Checking lucerne model for medium-low rainfall areas by Eammon Conaghan
LUCERNE HAS a proven track record as forage and in cropping rotations in WA's higher-rainfall southern and coastal agricultural regions. However, its winning ways elsewhere are less well-known in medium- to low-rainfall areas.
WA Department of Agriculture 's Roy Latta and Keith Deveni sh studied the performances of lucerne and annual legume pastures for water use, forage production and subsequent crop yield in phase pasture-crop rotations.
Results were recorded from two research sites in the central wheatbelt and nine commercial sites in the central and northern wheatbelt, within the 300-450 mm rainfall zone, with a range of soil types and soil acidity levels.
Slow establishment, sandy acidic soils and extended dry summers reduced the productive stand life of the lucerne to 1- 2 years of a three-year pasture, one-year crop rotation.
Dry summers challenge lucerne, may decrease water for following crop
More than 30 plants per square metre were established at all sites, however plant numbers declined to less than 10 over an extended dry summer. Grazing had less impact on plant numbers than dry summers.
In the project's establishment phase, lucerne biomass was 60 per cent of annual pasture, but was 40 per cent greater than annual pasture in autumn-winter, following autumn rain.
Lucerne's high water-use meant that, after dry summers, crops following the lucerne phase could have reduced yields due to soil water deficits.
The research demonstrated that lucerne could be successfully established in the central and northern wheatbelt. However, establishment and management strategies must be employed to help minimise the production losses in response to low annual and summer rainfall.
Strategies to deal with dry conditions
Recommended strategies include sowing lucerne at 2 kg/ha in alternate rows with a companion field crop to help account for low production in the establishment phase and removing lucerne in the spring prior to returning to crop, to allow for available soil water and nitrogen to accumulate.
Program 4 Contact: Mr Roy Latta 08 9821 3333