If somebody was to tell you that you could substitute your synthetic phosphate and nitrogen fertilisers with a free replacement you'd tell them they were talking crap. And you'd be right - but not for the reasons you'd expect.
Trials conducted using processed human waste products, euphemistically dubbed bio-solids, has found that the treated product can be used in the same way as animal manures and can satisfy the nutritional needs of broadacre crops.
Best of all - it is free, with treatment plants giving the product away.
CSIRO scientist, Mike McLaughlin, who has been working on research into the use of bio-solids as fertiliser, said farmers in some States were catching on.
"They are really digging into the stockpile in WA, SA and NSW but there is scope for more usage in other States such as Victoria."
Professor McLaughlin, who is based at Adelaide University, said that bio-solids have much lower rates of nitrogen and phosphate than conventional synthetic fertilisers but could be spread on in bulk to provide all a crop's nutritional needs.
"Bio-solids only have between 1 and 4pc nitrogen and 1 and 3pc phosphate but they can be applied with a muck spreader prior to sowing at rates of between five and ten tonnes to the hectare and that will provide all a crop's needs for one year and most of the amount required for the following year."
In the work conducted by Professor McLaughlin, he said crops in the north, such as sorghum and cotton, have shown good results with the application of the waste by-product while he was confident that cereal and oilseed crops in southern Australia would also respond well – saying that many trials were drought-affected.
Aside from that, Professor McLaughlin said that unlike some synthetic fertilisers, bio-solids also provided most of the trace elements necessary.
"The one thing you might wish to mix in is a little potash, because the product tends to be low in potassium," he said.
With 300,000 tonnes of bio-solid available annually, there is scope for human waste products to make a significant niche market within the fertiliser industry but there are drawbacks.
Professor McLaughlin said that usage would be limited to where the product could be economically freighted.
"It is free but it is bulky to transport and farmers will also have to pay the cost of spreading, so it won't be for everybody."