August 13,  2001
Ref 2001/182

Two six tonne 'flower pots' at Wagga Wagga are being used by CSIRO researchers working towards a solution for the problem of dryland salinity. The huge pots, or lysimeters, are used to measure the consumption of water by crops. They are an essential part of a project conducted by CSIRO's Dr Chris Smith, Dr Warren Bond and Mr Frank Dunn who are working in close association with farmers.

"Each pot weighs more than six tonnes, but we weigh them to an accuracy of less than 30 grams," says CSIRO Land and Water's Chris Smith. "We can measure very accurately the amount of water which is used by the crops, and the amount of water which 'leaks' past the root zone," he says.

The spreading threat of dryland salinity is linked to 'leakage' of water, according to Dr Smith. Today's shallow-rooted cropping systems use less water than the native vegetation which they have replaced. This allows more water to leak past the roots to the groundwater. The groundwater level then rises, bringing with it ancient deposits of salt, the cause of dryland salinity.

"Australian farmers are going to have to adopt different cropping systems which use more water," says Dr Smith. "This will contribute to halting the spread of salinity. "Repairing the damage where it has been done will be very difficult indeed," he says. "The best investment for Australia's land managers will be in a newly-designed agricultural landscape which will prevent any further degradation."

Dr Smith says that one crop which has been shown to be effective is lucerne.

"Our lysimeters have demonstrated that a system of lucerne grown in rotation with other crops has a measurable effect in combating salinity," he says. "Other options include developing crop varieties that use more water during the growing season, and introducing perennial 'companion crops' into the farming system."

Dr Smith says that the problem of rising groundwater and the consequent salinisation of agricultural land over the last century could be resolved by re-introducing trees. However the amount of land needed would have a damaging effect on farm income, especially in areas where the rainfall is too low for commercial farm forestry.

"Clearly we are going to have to develop the right mix of agricultural crops, farm forestry, and
significant areas of native vegetation," he says. "We are looking for cropping solutions that leak less water to the groundwater while at the same time maintain productivity and profitability."

The lysimeters are playing a key role in the measurement program, being the only direct way to
measure plant water use.

"We've measured water balance in canola, wheat and triticale crops, lucerne and native vegetation at sites in the Wagga Wagga district," he says. "These measurements allow a direct comparison of the pattern of water use with that of native forest."

Dr Smith says that local farmers in the district have given invaluable support to the project, as have
Charles Sturt University, NSW State Forests, Land and Water Australia, and the Grains Research
and Research Development Corporation.

More information, pics, from:
Chris Smith, CSIRO Land and Water, 02-6246 5960, 0438 124 564
Marg Bryant, CSIRO Land and Water, 08-9333 6215

Contacts:
 
Dr Christopher Smith
Project Leader
CSIRO Land and Water
GPO Box 1666
Canberra ACT 2601
Phone: +61 2 6246 5960
Fax: +61 2 6246 5965
Email: CJ.Smith@cbr.clw.csiro.au 

Mr Nick Goldie
Journalist
CSIRO National Awareness
PO Box 225
Dickson ACT 2602
Phone: +61 2 6276 6478
Fax: +61 2 6276 6821
Mobile: +61 0417 299 586
Email: Nick.Goldie@nap.csiro.au

CSIRO news release
N3717