|Better Farming Series 15 - Cereals (FAO - INADES, 1977, 51 p.)|
|Growing cereals in the modern way|
Soil must be protected against erosion
When a field is cultivated, the soil is often left bare. When it rains very hard, the water flows fast, and carries away the good soil. This is erosion. The soil becomes less fertile, and afterwards the harvests are less good.
When the ground is on a slope, you must till and make the rows across the slope, that is, on the contour lines. By this means the water will not flow so fast, and the good soil will not be carried away.
When the slope is very steep, terrace farming is used. You build little walls of earth or stones to hold back the good soil. In some mountainous regions there is a lot of terrace farming.
If the slope is not too steep, you can make ditches along the contour lines, or barrier strips, or ridges.
(See the first- year course on the soil).
· The soil must be protected against the sun.
When the sun is too strong it badly damages soil that is left bare. The sun quickly destroys the organic material in the soil. The soil loses its humus and becomes less fertile.
Bare soil must be covered. You can sow cover plants on land left fallow. For some crops you can use mulches which cover the soil and enrich it with humus.
· The fertility of the soil must be conserved.
To conserve soil fertility, crop rotation is used. Crop rotation means growing a different crop each year on the same field.
Why do we do this?
To feed, plants take different quantities of mineral salts from the soil. Different plants have different needs.
They take the mineral salts at different depths in the soil because they do not all have the same root system.
With crop rotation, the plants can use all the mineral salts in the soil and are better nourished. The soil does not get so poor.
For example: after groundnuts grow sorghum. Groundnuts and sorghum do not have the same root system, and they have different needs.
An example of crop rotation is: yams; cotton; rice; groundouts.