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Australian Native Plants

soil ph

22 years ago

I have just had a cubic metre of soil delivered which I was advised was a "native mix". I checked the pH and it was about 10. Way high for most natives I would have thought. Appears to have some sort of manure in it.

What is the best way of bringing the pH down to a satisfactory level?

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Comments (12)

thad_huffman
22 years ago
In America we lime it..It will cool down with time......Thad
Robert_NSW
22 years ago
It depends on what has caused the high pH. I would ask the supplier to replace the stuff. Probably they won't, but it is inexcusable for them to supply a soil that is so obviously unsuitable for natives. You definitely should tell them. I am inclined to think they have given you a mushroom compost mix by mistake as that can have a very high pH.

Maybe because it is only a cubic metre you could throw in a packet of Iron Sulphate but it may not lift the pH enough. You could always throw another packet on if it is not but test it before. Iron chelate is too water soluble and is not likely to remain in the mix.

You can apply some Flowers of Sulphur as it will be more permanent than Iron Sulphate. However Flowers of Sulphur will take some time to break down to the sulphate. Flowers of Sulphur is just the yellow powdered Sulphur.

Do not ever indulge in using acids of any sort as you will have no control over how dramatic the reaction will be.
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popi_gw
22 years ago
Hi Matthew

I agree with Robert, phone the supplier and talk to them about it, could well be mushroom compost. They will probably deliver the correct mix for you.

That was clever doing a pH test.

Popi
Rose_Qld
22 years ago
I'd speak to the supplier, 10 is way too high for exotics also surely. It's my understanding that lowering pH is more difficult and more expensive than raising it.

It's taken quite a few years for a bad batch of so-called soil to come good here, sea water contaminated river sand thought to be the problem.
User
22 years ago
Gee they do things strange in the USA to the soil
I put Lime in to raise my PH not lower it.

And Matthew I have to agree it is possibly mushroom compost as I got a load from the mushroom farm fresh last year and I tested it before spreading it around it was nearly 10 so I just left it, for a few months and only added a small lot to a barrow load of soil.

Do as Robert said, and ring the supplier too as I doubt anything would grow in that.
artiew
22 years ago
A ph reading of 10 is, to put it bluntly, ridiculous.

I firmly believe that a lot of landscaping supplies people (and, sadly, professional landscapers) view natives as 'second-rate', and this particular supplier obviously felt that natives would grow in any old mix - after all, he's seen them hanging on for dear life by the side of the road in drought and flood alike ....

Mentioning natives in many parts of Australia is akin to telling a pet store owner that your dog is a mixture of 2 or more different breeds - you'll get a patronising look followed by a quick 'is that the phone ?'. They will still gleefully take your money, but dont expect too much in the way of real service.

There *are* exceptions - people who are passionate about our flora - but its a case of sifting through the chaff to find the grain, and there is a lot of chaff out there.

Alternatively, we could all plant identical, squared off formal gardens filled with Buxus, Lavender and Camellias......... Wouldn't want to get any soil in the back of the Range Rover though, so I'd better get that fellow from the Yellow Pages to come out and give me a 'free appraisal' :)
matthew_72
Original Author
22 years ago
Thanks for the advice. I think that i will definitely check with the supplier. May have been an innocent mistake. Either way I shant be planting anything in it for a while!
flytower_au
22 years ago
According to Gwen Elliot there are some natives that like a high Alkaline soil, and most enjoy above 6.5 But she also says its almost impossible to bring the level down when it is as high as you say.She does give a list of about 30 plants that will grow in high alkaline soils. Her book Australian GArden,the Essential Gardener's guide is very informative. Good luck. I agree with the others get back to the supplier.
aus_tony
21 years ago
Just a warning to all. I have never tested soil in the past, but got a load of Native Low P mix on the weekend which tested 3 times at around 8 to 8.5.

Thought I was doing something wrong and so tested my sandstone filled garden sections which were 6/6.5 and some good old local soil (Nth Ryde) on clay 6/6.5

Rang supplier - who will remain nameless until they respond with their reasons - and not a tingle back since then (now three days).

So beware - I think I will go and test before delivery from now on.

Anyone know what to do with a pile of sandy high alakaline soil ?
nathanhurst
21 years ago
You could try mixing a few loads of tip mulch into your dud batch - rotting organic matter seems to acidify soil, as does high rainfall. Otherwise I would get the company to take it back and get a complete refund (you have to discourage them from thinking they got away with it).
aus_tony
21 years ago
Hey Nathan

Alright for you with your local tip supply :-)

Here in Sydney they charge you to dump green waste and then sell it back to you through the nurseries !

Thanks for the thought
Araucarias_Dad
21 years ago
pH of 10 in manufactured soils is not as strange as it sounds as suppliers will add Lime to counter act the acidity of composted manures et al. Generally, quality assurance is difficult for suppliers when volumes are large, however the way to lower a pH in a soil is through the application of either Sulphate of Ammonium, Blood and Bone or Urea.

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