Agricultural
3 April, 2026
What is it about the soil around here?: Black Alluvial Soil
We all know that the soil around here is dark, magic for growing things and really sticky when it gets wet. But what is black alluvial soil, how is it formed and where else is it found? We deep dive into what makes this ground so good.
Little green sprouts shoot up out of it, shimmering in a breeze.
When it’s dry, it cracks like the desert, when it’s wet, you could almost take a whole paddock home.
Soil that cracks is called vertosol, meaning it’s clay rich, hence why it gets so sticky.
Black alluvial soil is a big part of the reason Clifton was once known as the ‘million-bushel wheat district’.
Black alluvial soil is a soil rich in organic matter and iron.
Millions of years ago basalt sediments from volcanic activity across the Great Dividing Range was deposited across much of what is now the Darling Downs by the Condamine River and its many off-shoots and estuaries.
It’s formed through a process called pedoturbation, the gradual mixing and therein changing of a soils composition.
More clay, less clay, new soil mixing with old, high nutrients with low nutrients soils.
This is done through the freezing and thawing of soil in cryturbation and the manual moving and mixing of soil done by organisms, such as worms or burrowers.
This is part of the reason why, based on the soil alone, its so hard to date the composition of soil on the Darling Downs.
However, depending on the area, it can take between 200 and 400 years for black alluvial soil to naturally form.
Nonetheless, we can still understand it.
Black soil is a gold mine.
The high humus, organic component of soil, is what makes black alluvial so fertile.
Decaying animals and plant life are absorbed and their nutrients, like calcium, magnesium and potassium, retained for longer.
That, and black alluvial soil also holds onto water incredibly well.
Black alluvial soil is also easy for roots and organisms to penetrate, increasing its pedoturbation and its absorption of new nutrients.
Fertiliser and compost are ways in which humans make soil more nutrient rich artificially.
Nutrients is what helps crops grow.
That’s why 79 per cent of Queensland’s cereal crops and 29.6 per cent of broadacre crops are grown in the region.
Indeed during its time as the ‘million-bushel wheat district’ Clifton was thriving off what was grown out of the sticky, black soil.
It does however come with draw backs.
Dairy farmers need to be extra careful, as the high amount of organic material means there’s a high chance of mastitis for their cows.
Dairies on black alluvial plains have to keep their cows clean.
Nor will black alluvial soil hang around.
Erosion happens at a rate of about 0.2 - 0.3cm a year.
This can be spurred on by soil pollution, water logging, soil compaction, and biodiversity loss.
Other regions around the world with black alluvial soil include the Deccan Plateau in India, the Pampas in Argentina, the Great plains of the U.S. and Canada, stretching between Manitoba all the way down to Texas.
Wherever we find black alluvial soil, there’ll be farms and farming communities.
There is also the black alluvial soil of the Eurasian food bowl, stretching from Ukraine to Siberia, down into Kazakhstan and stretching across Russia.
The large stretch of the black, sticky gold is called černozëm or Chernozem Russian for ‘black soil.’
It’s also known in the region as ‘black gold.’
It’s the reason why the Ukraine War has put such a strain on global trade, particularly wheat.
Twenty-seven per cent of the world’s wheat and 23 per cent of global barley exports come from either side of the war; Russia and Ukraine.
The great expanse of Chernozem, black soil, which makes up 65 per cent of Ukraine, is the land that is being fought over, as it has been for thousands of years.
In Ukraine in 2011 the black market for Chernozem, sat at $900 Million USD, prices sitting at about
$80-100 per tonne in Summer and $100-150 per tonne in Winter.
An excavator would dig up the soil, a truck would deliver it, and phony soil would be deposited into the excavation.
In 2021 the South China Morning Post reported that local farmers dealing with financial hardship were selling the soil to survive.
Both black markets prompted restrictive legislation from their respective governments.
Closer to home, for anyone who’s thinking about getting out a spade and making a few dollars, while not inherently illegal, the sale, movement and contamination of soil is highly regulated.
Black alluvial soil is nowhere near as abundant in Australia, with the majority lying between Queensland and New South Wales.
Black alluvial soil does, however, cover one third of Queensland, which is quite a stark thought when you sit with it.
Because some volcanoes erupted millions of years ago, and left sediment for rivers to carry across a plain, we have the Darling Downs we have today.
It starts to seem as if it was some degree of a haphazard destiny that Clifton and the Downs would be known for its farming.
Also, given what’s going on in the world at the moment, the black soil, or black gold, is certainly shining bright.
It’s a gift in that sense, even if it is a pain to scrape off your boots.
This patch of dirt we call Clifton, the generations of farming that’s been done in its surrounds.
It was always going to happen, as long as humans were around to farm it.
No wonder the Darling Downs fell into the folklore and imagination of Australia’s first century.
For European settlers, who brought their farming backgrounds to the continent, it would have seemed like striking gold.
The wonderful, sticky gift is still Clifton’s, and as long as we respect and look after it, it’ll do the same for us.
