A recent CSIRO publication on soil health and soil biology summarises what biological farmers have known for a long time: Soil organic matter has a huge impact on soil properties.
Dr Graham Stirling’s guide, “Soil Health, Soil Biology, Soilborne Diseases and Sustainable Agriculture”, explains that organic matter can, improve soil structure and water-holding capacity, help control nutrient cycling and nourish organisms that compete with pests and pathogens.
Stirling and his co-authors also address the challenge of how to build and hold onto the organic materials that are constantly decomposing.
In Australia’s climatic extremes of high temperatures, long dry spells and flooding rains, it can be difficult for farmers to keep organic materials in the soil, doing their job.
Cairns sugar cane farmer, Mark Savina, says he’s been putting 15t/ha of biomass on to the ground every year for the last 36 years.
“But this has done nothing for our organic carbon levels,” Mr Savina said.
He is currently working with Bob Shaffer, Hawaii-based agronomist and a strong advocate of “growing your organic matter”, to prepare a cocktail of cover crops for an on-farm demonstration workshop associated with the National Biological Farming Conference.
Mr Savina hopes that along with breaking up compaction, cover crops might assist with improving the quality of water flowing into the Great Barrier Reef lagoon.
Mackay cane farmer and Nuffield scholar, Simon Mattsson, has been seeing some positive results from a mix of legumes, daikon radish and sunflowers in his cane crop. He has also reduced tillage and herbicide use and is cautiously optimistic about the benefits.
“The plant cane under the sunflowers looks better than the rest of the field,” Mr Mattsson said.
“It's quite interesting because in the rest of the field I am using tillage to control weeds and where the sunflowers are, I am just letting nature take its course - no tillage, no herbicide,” he said.
The conference is convened by Wet Tropics Soilcare, Terrain NRM and SoilCare Inc with funding provided by the Australian Government and several other valued sponsors.
