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close this bookBetter Farming Series 04 - The Soil: How the Soil is Made up (FAO - INADES, 1976, 37 p.)
View the document(introduction...)
View the documentPreface
View the documentPlan of work
View the documentWhy we study the soil
close this folderDifferent kinds of land
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View the documentThe soil
View the documentThe subsoil
View the documentThe parent rock
View the documentExamples of different soils
close this folderWhat is soil made of ?
View the document(introduction...)
close this folderSand
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View the documentSandy soils
close this folderClay
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View the documentClay soils
close this folderSilt
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View the documentSilty soils
close this folderHumus
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View the documentWhat humus does
View the documentSome practical advice
View the documentAir in the soil
close this folderWater in the soil
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View the documentCirculation of water in the soil
View the documentPractical advice
close this folderLiving creatures in the soil
View the documentEarthworms
View the documentRats and other animals
View the documentTermites
View the documentOther insects
View the documentMicrobes
View the documentSuggested question paper

Microbes

We saw that there are very many microbes in the soil.
Some microbes change organic matter into humus.
Other microbes bring nitrogen to plants.
We know that leaves get carbon from the air (see Booklet No. 2, page 21).
There is also nitrogen in the air. To grow, plants need nitrogen. But leaves cannot take nitrogen from the air.
In the soil there are microbes that can take the nitrogen in the air for their own food.
When these microbes die, they remain in the soil and decompose.
The microbes' nitrogen is changed into mineral salts.
The roots of plants can absorb these mineral salts through their root hairs (see Booklet No. 1).
Everywhere in the soil there are microbes that Can take in nitrogen.
Some of them gather on plant roots where they form little beads, or nodules.
The microbes in these little beads bring nitrogen to the plants.
Not all plants have these little beads.
They are found only on plants of the legume family.
Groundnuts, Dolichos bean, Crotalaria, beans, peas, Stylosanthes are all legumes.


Groundnut plant