PLANNING
From page 18
over the Internet or, if your
investment in growing crops is
substantial it will be worth
having your soil professionally
analysed by a laboratory. This
is especially true if you wish
to identify missing trace
elements such as boron,
magnesium etc which may
need augmenting to ensure a
good crop. That's because the
shop-bought testing kits
typically only have four tests,
namely for pH (acid or
alkaline), and the three main
plant nutrients, nitrogen,
phosphorus and potassium
(N, P & K).
If your beds are small, one
test of each type should be
sufficient. However, if your
plantings are extensive you
will need to do multiple tests,
over the whole area to be
planted, because soil content
can vary greatly in different
areas. Thus, draw a rough
plan of your planting area or,
more accurately, use a Google
Earth image of your plot.
Demarkate the field to be
planted and plot four, say, soil
sampling sites, A, B, C & D, a
few metres in from the four
corners of the field, marking
each sampling site with a
stake.
Next, take soil samples
according to the instructions
in the testing kit, carefully
noting which sample came
from where, and carry out the
tests, noting the results for
each area. In most cases this
is made easier for you by the
testing kit itself which will
require you to mix up a
sample of soil and water of,
say, a litre. You then perform
all the tests using fluid from
this sample, discard the
remaining fluid, rinse the
mixing container and the test
kit vials, and proceed to the
next location to dig up the
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required soil for the next
mixture.
If any of your tests are
abnormal in any way ~ either
very high readings or very
low, or at great variance from
the other tests in the field,
repeat the tests using a fresh
soil sample drawn from
somewhere a metre or so
from the original sample site.
Similarly, if, say, one corner of
your field is markedly more
acid or alkaline than the rest,
or shows a marked deficiency
in one or other nutrient,
perform a series of tests into
the centre of the field to see
at what point the soil
abnormality ceases.
In this way you can plan how
much of each remedial
treatment needs to be added,
and where.
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