Soils aint soils…

Hakea orthorrhyncha

Hakea orthorrhyncha

…to misquote an ad of some years ago! Where I live in the Mallee area of South Australia, the soil is very poor and the rainfall is low. So when it rained on the north coast of New South Wales last week, the amount of rainfall was incomprehensible. 14 inches (350mm) in a day at Bellingen, inland from Coffs Harbour! That’s more than we get in an average year.

I measured the pH of the soil at a number of locations over our 5 acres (2 hectares). Is it any wonder the fruit trees have not done as well as I had hoped. The pH is 8+ to 9+ which is highly alkaline. The quality of the soil varies from sandy loam, to limestone rubble to non-wetting mallee sand. There used to be a strawberry farm on our property, so the structure of the soil is not too bad at all.

My usual reaction to someone who says “that won’t grow on your block of land” is to attempt to prove them wrong. I don’t think I am alone! A lot of plants grow very well in alkaline soil. Some plant species will grow reasonably well, but do not achieve the ultimate size. Others sit and “sulk”, and others struggle to maintain good leaf coverage. Of course some of the most desirable plants (in my eyes) are the ones that are native to areas of acid soil! It is amazing how adaptable Australian native plants are.

When I began writing this piece I wondered if I really understood the science behind pH of soils, so I detoured to find some more info. I am glad I did. I realise that I should have been using iron chelate or iron sulphate more diligently on some plants and would have far better growth by now. Some homework to do later this week.

For more information on soil pH see the ASGAP web page Understanding Soils and Nutrients.


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