Salinity tested by six tonne 'flower pots'

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." "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.

Item provided courtesy of CSIRO