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close this bookBetter Farming Series 20 - Upland Rice (FAO - INADES, 1977, 30 p.)
close this folderUsing fertilizers
View the document(introduction...)
View the documentWhy apply manure or chemical fertilizers?
View the documentWhat fertilizers to use
View the documentOrganic manure and chemical fertilizers

(introduction...)

27. You are now ready for further progress.

If you use new tools and also apply fertilizers, you will be growing upland rice by very modern methods. You have seen how you can make good use of animal- drawn tools.

You can get a good harvest if you:

- till your field well

- sow well

- weed well

- cultivate a larger field,

You will find that you earn more money.

With the money earned from your crop, you can buy fertilizers

We shall now study how to use fertilizers so that you can earn a lot more money. If you use fertilizers, you keep the soil fertile or even make it more fertile.

Once you do that, you change from shifting cultivation to continuous cultivation.

Why apply manure or chemical fertilizers?

28. To get a good harvest

It you apply manure or chemical fertilizers to your rice field, the rice will tiller vigorously (see paragraph 25) and bear many grains: The yield will be good.

29. To keep the soil rich

Chemical fertilizers give back to the soil the mineral salts which the plants take out. Manure gives the soil organic matter. It makes humus and improves the soil structure.


To keep the soil rich

30. Chemical fertilizers and manure cost a lot of money.

They will not pay

- if you grow your crop on too steep a elope the mineral salts of the manure and fertilizers are washed away by water together with the soil.

- if you do not till the soil well because in badly prepared soil the roots cannot develop well.

- if you do not sow selected varieties because unimproved varieties use the manure and fertilizers less well.

- if you do not sow your seeds in rows and at the right time because plants sown too late will not yield so well.

- if you do not cultivate about 3 weeks after sowing and whenever new weeds grow because with fertilizers, the weeds grow better. If you do not remove them often, they may take a large part of the nourishment from the rice.

- if you do not rotate your crops correctly

After 8 rice crop, the soil will still have some of the mineral salts added by the manure and the chemical fertilizers. You must make the right choice of the crop you will grow on the same field after the rice. If possible, choose one that will use the mineral salts still in the soil.

The money earned from a good crop will easily pay for the fertilizers you need.

What fertilizers to use

31. Fertilizers are different.

- according to the crop rotation:

Plants do not all take the same quantity of each mineral salt out of the soil. Before sowing rice, you must therefore give back to the soil the mineral salts taken out by the preceding crop.

These mineral salts are contained in chemical fertilizers.

- according to regions:

The soils of different regions are often different; they do not contain the same quantity of each mineral salt.

For example, a soil very poor in nitrogen must be given a lot of nitrogen.

You can see that a soil is poor in nitrogen if the young leaves turn yellow.

Organic manure and chemical fertilizers

32. Organic manures are animal manure and green manure.

Organic manures improve the structure of the soil. Plants grow better in a soil of good structure, and the chemical fertilizers are used better.

Organic manuring should therefore be done at the beginning of the rotation, that is, before growing the first crop on a field.
For example

If in the first year after clearing the field you grow a crop of yams and the second year you grow rice, you must apply organic manure in the first year before you plant your yams.

33. Chemical fertilizers.

You know that the main chemical fertilizers are:

- Nitrogen (N)

- Phosphorus (P)

- Potassium (K)

Rice needs above all nitrogen.

The nitrogen fertilizer most often suitable for the soils of Africa is ammonium sulfate.

But rice also needs phosphorus and potassium. If the rice cannot take out of the soil enough phosphorus and potassium, the stems are not strong and so they bend down to the earth so that the grains cannot form and ripen well.

Ask advice from the extension services in your area. They will tell you how much fertilizer to apply to your rice field.

It is best to apply nitrogen, that is, ammonium sulfate, in three separate applications:

For example

It you have to give your field 100 kilogrammes of ammonium sulfate, apply:

- 40 kg before sowing,

- 30 kg after the first cultivation,

- 30 kg when you see the panicles are forming.

Be careful not to let ammonium sulfate, get onto the leaves; the fertilizer may burn them.

Phosphoric acid and potassium are applied before sowing.