We saw that there are very many microbes in the soil.
microbes change organic matter into humus.
Other microbes bring nitrogen to
We know that leaves get carbon from the air (see Booklet No. 2, page
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
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.
found only on plants of the legume family.
Groundnuts, Dolichos bean,
Crotalaria, beans, peas, Stylosanthes are all legumes.