Storage Structures – SS2 Horticulture and Crop Production Lesson Note (Second Term)

Storage is the keeping of agricultural produce in good condition from harvest until it is needed for eating or selling.

Behavioural objectives

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

1. define storage and post-harvest loss, and state why farmers need storage;
2. describe the barn, the silo, the refrigerator and the cold room;
3. state one benefit and one problem of the barn and of the silo;
4. state the difference between a refrigerator and a cold room;
5. state the three simple rules for good storage.

What is storage and why do farmers need it?

Storage is the art of keeping produce in good condition from harvest until it is eaten or sold.

• Example: a farmer harvests 100 baskets of tomatoes but can sell only 10 that day. Without storage, the other 90 rot in the sun.
• Reduces loss: good storage prevents post-harvest loss, one of the biggest problems for farmers in Nigeria.
• Better prices: a farmer can harvest in October and sell in March, when prices are higher.
• Steady food supply: food is available in the off-season, when little is being harvested.
• Goal of every structure: keep it cool, keep it dry and keep the pests out.

What is post-harvest loss?

Post-harvest loss is the damage or waste of produce between harvest and consumption.

• Pests: weevils eat grains, and rats and squirrels eat yams and cobs.
• Moulds and rot: wet or warm produce is attacked by fungi and bacteria.
• Heat: hot sun makes tubers shrink and lose weight, and makes vegetables wilt.
• Poor handling: bruised or cut produce spoils faster than sound produce.

What are the types of storage structures?

Four common storage structures are the barn, the silo, the refrigerator and the cold room, and each suits different crops and farm sizes.

What is a barn?

A barn is an open-air structure of wooden poles and palm fronds, used to store yams, coco-yams and sometimes maize.

• How it works: yams are tied vertically to the poles with rope or local twine, and the fronds give some shade.
• Benefit: plenty of air (ventilation) moves around the tubers, which keeps them cool and slows rotting.
• Problem: rats and squirrels can climb the poles and eat the yams.
• Problem: harsh sun can make the yams shrink and lose weight.

What is a silo?

A silo is a tall, airtight cylinder of metal or concrete used to store large amounts of grain such as maize, rice and cowpea.

• How it works: grain is dried thoroughly and then poured in from the top.
• Benefit: because the silo is airtight, the oxygen is used up and pests such as weevils die.
• Benefit: grain can be kept fresh for a long time.
• Problem: silos are very expensive to build.
• Problem: if the grain is even slightly wet, mould grows and the whole silo can spoil.

What are the crib and the granary?

The crib and the granary are traditional structures for storing cereals on the farm.

• Crib: a raised structure with slatted or mesh sides and a roof, used to dry and store maize cobs.
• Granary: a raised store, often of mud or woven material with a thatched roof, used for threshed grain.

What are refrigerators and cold rooms?

Refrigerators and cold rooms are electric cooling stores for delicate horticultural crops.

• Why cooling is needed: crops such as lettuce, cabbage, strawberries and cut flowers are mostly water.
• Why they spoil fast: they keep breathing after harvest, so they wilt and decay quickly.

Refrigerator

A refrigerator is a small electric cooling box for storing small amounts of produce, usually in homes or small shops.

• How it works: it uses electricity to keep the temperature low, about 0°C to 5°C.
• Effect: the cold slows the bacteria and fungi that cause rotting.

Cold room

A cold room is a large, walk-in cooled room for storing produce in bulk, used by vegetable exporters and supermarkets.

• How it works: it is like a giant refrigerator the size of a room.
• Benefit: a person can walk inside, and many crates of tomatoes stay fresh for weeks while the farmer waits for a good price.
• Problem: it needs a steady electricity supply and is costly to build and run.

What is the difference between a refrigerator and a cold room?

Both keep produce cool with electricity, but they differ in size and use.

How do the storage structures compare?

What are the simple rules for good storage?

There are three simple rules for good storage: cleanliness, dryness and ventilation.

1. Cleanliness: clean the barn or silo before new crops go in, because old dust hides eggs and young insects.
2. Dryness: grain must be bone-dry, and a grain that is soft and cannot be cracked between the teeth is too wet for a silo.
3. Ventilation: yams and onions need moving air, because still air gets warm and the crop “sweats” and rots.

Classroom discussion

• Question 1: where do you keep onions at home?
• Question 2: where do you keep yams at home?
• Question 3: why do we not put yams in the refrigerator?
• Answer to question 3: yams are bulky and are damaged by very low temperatures, so they keep better in the natural air of a barn or a cool, dark corner.

Evaluation

1. What is storage, and what is post-harvest loss?
2. Describe how a barn works. State one benefit and one problem.
3. Why do pests like weevils die in a silo?
4. What is the difference between a refrigerator and a cold room?
5. List the three simple rules for good storage.

Assignment

Choose one storage structure from this lesson. Name two crops that can be stored in it, and explain one benefit and one problem of using it.