9 May 2007:
Australia – an ancient continent where good
soils are in very short supply – is about to discover a new
industry: making soil.
The new artificial soils will be made from wastes
which other industries and sectors – including manufacturing,
farming and urban waste – now throw away.
The key ingredients of a good soil include stable
minerals and organic compounds that give it structure, porosity and
fertility, says Professor Dick Haynes, who is heading up a major
new research effort by CRC CARE to create soils.
“While you can buy bags of ‘soil’
at the garden centre today, they mostly contain composted green
waste, which soon breaks down, subsides and eventually
disappears,” he explains.
“There is no scientific standard for soil as
such – no formula for making it. Everyone has their own
secret ingredients. Worldwide, very little research has been done
into how you make a soil. Our aim is to come up with
one.”
Furthermore, he says, some of Australia’s
biggest waste challenges – 13 million tonnes of fly ash from
power generation, an even larger amount of ‘red mud’
left over from bauxite processing, plus millions of tonnes of
bio-solids from urban sewage systems – are all potential
ingredients in artificial soils.
“At the moment people are paying to get rid
of these things. At CRC CARE we think we can formulate them
into something useful which is currently in short supply and
becoming quite expensive – new topsoil,” Prof. Haynes
says.
Two of Australia’s greatest headaches are its
millions of hectares of acid and sodic soils, both of which limit
food production. The ability to improve acid and sodic soils
could greatly increase the nation’s capacity to grow
food.
“Wastes such as power station or sugar
industry fly ash can be highly alkaline and could be used to
correct acid soils. Organic wastes such as chicken litter are also
highly alkaline and could be used to add nutrients as well as
correct acidity. Furthermore we think that – unlike lime
– they will leach further into the soil profile, correcting
acidity to a greater depth.
“Australia has millions of hectares of sodic soils –
rich in sodium. To amend these you need a soil improver high in
calcium, such as poultry waste, certain fly ashes or slag from
steelmaking.”
Part of the key to successful soil-making is to
avoid the high costs of transporting either the raw materials or
finished soils around the country – this involves identifying
wastes available locally which could go into a soil or soil
improver.
Another original twist is CRC CARE’s plan to
use certain industrial wastes to clean up other contaminated
wastes.
“Many of these substances, like red mud, fly
ash and slag have a very high adsorptive capacity. We can
literally use them to mop up heavy metals or organic contaminants
from other wastes, rendering these safe to use as soils, building
materials or other products.”
Professor Haynes says the growing interest in
soil-making is causing people to reappraise what they once regarded
as contaminated wastes, fit only to dump. Opportunities to invest
in the CRC CARE soils research program are still open.
“You could well be looking at the ingredients
for a major new industry. It’s even conceivable we
could re-import wastes from overseas industrial processes which
used Australian raw materials such as coal and iron, to turn them
into soils to beautify our cities or grow more food.”
Just as natural soils vary greatly, the composition
of artificial soils will depend on what is available and cheap
locally, from agriculture, food processing, heavy industry, power
generation and urban waste disposal systems.
“There are hundreds of uses for these waste
products, provided we can standardize the way they are treated,
ensure they are completely safe and that their long-term effect in
the environment is a beneficial one. At present many of these
questions remain unanswered.”
Dick Haynes is Professor of Soil and
Environmental Science at the University of Queensland. He has
worked as a senior soil scientist for the NZ Ministry of
Agriculture and Fisheries and was until recently Chair of Soil
Science at the University of Natal in South Africa.
Contact:
Professor Dick Haynes, CRC CARE and UQ ph 07 5460 1352 or 0448 501
352
Email: r.haynes1@uq.edu.au
Kim Sinclair, CRC CARE communication, ph 08 8302 3933 or 0416 095
324
Kim.sinclair@crccare.com
