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close this bookBetter Farming Series 19 - Market Gardening (FAO - INADES, 1977, 56 p.)
close this folderOnions
View the document(introduction...)
View the documentPrepare the soil well
View the documentSow in nursery beds and transplant
View the documentProtect against insects and diseases
View the documentHarvesting
View the documentSuggested question paper

(introduction...)

74. This is a vegetable which sells well.

But onions do not grow very well in moist regions; they grow better in a dry and hot climate.

Leeks, garlic, and shallots are grown in much the same way as onions. They are attacked by the same diseases. They need the same soil and the same care.

Prepare the soil well

75. Onions develop the end of their stems underground. This part of the stem which fattens in the earth is called the bulb.

The bulb grows quickly and becomes large if the soil is light, not too moist, rich in humus and free from weeds.

76. The soil must not be too moist

If the soil is very moist, the bulb may rot. In a well- tilled soil, the water goes down deep and air can get in.

So till the soil deeply.

77. The soil must be rich in humus.

It is best to grow onions after salad plants. Salad plants do not use all the mineral salts in the soil. Onions use up the salts that remain from the manure you put down for the first crop.

Apply fertilizers. Onions need above all potassium and phosphorus. Sulfur is often very useful too.

Ask the supplier or the extension services how much fertilizer to apply.

Do not apply too much nitrogen, otherwise the leaves will develop more than the bulbs.

Never grow two crops of onions one after the other, because of diseases.

Sow in nursery beds and transplant

78. Some market gardeners have large onion fields. To sow in nursery beds and to transplant later means a lot of work. These market gardeners do better to sow their onions in open beds.

Many market gardeners have small onion fields. For these people it is better to sow the onions in nursery beds and to transplant them.

Do not sow seeds which are more than one year old.

Sowing in open beds

79. Leave 25 to 30 centimetres between rows and, along the rows, 6 to 8 centimetres between plants. You will need 4 kilogrammes of seed for 1 hectare.

Sowing in nursery beds and transplanting

80. Disinfect the soil of the nursery beds. The soil should have a fine filth and be firm in depth. Leave 10 to 15 centimetres between rows.

Make a shelter and water the beds twice a day. Thin out surplus seedlings and weed.

When the seedlings have grown to a height of 15 to 20 centimetres, take them out of the nursery beds and transplant them into new beds. Leave 20 to 30 centimetres between rows and, along the rows, 10 to 15 centimetres between plants. Set the plants only 2 or 3 centimetres deep In the soil.

Pack the earth down well around each plant. Water. If any plants do not grow, replace them with seedlings you have kept in the nursery beds.

Do not earth up the onion plants when you cultivate; if you cover the bulb with earth, the bulb does not grow well.

Protect against insects and diseases

81. Insects

Insect

Treatment

Onion eelworms: Tiny worms which attack the roots and the base of onion plants

Pull up and burn infested plants. Disinfect the soil with boiling water, or with Vapam or Nemagon. Good crop rotation.

Onion fly: Its maggots eat the bulbs, and the bulbs rot

Control the maggots by treating the plants with Aldrin or DDT.

82. Diseases

Disease

Treatment

Onion smut: Seedlings do not grow well; black or grey lines appear on the leaves

Disinfect the seeds. Disinfect the soil with Formol or Thiram

Downy mildew: Yellow spots appear on the leaves. The whole plant becomes yellow and dies

When the mildew appears, treat onion plants with copper based products, or with Thiram, Zineb, or Ziram.

Rots: These are due to funguses which attack onion seeds, destroy the roots and bulbs of seedlings, cause the leaves to wither and kill the onion plant

Control rots by disinfecting the soil with boiling water, or with Formol.


Later, treat onion plants with copper-based products, or with Thiram Zineb or Ziram

Harvesting

Onions should be harvested only when they are quite ripe.

83. An onion is ripe when the leaves are dry. An onion harvested before it is quite ripe does not keep well.

Lift onions only when the leaves are quite dry. It is best to lift your onions when it is not raining, so that they will not rot.

Leave the onions Iying on the field for a few days, so as to dry them well. It is best to cover them up with a little grass or straw. If it rains, dry the onions under a shelter.

To keep onions well, store them in a dry, airy place, well protected against rats and other animals.

Suggested question paper

UNDERLINE THE RIGHT ANSWER

Pimento and gumbo are leaf vegetables

Yes or No

The market gardener should buy selected seeds every year

Yes or No

The vegetable garden should be as far as possible from the house

Yes or No

Thinning out weakens the vegetables

Yes or No

A good market gardener should add well-decomposed manure to the soil of his vegetable garden

Yes or No

Well-packed vegetables do not sell well

Yes or No

FILL IN THE MISSING WORDS

When somebody grows ................ mainly for his family to eat, this is called ...............
Vegetables add to the diet many .......... and above all many ........
If the field is on a slope, lay out the.........across the slope.
To prevent a disease attacking all the plants in the vegetable garden, the farmer must .........and ............ all the diseased plants.
Snails ............the stems and leaves of vegetables: they must be .........often.

ANSWER THE FOLLOWING QUESTIONS

What is the purpose of crop rotation?

Why must the soil be well tilled before sowing?
What is a nursery bed? Name two vegetables which have to be sown first in nursery beds.

Why is frequent cultivating necessary?

Why is it necessary to mulch the soil and to make shelters for the vegetables in the vegetable garden?

Describe how to disinfect the soil of a vegetable bed.

What should you do when you see snails and insects on the vegetables in your vegetable garden?

By what means can you improve the fertility of the soil in your vegetable garden?

Have you tried to make compost for enriching the soil of your vegetable garden? Describe how you did it.

Make drawings to explain better.