Swan Coastal Plain

If the parent material contains carbonate, the soil starts life with a built-in supply of the very thing we're spreading out on our paddocks.

The limestone under much of the Swan Coastal Plain was originally calcareous sand blown in from the continental shelf during times of low sea level, and it's mainly shells and coral.

And soil sitting in close contact with that limestone carries a large calcium component in the exchange complex, the negatively charged surfaces on clay and organic matter that hold onto nutrients and give a neutral reaction.

So some country is alkaline because of what it's made of, and no amount of management made it that way.

Now, one thing worth knowing, this is not fast, and it is a feature rather than a fault.

Lime is not very soluble, so it sits in the soil and it keeps reacting as acid keeps being produced.

On the Swan Coastal Plains soils, a single application was found to be effective for about 10 years, and the response threshold on those soils was a PHCA below 4.2. you're not applying a treatment.

You're installing a reserve and a bonus that surprised me.

Beyond raising the pH, lime also increases soil moisture retention.

We're at the sort of western and, if you like, northern limit of Kerry and you get the southern wetlands there.

And there's the Swan Coastal Plain, which is basically the coastal section all the way down the coast from way north of Perth right down to here.

So we're on the limit.

We're this little bit stuck out into the Indian Ocean.