Ways of improving soil fertility.
Fertilisers contain important nutrients
for plants to grow e.g. nitrates for nitrogen, phosphates for
phosphorus, ions of magnesium and sulfate (for sulfur) and
compounds of trace elements like
copper, zinc and boron.
The idea of using fertilisers is twofold:
(i) bring into use poor quality soil
deficient n nutrients,
(ii) replace nutrients
used up by the previous crops,
(iii) grow crops with increased yield,
(iv) although (i) to (iii) apply to
any fertiliser, naturally produced organic fertilisers
produce a much better quality of soil.
Organic farming with compost and
cattle muck produces much better quality of soil, whose
structure and nutrient and water retaining properties
are important.
BUT overuse of synthetic inorganic
fertilisers has created eutrophication
problems in lakes and rivers and they are not cheap,
particularly in the context of a poorer country.
Eutrophication is when an excess of
nutrients like nitrates and phosphates causes algal blooms, so
water is covered in a thick mass of green slimy algae that
reduces oxygen levels in water and kills most aquatic life
beneath it.
Manure and compost
Organic fertilisers based on plant and
animal waste are more beneficial for soil quality and probably
produce food of a higher nutritious quality.
See
The manufacture & use of fertilisers
and
NPK fertilisers-environmental problems
Infertile soils too acidic for growing
crops or raising cattle (pH <7), can be treated with alkaline
lime to increase the pH of the soil to a more neutral value (~pH
7).
