Does money grow on trees? by Guy Cotsell and Cathy Nicoll

Kieran Forrest explaining grazing management among oil mallees on a site at Narrogin.

A billion trees pumping out water that causes soil salinity and waterlogging in WA's wheatbelt, with a bonus: a renewable cash crop from the trees.

This is the vision of the Oil Mallee Association, a West Australian umbrella group seeking to develop an industry based on fast-maturing mallee species and profitable land-care.

According to Association administrator Ric Collins, 350 farmers have planted more than nine million trees in the last five years.

The mallee species they used were chosen by the Department of Conservation and Land Management (CALM) for their high oil content, coppicing ability and suitability to the range of soil and climatic conditions found in the WA wheatbelt.

Revegetation with local species

Four out of five species grown by Esperance grains-sheep farmer Greg Bannon are found locally. The opportunity to replace some of the native vegetation was one factor in his decision to plant oil mallee.

Mr Bannon buys seedlings from the local CALM seed orchards. At 25 cents for each seedling, amounting to a cost of about $350/ha, he says the cost of establishment is not prohibitive.

Additional establishment costs include weed control and ripping prior to planting, the labour cost of planting by hand, and follow-up spraying for weed and insect control. There is no need for pruning or thinning. Tip removal and ringbarking by parrots are actually beneficial to the plants.

Fitting in with cropping, grazing

Profitable crops can be grown between hedges of two or three rows of trees. The target of revegetating 20 per cent of a catchment is achieved by planting extra blocks of trees in difficult-to-access corners and wet patches. Wider belts of trees are planted at breaks in slope where waterlogging can be a problem. The trees don't seem to compete with adjacent crops because they are so deep-rooted.

"An added advantage is that once the trees are established we can let sheep in without the need to fence off each tree belt," says Mr Bannon. "The leaves aren't palatable to sheep because of the high oil content."

Quick turnaround

Oil mallees are ready to harvest about four years after being planted. Subsequent crops are provided by regrowth — every two to three years in higher-rainfall areas. Yields range from 100 kg of oil per hectare to 200 kg/ha.

"Even at the lower yields we get here in Esperance, the potential is there for a good return on our investment once a commercially viable harvesting and distillation system gets going," says Mr Bannon.

"Any return will be welcome, as it will offset the establishment costs. My main reason for planting was for land care. In this rainfall zone (less than 500 mm/year) you can't grow blue gums, so your options for waterlogging and salinity control are a bit limited."

Trial plantings completed

Mr Collins says the past year has seen completion of trial plantings, and any grower in the wheatbelt could now participate in the program. The goal is an additional 30 million trees in the ground each year.

Contact: Ric Collins, Oil Mallee Association 08 9478 0330 Greg Bannon 08 9079 2085

What about...

Ground Cover posed a few probing questions about the current market for oil mallees. Here's the response.

Harvesting. There is no effective commercial harvesting machinery on the market so the Oil Mallee Association Ltd is building its own harvester for cutting, chipping and materials handling of eucalypts. It will be ready for field trials soon after Christmas 1998. The harvester is being designed to harvest 50,000 trees per day, of varying size and shape. Big plantations are needed to avoid down-time.

Processing. Working jointly with Curtin University, the Association commissioned a continuous-flow distillation unit last May. Early results are encouraging, but there is still need for more development to reduce production costs. The Association is also working on another distilling project.

Markets. The traditional pharmaceuticals market for eucalyptus oil is limited and well supplied and seems unlikely to expand. A promising — and potentially huge — market is in solvents, where 'natural' products are sought to replace trichloroethane, now discontinued under international conventions to control ozone depletion.

The local mining industry has trialed the product as a workshop solvent and degreaser, and has indicated that it will accept mallee oil commercially once guaranteed a reliable supply of sufficient volume, and provided the price is right. The Association is developing new product outlets.