CSIRO's Paul Hutchinson (foreground) and NSW DPI's Tony Bernardi install a new drainage meter at Baldry, one of eight key salinity research sites in NSW.

Specially developed new drainage meters will supplement what little data exists to explain how water and salt movement change in a catchment in response to large scale tree planting.

In mid-March, three of these meters were installed at Baldry, a 260 hectare sub-catchment of the Little River in the Upper Macquarie Valley, west of Yeoval - one of eight high priority dryland salinity 'key sites' in NSW being studied in a long-term project.

Other instruments on this site are measuring how the growth of 60 hectares of native hardwood plantation trees affect local and catchment water and salt movement as the plantation grows.

This will be compared to the response under cropping and pastures.

Drainage meters are installed below the root zone (the area ofthe soil where plant roots extract water); here they detect when water moves past the root zone and calculate the amount of water that can potentially recharge into the water table or flow laterally into streams.

The meters are effective in different seasons and for varying rainfall patterns.

'We have an idea what happens when there are no trees or when trees are well established such as in a remnant native forest - but we don’t know what happens during the transitional phase,' said Queanbeyan based DPI research hydrologist, Tony Bernardi.

'This will let us determine changes in water balance in the transitional phase as trees establish.

'Work at Baldry started in 2003 and has been carried out during a dry period.

'We are waiting to for good rainfall to trigger measurable water moving past the root zone for the drainage meter to measure.

'Data gathered at Baldry will compare simulation model out-put to reality, testing the accuracy of what the model is telling us.'

Mr Bernardi said the 'key sites' project will improve models and decision tools being increasingly used by catchment management authorities and extension staff to make land use recommendations.

'The meters will also let us analyse what’s in the water going through the root zone, for example, nutrients like lost nitrogen, and/or salt.'

Previous research has made it clear that different solutions are needed in different areas and that even an apparently simple option such as planting trees is only beneficial in the right location.

In September 2001 NSW State Forests established 60ha of Eucalyptus camaldulensis and Corymbia maculata on the western side of the creek line at Baldry.

The eastern side of the creek has continued under cropping and is now going into pasture.

Paul Hutchinson of CSIRO’s Division of Land and Water at Griffith developed the drainage meters with GRDC support.

The key sites project is a joint effort between the NSW Departments of Primary Industries, Natural Resources, the CRC for Plant Based Management of Dryland Salinity and the universities of Sydney, NSW and UTS.

Contact: Tony Bernardi, Queanbeyan, (02) 6297 1861, 0428 166 735 or tony.bernardi@dpi.nsw.gov.au

- RON AGGS

This story appears in Agriculture Today.