Recent drought, coupled with increasing salinity on the north-west slopes of NSW have highlighted the potential of tropical grasses.

Livestock production systems in this area are typically based on cool season perennial grasses such as phalaris and fescue and annual crops such as oats.

However, these perennial grasses show poor persistence at lower elevations and many failed to survive recent drought conditions.

Trials at Manilla and Tamworth on both salinity recharge and discharge sites as part of the CRC Salinity’s national plant evaluation program, show a range of tropical grasses can outperform more traditional temperate grasses.

Katambora Rhodes grass stood out, producing up to 12,700 kilograms of dry matter per hectare over the 2004-05 summer when sown into a native pasture on a recharge site west of Manilla.

On the Tamworth saline site Katambora produced 3500 kg DM/ha.

While tropical grasses have been evaluated in northern NSW for over a decade, the work has largely focused on recharge environments says Greg Lodge from NSW Department of Primary Industries, Tamworth.

“The rainfall distribution of northern NSW, with 60 per cent of rain falling from November to March favours summer-based livestock production systems, so tropical grasses would be expected to perform well.

“Previous work has shown there is a range of tropical grasses wh are high producing and have the ability to provide green feed during summer and carryover dry feed during winter, and as more salt-affected areas begin to appear, there is an increasing need to find new pasture species which are both salt tolerant and productive.

“As a result, the ability of tropical grasses to use water looks increasingly important for both production and drying out the subsoil.

“An interesting feature of tropical grasses is their ability to rapidly respond to rainfall, producing large quantities of feed.

“At the recharge site on previously cropped land, tropical grasses in summer produced an average of 11 kg DM per millimetre of rain. This compared with temperate grass species sown in an adjacent area which produced just 3.7 kg.

“During the winter months, temperate grasses outperformed the tropical grasses, producing up to 6.5 kg DM/mm, with the tropical grasses producing 3.1 kg.

“When you look over the full season, the tropical grasses significantly outperformed the traditional cool season grasses, showing both their adaptability and potential in northern NSW.

“But while the potential for tropical grasses is there, and their popularity is increasing, little is known of their fertiliser and grazing requirements to maximise forage quality and persistence. Similarly, there is a need to look at their legume compatibility.

“Understanding the basic agronomy of these grasses, including how to get better establishment is essential for widespread adoption by producers.”

The trials evaluated a range of tropical grasses including Katambora Rhodes grass, Premier digit, Floren bluegrass, Swann bluegrass, Inverell purple pigeon grass and Bambatsi panic.

Contact Greg Lodge 02 6763 1176 greg.lodge@dpi.nsw.gov.au

This article is an extract from the CRC for Plant-based Management of Dryland Salinity’s Focus on Salt magazine, issue 34.

This story appears in Agriculture Today.