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Unfortunately, by the time these symptoms are obvious, extensive damage to the
crop has already occurred, causing in some cases considerable loss to the grower.
On the other hand, where insufficient fertiliser is present, plants do not grow at
the optimum growth rates. This requires the grower to hold stock longer before it
reaches marketable sizes.
The best method for monitoring soil salt levels is by the use of a conductivity
meter.
Collection of samples.
An important part of correct soil testing is to obtain a sample which is
representative.
A: Field samples.
Take samples from areas of poor growth.
1.
Using a spade, clear the growth from the top of the soil, being careful not to
remove any soil.
2.
Dig a small hole with straight sides.
3.
Take a 1 cm thick slice from the side of the hole to a depth of 15 cm (or 5 cm
for turf.)
If the subsoil occurs before 15 cm, take the sample from the top soil only.
4.
Repeat this process 10 times over the area to be checked.
5.
Mix all the sample together, and take about 1/2 kg as the test sample. Spread
the sample out on a piece of clean paper, and allow it to dry.
B: Samples from Potted Plants.
1.
Select 10 plants showing evidence of salt injury.
2.
Knock out the plants, and remove the soil from each pot.
3.
Mix the samples together well, then take 1/2 kg sample, and spread it out to
dry on clean paper.