Another potential weed that scientists plan to unleash on unsuspecting farmers. Add this to all those other ‘wonder species’ that are now a plague on Australian landscapes. Lets hope it doesn’t add a new wasteland.
Written by Narelle Towie
SCIENTISTS have unearthed a plant they say can transform hectares of WA’s arid wasteland into fertile farmland.
Large areas of the state are plagued by sandy, acidic soils that struggle to support agricultural plant life.
Our local Kimberley weeds such as Leucaena, Siratro, Merremia, Stylosanthes, are just a few that have invaded our landscapes in areas and conditions quite the opposite of the where and what the real intention of what their ‘pasture improvement’ was supposed to bring. The cost of eradication becomes enormous, such as the Neem trees, Mimosa, Noogoora Burr, Kapok, and other burred grasses.
Farmers began planting a South African legume shrub, called lebeckia, last year as part of a large-scale trial across 15ha of the Great Southern, east of Narrogin.
Legume plants house bacteria in nodules on their roots that convert air into fertiliser.
Called rhizobia, the bacteria use the enzyme nitrogenase to break the chemical bonds that bind atmospheric nitrogen atoms.
Murdoch University agriculturalist Professor John Howieson and his team at the Centre for Rhizobium Studies discovered lebeckia in a decade-long global search for legume plants capable of surviving through WA’s harsh, rainless summers and arid soils.
“Our discovery is significant,” Prof Howieson says.
This species has now been let loose, at least now we will know where the blame lies if/when this spreads where not intended, like another legume, Stylo.
“I sent teams all around the world looking for new legumes that might work in our changing climate and one team came back from South Africa and said ‘this is where we should focus our research’,” he says.
“We went back four times and collected lebeckia and all its nodules and bacteria and in doing that work we found a species of rhizobia that no one had ever worked on before.”
Overseas plant proved most suitable
Prof Howieson says plant breeders historically worked on adapting common legume plants, such as peas or white clover, to Australia’s harsh climate and poor soils, but that these plants don’t grow well here.
His team took a different approach.
They scoured the planet for non-toxic legumes that were growing well in rangelands similar to WA and then imported them to Australia.
The plants were “domesticated” and eventually selected to tolerate grazing by sheep.
The plants also produced shatter-proof seed pods important for machine harvesting.
Prof Howieson says lebeckia is special because it remains green during summer, giving farmers extra high-quality feed during hot, lean months.
“Early grazing studies by Samantha Lubcke at Murdoch University indicate that lebeckia can close the summer/autumn feed gap for merino sheep in arid environments,” he says.
“Apart from the woody tree tagasaste, no other perennial legume can tolerate these particularly harsh soil and environmental conditions and other legumes like lucerne and tedera does not grow in these soils.”
In 2010 the first agronomic trials were planted in WA’s northern and southern wheatbelts.
Prof Howieson says the smaller trials revealed the shrub can improve carbon content, phosphorus, nitrogen and potassium in poor soils.