Soil pH and how to Test it.

Just a short note on why you should start your gardening with soil pH test. You might even want to do this before you buy the house if gardening is going to be a big part of your relocation.

I was doing a pH test as part of a site and client review for a future Permablitz in Caramar, it might be a local blitz as part of the Northern APEs or we might widen it as a mail out invite to the wider Permablitz mail list. Anyway as well as interviewing the 'client', photographing and looking over the site I grabbed soil representative soil to do a pH test. I do this because the range of Perth Coastal Sands pH is huge, my backyard is around 8.5pH (very alkaline) and some swampy sulfate sands can be 4pH. Clearly this vastly impacts what treatment is required for the soil before any plants should be considered or planted. While we cant change the whole body of the soil in the yard, we can do at least three things, where possible choose plants naturally suited to the pH range, adjust the local soil in the tree (holes) and fertilise accordingly, and adjust and control or buy in the soil we intend to to the heavy vegetable gardening in.

Why is pH so important, this picture show the mineral availabilities to plants at varying pH's. Borrowed Amanda's pic from Daley's Forum. Thanks.














Back to the samples, well out came the standard close enough is good enough garden shop pH kit.














Thankfully Erika's soil sample was a great pH as you can see by the card and indicated colour on the soil.

While the soil is certainly lacking clay content (bentonite - water holding), organic matter and fertility it is at least a good pH to start with. pH is a sliding exponential scale that is the more the pH is above or below 7 the harder it is to bring it back to that point. Simply adding compost, clay and manure to what is still the majority sandy base will not correct mineral imbalances in pH's outside 6-7.5. Organic matter 'buffers' pH but doesn't effectively change it, generally the pH will decrease slowly with continual compost and manure feeding.

Now while I have the kit out, time to look at the pH of my more neglected beds, These have never received sulfur or iron sulfate to address the alkalinity, consequently things dont grow that well in those wicking beds. I was hoping after a year or adding sheep manure and growing plants that I might see 8 ish......

Bugger that purples so bright my daughter would love it. looking closer to 9 than 8. To address this is a major issue, and if I dint not have wicking beds (closed nutrient/water systems) I dont think I could, without physically replacing 70% of the soil. Given the wicking beds can hold my sulfur treatments instead of having them leach away every time I water I shall have a crack at reducing this pH and setting up the soil again and report my findings.


One things for sure elevate pH will not sort itself out magically.