AUSTRALIAN grain growers are playing a vital role in improving and preserving the health of the nation's arable soils through the adoption of research and development outcomes.
On the eve of World Soil Day (December 5), Grains Research and Development Corporation (GRDC) managing director John Harvey said it was timely to acknowledge the grains industry's efforts in ensuring the long-term fertility of soils, necessary for essential food production.
"Australian growers, supported by the GRDC, have for a long time recognised that healthy soils grow healthy crops," Mr Harvey said.
"That is why our farmers are world leaders in taking up new technology and adopting cutting-edge farm practices that promote soil sustainability."
Mr Harvey said World Soil Day was an opportunity to reflect on the contribution to grains production by the vital yet finite resource beneath our feet, as well as the contribution to protecting our soils by growers and the extensive advancements in research and development over the past decade.
"The GRDC, on behalf of growers and the Australian Government, has facilitated significant investment into understanding and improving cropping soils, which really are the engine room of grains production systems," he said.
"Minimum and no-till farming, retention of crop residues and improving ground cover are now widely adopted practices that have had a huge impact on reducing soil degradation.
"Our research into the soil nutrient and biological benefits of rotating crops has also enabled growers to reduce input costs while building better soil profiles."
Mr Harvey said the GRDC had in recent years increasingly turned its attention to the biological make-up of the nation's soils and their hidden potential to increase profitability and sustainability of grain production.
The GRDC's Soil Biology Initiative aims to equip grain growers with tools and resources for better management of nutrient input, suppression of soil borne diseases without chemicals or minimum chemical input, and improved information on what makes a "quality" soil.
"Productivity within the grains sector has been limited for the past 10 years so we need to explore all avenues for lifting growth," Mr Harvey said.
"The soil biological resource is seen as something of the 'last frontier' for the grains industry.
"We don't fully understand the biological composition of our soils and how they function and contribute to grain production, so there is enormous scope for developing some new thinking about how we should treat and manage our soils and the practices we can put in place to drive productivity and profitability."
This world-leading investigation into the influence of soil biology on crop yields is establishing an unprecedented foundation of knowledge and has unearthed some important insights that will inform growers' future farming practices.
Soil Biology Initiative co-ordinator, Associate Professor Pauline Mele, says scientists now know, for example, specific organisms exist in soils in the northern cropping region that can suppress root-lesion nematode, which costs the national grains industry $250 million annually.
"This natural form of suppression has been found to be much stronger in the surface soil and is more evident in long-term zero till, stubble retained soils, as opposed to soils which have been mechanically tilled and where stubbles have been burnt," she said.
"Given this knowledge, the next step will be to investigate how disease suppression can be encouraged at greater depths in the soil, where damage to plant roots occurs, and more broadly across cropping regions.
"We also know fertiliser is not the only source of N - free-living nitrogen-fixing organisms also have an important role to play - and the addition of fertiliser can, in some instances, decrease the release of N from soil organic matter and crop residues."
Scientists involved in the Soil Biology Initiative agree the program is making considerable progress in understanding the composition of the living fraction of soils which support crop production, and how growers can best manage soils to maximise nutrient capture and defend against crop disease.
"The current five-year phase of the Soil Biology Initiative, due to be completed in mid 2014, has involved 'world-beating' science," Assoc Prof Mele said.
"And even though it is very much pioneering work, on a global scale, we are now in a position where we can start to validate some of the findings and from there provide growers with recommendations on cultural management options and resource support."
Other new knowledge to emerge from the research has included:
- In the southern cropping region, analysis of cropping soils has indicated that farming systems are more resilient than previously thought;
- The positioning of microbial communities in the soil profile is now known. This could have implications in terms of fertiliser placement;
- Ammonia oxidising bacteria (AOB) have been found to be responsible for nitrification in the surface of Western Australian soils. In the subsurface soils, a completely different group, the ammonia oxidising Archaea (AOA), seem to dominate. This finding offers potential for positive intervention;
- The types of microbial communities vary regionally and therefore manipulation of biological functions (including use of inoculants) must occur at least on a regional level;
- Microbial communities and the products they form are distinctive in disease suppressive compared to disease sensitive soils.
To view an interview with Assoc Prof Pauline Mele about the Soil Biology Initiative, go to www.youtube.com/theGRDC.