A scientific trial using composts and soil conditioners on a central Queensland property has shown how chemical run-off to the Great Barrier Reef can be dramatically reduced.
Queensland organic waste recycler NuGrow and leading soil scientist Dennis Baker conducted the trial to see whether this could reduce synthetic fertiliser loads.
Mr Baker, the former head of the Queensland government’s Soil Analytical Laboratory and a 47-year industry veteran, described the results as outstanding.
“I am a chemist by profession and have advocated long and hard that organically based composts can dramatically reduce chemical run-off to the reef while maintaining and even increasing agricultural yield,” he said.
The trial was run on the Olive family’s Raglan Station, 60 kilometres south of Rockhampton. The property adjoins the Fitzroy delta, an environmental hotspot and major catchment for the Great Barrier Reef.
Third generation farmer Ryan Olive said the initial trial results were a surprise, with pastures using organic soil conditioners returning three times the volume of growth of untreated pastures.
“We sowed numerous controlled plots with lucerne at the same time, with exactly the same soil profiles and exactly the same watering conditions,” he said.
“Some pastures had nothing added, while others had various ratios of organic soil conditioners.
“In short, the weight and yield from the pastures using soil conditioners was beyond what I was expecting over a six-week period,” he said.
“And at less than one-tenth of the price of synthetic fertiliser, you have to seriously look at this.
Mr Baker’s analysis revealed that apart from significant increases in volume, the pasture using compost retained moisture better, had increased digestibility and contained more protein than other pastures.
Samples of pasture from 1 square metre on the controlled plot and 1sq.m on the 10 tonnes/hectare compost plot was harvested to determine the difference in density.
The controlled plot returned a weight of 576 grams/sq.m while the 30t/ha plot returned a weight of 1704g/sq.m.
“Here we have proof that soil conditioners work,” Mr Baker said. “This is a potential game-changer for the reef and if adopted more broadly will reduce damaging run-off in sensitive catchments.
“Over a three-year period, with a tailored regime that meets the soil profile of the property, I can see some farmers reducing their need for synthetic fertilisers by over 70 per cent,” he said.
Details of the first trial were released at an open field day at Raglan Station in early December.
