Agriculture Reference
In-Depth Information
soil conditions. Overly acid soils can be
corrected with the addition of ground
limestone or dolomite, while alkaline soils
can be treated with iron sulphate or sulphur.
potassium for stout cell walls to protect plants
from disease. These three together with other
mineral elements keep plants growing. There
are many books written on fertilisers alone,
and it is not the purpose of this topic to
examine them in detail. Suffice it to say, get
to know your soil and the nutritional
requirements of the plants you are growing.
Soil contamination
If all seems well with your soil, with the
texture, structure and pH suitable for your
selected plants and they still do not thrive, the
soil may have been contaminated. Old
industrial land may have a hidden residue of
heavy metals or some other contaminant that
will prevent plants growing. If you suspect this
but don't want to have an expensive
professional soil test, there is a quick and
cheap way of finding out. Fill a seedling
punnet with the suspect soil. Sow some radish
seeds (they are very quick to grow) and see
what happens. If the seedlings are deformed,
badly discoloured or other than healthy, your
soil may need professional testing. Soil
removal is the only option for badly
contaminated soil.
Fertiliser use can be problematic with
indigenous or recreated natural landscapes. It
is rare on this crowded planet to find a soil
that has not been altered by humankind.
Agriculture has enriched soils for the
preferred crops and introduced weed seeds
abound in most soils. Many Australian natives
abhor phosphates yet the farmland that is
being gobbled up by housing developments
was treated with superphosphate. This does
not usually suit the indigenous plants as they
have to compete with vigorous weeds and a
possibly higher level of nutrients (or a
particular one) than they require.
Establishing natural grasslands also presents
problems as they cannot compete with the
introduced grasses whose seeds are stored in
the soil. One solution is to strip the topsoil
and plant into the nutrient poor and almost
weed seed-free subsoil. If nutrient levels are
too low, they can always be boosted.
Buried rubbish in the form of old plaster or
batteries will also affect plants as soon as they
have made root contact. Dig down (carefully)
and you may find the source of the problem.
Feedthesoiltofeedtheplants
Depending on what you are growing, your
plants may need some added nutrition in
order to grow and fruit.
Chemical, organic or mineral?
Whether your fertiliser is sourced from a
factory or a farm, the nutrients it contains are
taken up by the plants in exactly the same
way. That is, they are taken up as chemical
ions that are dissolved in the soil solution.
NH
4
+
or NO
3
-
are the same for the plant
whether it is derived from cow manure or
manufactured crystalline salts.
Fertilisers supply nutrients to the plants so
that they have all the building blocks for
health and growth. The major three nutrients
are: nitrogen for vigorous leaf and shoot
growth, phosphorous for photosynthesis and
other chemical and hormonal functions, and
