FARMERS are cultivating soils that contain more genes than their own chromosomes do.
The world's first attempt to unravel the genetic code of three Australian soils has shown each contained up to 3000 bacterial species, representing a total of six million genes.
By contrast, humans have just 23,000 genes.
The soils were tested under a $3 million Victorian Government joint research project with the J. Craig Venter Institute, in the US, which first mapped the human genome.
The soil results are yet to be fully analysed, but Victorian researchers were stunned to find out how few bacterial species the three soils shared in common.
Only 10 per cent of the 3000 bacterial species found in a cultivated soil at Manangatang were also found in a soil just 200m across the road, in undisturbed Mallee scrub.
"Each site has the same number of species, but the species within the mix were so different," Department of Primary Industries soil researcher Pauline Mele said.
"It shows there's as much diversity in the cultivated soil as in the remnant soil."
The results raised questions about the origins of the huge number of bacterial species found in the cultivated soil that were not found in the remnant Mallee soil, Dr Mele said.
"Were they introduced? Did they evolve?" she asked.
Ultimately the DPI team, in partnership with the Vic AgBiosciences Centre, at La Trobe University, hopes to develop tools farmers can use to assess the productive capacity of their soils.
"We can see the day when farmers send soil samples into labs for a DNA diagnosis," Dr Mele said.
The Venter Institute analysis has shown DPI researchers the types of genes in the three soils and their similarity to other, well-known, bacterial genes.
The Mallee soils contained tough microorganisms belonging to a whole new domain of living creatures called archaea, which can endure environmental extremes such as the ocean depths and boiling thermal springs.
Dr Mele said the discovery of these organisms in the Mallee soils probably reflected their ability to deal with intense light and heat.
"Australian soils can be quite hostile," she said.
"They're also interesting because we're now finding they're involved in nitrogen cycling."
The third Victorian soil analysed by the Venter Institute, from an Ellinbank dairying paddock, had more in common with a US grassland soil than with the Mallee soils.
The Ellinbank soil shared less than 5 per cent of the bacterial species found in the Mallee soils.
Of the six million genes found in the soils, about 65 per cent have known functions, ranging from nitrogen fixation to making phosphates available to plants.
But the function of 35 per cent of the genes are still unknown, raising the possibility of finding new biological tools and chemicals for farmers.
