Part 4j. Methods
of increasing food production and improving sustainability
Increasing the nitrate content of soil to increase soil fertility and crop
Doc Brown's Biology exam study revision notes
There are various sections to work through,
after 1 they can be read and studied in any order.
Sub-index of notes on increasing food
Index of notes on ALL aspects of food production
in which farmers can increase the nitrate content of soil
As plants grow they will use up the available
nitrates in soil, which can become deficient in essential nutrients. When the crops are harvested, the nitrate content of
the soil is now reduced - its ended up as protein in the grain. Unless the nitrate is replaced, the nitrate content
in the soil will decrease with each crop grown. To avoid the soil becoming infertile leading to poor
plant growth and deficiency disease, the nitrate must be replaced.
There are four ways of doing this.
(i) Spreading an organic fertilisers like
animal manure or some composted plant material which is decomposed by
bacteria/fungi to release nitrogen compounds into the soil. This is a good method
because it is essentially recycling organic substances from animal waste
or plant material, both returning nitrogen compounds to the soil on
Spreading synthetic fertilisers (e.g. NPK products) made from ammonium
and nitrate ion compounds.
Can you name them?
However, the use of artificial fertilisers can
create pollution problems like eutrophication if overused. See the notes
Biodiversity, land management, waste management,
maintaining ecosystems - conservation and
already mentioned in Part 4b.
(iii) Crop rotation avoids growing
the same crop in the same field over and over again. Several different
crops are grown each year in a seasonal cycle. The cycle should
include a leguminous plant (nitrogen-fixing crop) like beans or peas that will
return nitrates to the soil for another crop the following year -
the plant itself can also be ploughed into the field.
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