Lucerne on mallee soils: weed control assistant

WITH THE frequency of cropping set to increase in the mallee areas of NSW, Victoria and SA, CSIRO Land and Water scientist David Roget sees an increasing role for lucerne plantings in the region.

"As the intensity of cropping increases, farmers will run into problems with grass weeds and herbicide resistance, and we see a role for lucerne in weed control,"

Mr Roget said. "There is a range of selective and non-selective herbicide options for control of annual weeds in lucerne, once established.

"More work needs to be done on this but perhaps farmers who are intensively cropping would need to consider a stand of lucerne lasting two years in every 10. But it is important to consider the economic contribution lucerne can make to the whole farming system, not just the value of a two- or three-year lucerne phase."

Nitrogen recoverer too

Mr Roget said lucerne had the potential to recover significant soil nitrogen reserves found in mallee soils. The nitrogen had been leached deep into soil profiles, generally following multiple summer rainfall events - losses of nitrogen being higher following long fallows.

Nitrogen reserves of 220- 720 kg/ha to 6 metres had been found in Victorian mallee paddocks, and of 257- 1,153 kg/ha to 6 metres in SA mallee soils.

"Shallow-rooted cereals, not helped by the presence of various toxicities in many mallee soils, have been unable to utilise this nitrogen," Mr Roget said.

Program 4 Contact: Mr David Roget 08 8303 8528