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Fertilisers

Environmental Issues.

Nitrogenous fertilisers (fertilisers containing nitrogen)
are applied in large quantities to promote plant growth.

The advantages are obvious,
with taller, healthier plants giving a higher yield from crops,
and therefore cheaper, more plentiful food.

Disadvantages begin when heavy rainfall runs from the
surface of the soil, taking fertiliser into streams and rivers.
This happens most when
1) Rain occurs soon after the fertiliser is applied to the crop.
2) Too much fertiliser is added to the crop.                           

Fertiliser in the river water increases plant growth
just as it does on land.
River plants and algae grow rapidly (called eutrophication),
and eventually die in large numbers.
Bacteria feeding on the dead plant material
use up the oxygen in the water.
Fish may then die through lack of oxygen.

Also, too high a level of nitrates in drinking water
is a health hazard, particularly for infants.
Nitrates can interfere with oxygen transport in the blood.

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