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- Our soil is now about as saturated as it is likely to get this year. Sure we will get
more rain but we will also get fine days and the drying out commences. Now is the optimum
time to improve your drainage and condition that heavy clay that passes as soil in this
region.
- You may think that it makes sense to add sand to condition soil, but think again before
you commit that folly. It would take at least 5 times the volume of sand to clay to make
an impact. If that seems a reasonable proposition, then you must own a sandpit some where.
No, adding sand is not an option.
- In this region we add a fine cream powder called gypsum. Never add dolomite, even if the
Mancunian and Mercurial Mr Cundall and ‘Backyard’ Don encourage you to. They are
talking within their understanding of eastern soils that are fairly acidic in reaction.
Add dolomite in Adelaide and your soil is doomed to make most of your garden go a bright
yellow, from lime induced chlorosis.
- Gypsum is hydrated calcium sulphate, which is a plentiful and naturally occurring
compound in this state and it is pH neutral when added to our alkaline soils. It has the
action of causing clay particles to aggregate and form ‘bigger lumps’ if you
like. Water engineers use the term flocculation, when they separate the turbid clay
particle from our water in the filtration process. Well gypsum acts like a soil
flocculent, improving drainage in the process.
- Gypsum also works in a short space of time and you do not need to dig it in, but it is
best spread on rough dug soil. Spread it at the rate of 300 grams per square metre on
heavy clay or 150 grams per metre on clay loam.
- I add composted organic material at the same time, which saves one lot of digging.
Don’t dig the compost in too deep and make sure you add some blood and bone or blood
meal, if you follow me, so that you don’t suffer short term nitrogen draw down. The
compost acts as a great nutrient buffer latter in spring, when you won’t be able to
dig, because the garden beds will be full of veggies and flowers.
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