An exciting new pasture plant for southern Australia’s saltland is being hailed as an important agricultural discovery.
The new annual pasture legume messina (Melilotus siculus) is an outstanding option for saline waterlogged environments where current commercial legumes fail to survive.
South Australian Research and Development Institute Pasture Research Officer Amanda Bonython says messina’s tolerance to the combined stresses of salt and waterlogging are unmatched and greatly surpasses that of all other legumes.
In 2000, 5.7 million hectares of Australia’s agricultural land was affected by dryland salinity, with 270,000 ha of the Upper South-East of South Australia affected. Areas affected by dryland salinity tend to also experience waterlogging and inundation.
“The combined effects of both salinity and waterlogging render salt-affected areas unsuitable for cropping and they are mostly used for livestock production,” says Ms Bonython.
“Saltland pastures in southern Australia are generally based on native saltbush (Atriplex) species in low rainfall areas and salt-tolerant grasses (tall wheat grass and puccinellia) in high rainfall areas. Current pasture legumes are sensitive to salinity and as a consequence saltland lacks a legume base.
“Without a legume saltland systems are nitrogen deficient. An adapted legume is required to fix atmospheric nitrogen and increase overall pasture and livestock productivity.”
This makes messina an important discovery to Australian agriculture. A messina pasture in the Upper South-East of SA produced 5.9 tonnes/ha to August 2010, compared to a puccinellia pasture with 1.8 tonnes/ha. An added advantage is that unlike other Melilotus species, messina has negligible levels of coumarins. Coumarins are chemical compounds that can cause tainting of milk, meat and grain, as well as occasional livestock health issues.
Furthermore, messina has been classified as posing a negligible weed risk to the environment.
The development of messina has been hampered by nodulation failure in regenerating stands. Research in the Upper South-East of SA and in WA has shown that 70% of second year messina plants fail to nodulate. Poor nodulation has occurred when messina is inoculated with the current Group AM ‘medic’ strain of rhizobia.
An extensive field and glasshouse program, funded by the Future Farm Industries CRC and undertaken by SARDI and Department of Agriculture and Food WA (DAFWA) scientists, has evaluated over 100 new strains of rhizobia in the field. The strains have been isolated from plants and soils sourced from saline environments and have been evaluated for nodulation effectiveness with messina and persistence over summer. Nine elite strains have been identified as having greater persistence than the Group AM ‘medic’ strain and these strains are currently in their final evaluation phase.
Running parallel to the rhizobia evaluation is a comprehensive evaluation of the messina plant germplasm. Twenty-one accessions of messina have been sown in multi-site field trials in the Upper South-East of SA and in WA. Measurements to be taken include seasonal dry matter yield, seed yield, regeneration and growth habit. Messina’s tolerance to grazing will also be evaluated.
A successful messina seed and rhizobia collection mission to Spain was undertaken in 2009, with additional support from the AW Howard Trust Inc. Messina grows naturally in saline and waterlogged environments in Spain and the collection increased the diversity and robustness of messina seed and strains of rhizobia for evaluation.
Messina is an outstanding pasture option for areas affected by dryland salinity. Messina and accompanying rhizobia are expected to be commercially available by 2014.
This research is funded by the Future Farm Industries CRC and conducted by SARDI and DAFWA.