Less soil is eroded, and crops are more likely to withstand days of water logging following torrential rain, through higher humus levels advocated in organic farm systems. Experts say high humus levels will enhance farm resilience in all extreme climate fluctuations in the future.
“Organic farming systems do not result in erosion to the same degree as conventional because they stabilise soil structure by fostering organic matter and the release of exudates that aggregate into larger and more stable forms,” says soil technician and BFA spokesperson, Mr. Greg Paynter.
“Studies have shown soil resilience is built through the creation of stable humus. Farm systems that utilise this are more able to withstand climate extremes.”
“Increasing levels of humus is the cornerstone of organic soil management.”
Adam Willson, Director of Soil Systems Australia says soil rich in humus and organic compounds can retain moisture in the dry; and improve drainage in intense wet periods.
He says this is particularly important following the drought.
“Land tends to have been over-utilised - often graziers won’t de-stock during dry times - and the combination of bare soil and excess water can result in intense ecological and agricultural damage,” he says.
He says the numbers measuring this damage are staggering.
“Just 0.3mm of lost topsoil leads to 4.4 tonnes of soil per hectare moving downstream (roughly the weight of an African female elephant).”
Mr. Doug Haas, Chair of BFA and small intensive crop grower has seen the benefits.
“As a farmer who’s had almost 900mm of rain in the past month, I believe soil management and the accumulation of humus in a natural system has lead to a more resilient land,” he says.
Mr. Willson says grazing management in particular was critical because land subjected to heavy grazing or recent tilling eroded easily.
“Farming with as close as possible to 100% ground cover (vegetation) is one of the only things to stop this” he says.
An independent report to the Australian government states that soil erosion is responsible for increasing sediment loads in rivers and estuaries.
Areas worst affected include extensively cleared wheat and sheep zones in east and south-west Australia.
The report states nearly 19,000 tonnes of total phosphorus and 141,000 tonnes of total nitrogen are estimated to be transported downriver to the coast each year from agricultural activity.
Mr. Willson says high phosphorous runoff has led to the development of blue-green algae in water ways; and that the final settlement of sediment in oceans was responsible for arid marine ‘dead zones.’
Mr. Paynter says further examples of resilient organic systems in climate extremes also included:
A cropping trial (DAFF Farm Innovative Program, Dalby) where conventional wheat yielded 2.2 tons per hectare and the organic trial 3.3 tons per hectare, with better protein levels in the worst drought in 100 years;
On-farm dairy trials in Queensland where organic farm practises averaged 57.5 tons per hectare of silage (stock feed) compared to a district average of 17.5 tons per hectare in conventional farms utilising low quality irrigation water.