Student Solves Soil Mystery
When a group of South Australian farmers took action to combat dryland salinity, they
were puzzled to find that their soils were still degrading and their pastures suffering.
The farmers, members of the Keilira Farm Management Group (KFMG) in the state’s
upper south-east, called the Future Farm Industries Cooperative Research Centre in to
investigate.
PhD student Melissa Fraser, of the CRC, found that the ailing pasture was largely
confined to clay-rich soils common to the area, about 242 km south-east of Adelaide.
“There are two distinct soil types throughout the Keilira district—a deep, clay-rich soil
and a shallow sandy soil overlying limestone,” she said.
The combined effects of climate change and artificial drainage had reduced salinity but
left high levels of positively-charged sodium ions in the soil, leading to another land
degradation problem, called sodicity.
“When these soils become wet, the sodium causes dispersion,” she said. “Fine clay
particles move down through the soil, blocking the pores essential for holding the air and
water that is vital for plant growth.” Sodicity affects more than 60 per cent of Australia’s
cropping land. The Keilira farms had soil types predisposed to it.
Ms Fraser worked with KFMG as part of her PhD project, hosting field walks and
attending field daysin conjunction with the farming group. The aim was to inform local
land managers, agronomists and consultants of the variability in soil types and the
interaction of salinity and sodicity. The work was supported by KFMG and the South
East Natural Resource Management board.
The farmers are now treating their soil with gypsum, seen widely as one of the best
defences against sodicity.
Ms Fraser is one of eight early career scientists invited to present their research results at
the Cooperative Research Centres Association’s Pathfinders Conference at the National
Convention Centre in Canberra this week. The CRCA represents Australia’s 50 CRCs
operating under a federal government program to drive public/private sector research.
Information:
Greg Lawrence Ph 0429101 675 E: greg.lawrence@futurefarmcrc.com.au
CRCA Media Ph 0419 250 815; Email crcamedia@gmail.com
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