Episode 6: Understanding Soil Texture. Sand, Silt and Clay and Why Size Matters

So what is soil texture and why does it matter everywhere? Well, let's start by defining it properly.

Soil texture is the relative proportion of sand, silt and clay particles in your soil.

It's the mineral building blocks of what soil scientists call the fine earth fraction.

And soil texture is described by using sand, loam and clay.

But the particle sizes that make up that soil texture are the sand silt and clay.

Please notice the swap.

Loam steps in, silt steps out.

Clear as mud? Okay, let's discuss this a little bit more then.

Here's what makes texture special.

It's an inherent property.

An inherent property means a quality or property that belongs to something as a natural, essential part of what it is.

It's built into the thing itself from the start, rather than being added or acquired or imposed later.

An inherent property is fixed and it's permanent.

It can't be changed by outside effort or management because as part of the thing's fundamental nature, in the case of soil, an inherent property like texture was set when the soil formed and stays essentially the same over a human lifetime.

No matter how much the land is managed, your pH can drift, your organic matter can build or decline, your compaction comes and goes with traffic and also with the season.

But texture is what your soil fundamentally is, set by the parent material it's formed from, its place in the landscape and thousands of years of weathering.

Short of physically carting sand or clay into a paddock, it isn't something changing in your lifetime.

That inherent property drives an astonishing amount of soil behaviour.

And this is true whether you're farming in the Western Australian wheat belt or the black soil plains of the American Midwest, a paddy in Japan or a field in Ireland.

Texture influences how fast water enters and moves through the profile, how much water is stored for the crop, how well nutrients are held against leaching, how much organic matter the soil can protect, how it handles machinery and how erodible it is.

Texture is one of the few soil concepts that is genuinely universal.

Every soil on earth has a texture.

Now WA does give us an unusually vivid classroom because our landscapes throw the full range at us.

Deep sands, sandy duplexes, ironstone gravels, loamy earths and heavy valley floor clays.

Sometimes even all in a single paddock.