Land and Water Link

Issue No. 12, May 2002

Working Towards Sustainable Soils What is the role of soil biota in sustainable soil function? Dr Steve Rogers from CSIRO Land and Water and Dr Matt Colloff from CSIRO Entomology are developing molecular diagnostic tools to determine condition of soil biological activity so that we can assess the impacts of land management on ecosystem function. Sustainable use of soils is being held back worldwide by the lack of a simple test that can tell farmers and other managers whether the land in their care is improving or getting worse. ccording to Steve Rogers and Matt Colloff, the answer lies in the soil – or at least in the billions of micro-organisms and natural chemical processes that control how the soil functions, and whether it becomes richer or poorer. What's been missing until now is the ability to look at the 'big picture' – to see how these billions of different microbes combine to unlock the nutrients and elements vital to plant life and fertility, and how well they withstand shocks caused by human intervention or mismanagement. 'We know what's in the soil – we just don't know precisely what it does, how all these creatures interact, exactly how they combine to recycle nutrients and energy within the soil, in the form of carbon, nitrogen, phosphorus and sulphur and make them available to growing plants', Dr Colloff explains. The solution was to look not at the microbes themselves, but at something far more basic – at the genes within the microbes that yield the natural chemicals that unlock soil nutrients. Taking what resembles a 'public health' as opposed to 'individual patient' approach to soils, Steve Rogers and Matt Colloff are using off-the-shelf testing technologies to reveal the amount and diversity of key genes in micro-organisms in a soil responsible for nutrient cycling, and how active they are. The result, they hope, will be a suite of tests to analyse a landscape and tell whether it is improving, stable or degrading. For the first time, this should give farmers and other land managers a realistic measure of whether their management tactics are making the situation better or worse, at least so far as biological function is concerned. The team is using three trial sites across Australia – cane country and rainforest at Tully in Queensland, grazing land and Banksia scrub at Moora in Western Australia, and cropping country and native woodland in Victoria – to assess whether their genetic tests can provide consistent answers across a range of environments and management systems. The team expects that it will take about three years to demonstrate whether reliable soil gene tests can provide a practical test of soil health under a wide range of conditions.

Such a test would have widespread application. A mining company wishing to know whether its land rehabilitation program is really working or not, could find part of the answer by looking at changes in soil function. It could be used by a national park, state forest body or a tourism manager to preserve natural ecosystems in the peak of condition. Farmers, clearly, would find this approach invaluable as they experiment with more sustainable cropping and grazing systems, or compare one paddock's performance with another. It could even be used in cities to monitor the environmental health of parks, public gardens and reserves. With growing international trade pressure for producers of all sorts of products to demonstrate that their production processes are sustainable, the use of an effective test could give Australia a global trading advantage. This research is supported by Land and Water Australia. Dr John Curran, Deputy Chief of CSIRO Entomology (one of the partners in this work) is part of the C-Quentec PCC/CSIRO/Aventis/ SARDI Joint Venture Diagnostic Testing service.

For further information:

Contact

Dr Steve Rogers
CSIRO Land and Water
Ph: 08 8303 8407

Dr Matt Colloff
CSIRO Entomology
Ph: 02 6246 4354