PASTURES Salt tolerant pasture production by Denys Slee

Melilotus has a history of helping to heal degraded soils.

AGRONOMIST PEDRO Evans believes that in Melilotus alba he has found a productive solution to the lack of income-earning potential from waterlogged and/or saline areas in medium-to high-rainfall country.

Mr Evans, of the Victorian Departmcnt of Natural Rcsources and Environment at Hamilton ,began working with this introduccd legumc pasture species in 1994. He investigated Melilotus bath as a companrion to the deep-rooted and salt-tolerant species, tall wheat grass, which is commonly used by farmers to counter rising waterables, and as a pasture species in its own right.

In both situations the amount of pasture produced on an annual basis on saline soils has matched the production from standard pasture species in the district not growing in salinised conditions.

Mr Evans says selections have been made from an introduced population of M. alba to find lines that have a low level of the anti-nutritional compound Coumarin, which naturally occurs in this plant species. "We are down to three lines with low Coumarin and will register the best of thesc," he said.

"In Russia, Argentina and Spain , Melilotus species are regarded as productive on saline land and they are also considered to improve degraded soil."

Trials

In a series of trials. start ing in 1998, accessions of M. alba were inoculated and sown at 20 kg/ha. Superphosphate at 250 kg/ha, containing molybdenum, copper and zinc, was applied, along with 150 kg/ha of muriate of potash.

Soils at the two sites had a pH (CaCI,) of 7.0 and 8.4 respectively in annual rainfall zones of 600 mm and 650 mm. At both, the performance of M. alha was compared with variolls 'controls' including the commonly grown Haifa white clover, Astred red clover and Palestine strawberry clover.

"A large quantity of dry matter was produced hetween Decemher and February at both sites,sllggesting the M. alba has the potential to fill the summer autumn feed gap," Mr Evans said.

On an annual basis both the combination of tall wheat grass and M. alba. and M. alba by itself, when grown on saline soils, produced similar amounts to those pastures in thc district not grown on sa line soils.

"These results suggest that production need not be reduced on waterlogged/salt -affected areas, but rather that the large amount of available water in these soils is an opportunity to obtain high yields of quality forage later in the growing season."

Mr Evans said regeneration of M. alba varied. In the second year following sowing, regeneration resulted in excellent autumn-winter production at both sites. In the third year it was10 times lower than the second year, which was " not too bad as it was still around 400 plants/m'''.

Mr Evans says there are other Melilotus species that have successfully been used as a pasture in other countries and are worth testing on saline sites.

He said if duty of care activities to determine its weed potential and effect on animals give acceptable results , then a cultivar of Melilotus may he available to growers in 2006.

Program 4 Contact: Mr Pedro Evans 035573 0963 email pedro.evans@nre.vic.gov.au