BIOCHAR may sit well with environmentally conscious groups, but what's in it for farmers?

A soils research officer with NSW Industry and Investment (formerly NSW Department of Primary Industries), David Waters, is looking for the answers.

    AT A GLANCE
  • Who: David Waters
  • What: biochar
  • Where: Wagga Wagga, NSW
  • Why: what's in it for farmers?
  • Report: KIM WOODS

David has started southeast Australia's first biochar trial under broadacre crops and pastures.

The trial, at two sites, Holbrook and Wagga Wagga, will involve canola, wheat and improved pasture.

David said biochar - the carbon-rich solid product produced by heating biomass, such as plant matter, animal or human waste, in an oxygen-limited environment - was often misunderstood and confused with coal or peat.

The biomass is treated in a pyrolysis (heat) plant, similar to an oven where the temperature and atmosphere is controlled.

There are two byproducts from the process - biofuel or gas (hydrogen, carbon monoxide) and biochar.

Applied to the soil like fertiliser, biochar has the potential to improve water-holding and cation exchange capacity, soil structure and plant biomass.

David said the biochar was chemically different from coal and peat.

"Coal is compounded plant matter formed over eons of time; in biochar, the heating process changes the chemical structure to an aromatic form of carbon," he said. "This means it is stable in the soil.

"Biochar has potential for agronomic benefit as a soil conditioner, both directly and indirectly.

"It does seem to present ... potential in terms of sequestering a stable form of carbon.

"But we are very much in the infancy of the whole thing."

David said different types of biomass combined with particular temperatures gave a biochar with differing characteristics.

In southern NSW, a three-year biochar research project began at the EH Graham Centre, Wagga Wagga, last year.

Two cropping and pasture trial sites will be established at Holbrook and Wagga Wagga next year.

At Wagga Wagga, the biochar will be incorporated over summer at 0-10cm depth at various rates.

It will be tested under canola followed by wheat.

David said application rates would depend on glasshouse nutrient leaching trials now underway.

The biochar will be compared with the inorganic fertiliser DAP at 100kg/ha and a control plot at zero fertiliser.

As the first biochar trial in southern NSW, it will complement research done on the NSW North Coast over the past four years.

Measurements will be taken on plant biomass, yields, nutrients, water retention and the aggregate stability of soils.

David said the biochar in the trial was produced from green waste and poultry manure.

It is made on the NSW Central Coast by a small pyrolysis plant which supplies biochar to research institutions.

David said the biochar made from poultry manure could be high in phosphorus, potassium and nitrogen.

"Biochar is not the panacea," he said.

"It can have a negative impact on certain soils.

"Biochar should be considered as part of a suite of mitigation tools."

There is no commercial biochar industry in Australia but several large-scale plants are under construction, he said.

A West Australian plant would be fuelled by prunings from mallee eucalypts.

"I am trying to encourage larger councils with green-waste depots to consider biochar plants," David said.

"But a biochar industry will not happen if it is not useful enough agronomically.

"I feel the biochar will do well and improve the nutrient efficiency of soils, particularly for sulphur."