.

Evaluation

1. Define agroforestry.
2. Name the type of agroforestry that combines trees, crops and livestock.
3. Describe the taungya system.
4. State three benefits of agroforestry.
5. State two challenges a farmer may face when practising agroforestry.

Assignment

Explain how alley cropping and shelterbelts each benefit a farmer. Give one example of a tree and one example of a crop that can be grown in an agroforestry system, using examples from this note.