Maintenance of Crops – SS1 Horticulture and Crop Production Lesson Note (Third Term)

Crop maintenance, also called post-planting operations, is everything a farmer does to keep plants healthy, strong and productive after planting.

Behavioural objectives

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

1. define crop maintenance, thinning, mulching, pruning and staking;
2. state the reasons for thinning, mulching, pruning and staking;
3. describe how to thin seedlings and how to stake a plant;
4. name the materials used for mulching and the tools used for pruning;
5. give examples of crops that suit each operation.

Why do we maintain crops?

We maintain crops because a planted seed still needs care to grow into a healthy, high-yielding plant.

• Weeds: they choke young plants if nobody removes them.
• Sun and heat: they dry the soil and stress the plant.
• Weak stems: a heavy plant may bend or snap without support.
• Crowding: too many seedlings compete for water and nutrients.

What are the main crop maintenance operations?

There are four main maintenance operations covered here: thinning, mulching, pruning and staking.

1. Thinning: gives seedlings enough space.
2. Mulching: protects the soil.
3. Pruning: removes unwanted plant parts.
4. Staking: gives weak stems support.

What other operations belong to crop maintenance?

• Weeding: removing unwanted plants that compete with the crop.
• Watering: supplying water when rainfall is not enough.
• Manuring and fertiliser application: adding nutrients to the soil.
• Supplying: replacing seeds or seedlings that failed to grow.
• Pest and disease control: protecting the crop from damage.

What is thinning?

Thinning is the removal of excess, weak or overcrowded seedlings so that the remaining ones grow better.

• Why it is needed: farmers often put 2 or 3 seeds in one hole of crops like maize or okra to be sure at least one grows.
• The problem: if all the seeds grow, the seedlings crowd one another.

Why do we thin?

• No competition: plants do not fight over the same small amount of water, light and fertiliser.
• Better health: one strong plant does better than three tiny, hungry plants.
• Better yield: the remaining plants have room to grow bigger and produce more.

How do we thin seedlings?

1. Choose the strongest, healthiest seedling in each stand to keep.
2. Press the soil down firmly around the seedling you are keeping.
3. Gently pull out the weaker seedling, or cut it off at soil level.
4. Take care not to disturb the roots of the plant you are keeping.
5. Water the stand lightly if the soil is dry.

What is mulching?

Mulching is covering the soil surface around crops with a layer of material to protect it.

• Simple picture: mulch is the soil’s blanket.
• Why it matters: bare soil becomes very hot in the afternoon, and plant roots feel that heat.

What materials are used for mulching?

• Dry grass: cheap and easy to find on most farms.
• Dry leaves: collected from trees and cleared plots.
• Wood shavings and sawdust: available from sawmills.
• Straw and crop residues: such as dry maize stalks.
• Polythene sheets: a non-living mulch that does not rot.

Why do we mulch?

1. To save water: it reduces evaporation of moisture from the soil.
2. To control weeds: it blocks sunlight, so weeds cannot grow easily.
3. To keep the soil cool: it protects delicate roots from the direct heat of the sun.
4. To add manure: as dry grass and leaves rot, they add humus and nutrients to the soil.
5. To reduce erosion: it lessens the impact of raindrops on bare soil.

What precaution do we take when mulching?

• Keep mulch away from the stem: mulch touching the stem keeps it damp and can cause it to rot.
• Leave a small gap: spread the mulch around the plant, not against it.

What is pruning?

Pruning is the careful removal of specific parts of a plant, such as branches, buds or roots.

• Simple picture: pruning is like giving the plant a haircut.
• When it is done: when a plant has too many branches, or when leaves and branches are dry or diseased.

Why do we prune?

• Focus on fruit: the plant spends less energy on extra leaves and more on bigger fruits.
• Better airflow: breeze moves through the plant, which helps prevent diseases.
• Better sunlight: light reaches the inner branches and leaves.
• Safety: removing dead or diseased branches stops the sickness spreading to the whole plant.
• Shape and size: it keeps the tree low enough to spray and harvest easily.

Which tools do we use for pruning?

• Secateurs: hand shears that cut small branches cleanly.
• Sharp knife: used for soft stems, buds and small shoots.
• Pruning saw: used for thick branches that secateurs cannot cut.

What rules guide good pruning?

• Use sharp tools: they make clean cuts and do not tear the plant’s bark.
• Clean the tools: wipe them after cutting a diseased branch so the disease does not spread.
• Cut just above a bud or node: this helps the cut heal and new growth to form.

What is staking?

Staking is providing a physical support, usually a wooden stick or bamboo, for a plant to lean or climb on.

• Plants that need it: tomatoes, peppers and yams have weak stems or carry heavy fruits.
• If left alone: they fall on the damp ground and rot.

Why do we stake?

• To keep fruits clean: tomatoes stay off the dirt, so they rot less and ground insects reach them less.
• Better sunlight: the leaves reach up towards the sun.
• Easier harvest: a farmer can see and pick peppers easily when plants stand tall.
• Less breakage: the support stops heavy stems from snapping.

How do we stake a plant?

1. Collect strong sticks or bamboo and a soft string, such as raffia.
2. Drive a stake firmly into the ground near the plant, while the plant is still small.
3. Take care not to injure the roots when driving in the stake.
4. Tie the stem loosely to the stake with the soft string.
5. Add more ties as the plant grows taller.

• Warning: a tight tie chokes the stem and stops it from growing thicker.

Which crops suit each operation?

Each operation suits certain crops best, as shown in the table.

Evaluation

1. What is crop maintenance?
2. Define thinning and state two reasons for doing it.
3. Name three mulching materials and state one benefit of mulching.
4. Name two tools used for pruning and give two reasons for pruning.
5. Describe how to stake a tomato plant.

Assignment

1. Choose one crop from the table above. State the operation that suits it best, describe how the operation is carried out, and explain why mulch should not touch the stem of a plant.