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A Handbook of Biology

RØLËS ØF SØÏL:

It supplies

minerals and

holds water.

It harbors

nitrogen-

fixing bacteria

and other

microbes.

It supplies air to

the roots.

It acts as a

matrix that

stabilises the

plant.



Deficiency of essential minerals affects the crop-yield. So, fertilisers

should be supplied. Both macro-nutrients and micro-nutrients form

components of fertilisers.

MËTÅBØLÏSM ØF ÑÏTRØGËÑ

ÑÏTRØGËÑ ÇÝÇLË

Nitrogen is the most prevalent element in living organisms.

Plants compete with microbes for the limited nitrogen in soil.

Thus, nitrogen is a limiting nutrient for natural and agricultural

eco-systems.

The process of conversion of nitrogen (N2 or N ≡ N) to ammonia is

called nitrogen fixation.

In nature, lightning and UV radiation provide energy to convert

nitrogen to nitrogen oxides. Industrial combustions, forest fires,

automobile exhausts and power-generating stations are also

sources of atmospheric nitrogen oxides.

Decomposition of organic nitrogen of dead plants and animals into

ammonia is called ammonification.