The research, led by Dr Greg Doran from Charles Sturt University’s (CSU) School of Agricultural and Wine Sciences, in collaboration with Dr Mark Stevens, a principal research scientist at the NSW Department of Primary Industries (DPI), is investigating the efficiency of fumigation using what’s known as thermo-siphoning systems for grain silos.

“There’s a zero-tolerance for live pests in grain off-farm and the most common control method is fumigating using phosphine gas,” Dr Doran said.

“Commonly, aluminium phosphide tablets are incorporated into the grain as the silo is being filled, tablets can be hung in the headspace of silos, or a fumigation box and circulation fan can be used to circulate the phosphine gas.

“Thermo-siphoning phosphine in silos is a more recent development and involve the use of solar radiation to warm air in an external pipe, causing it to rise to the top of the silo, carrying phosphine from a fumigation box at the base of the silo. “The greater density of phosphine relative to air causes the phosphine to sink to the bottom of the grain chamber, fumigating the grain in the process. “We are examining how this fumigation technology performs under different climate conditions.”

For effective phosphine fumigation, the Grains Research and Development Corporation (GRDC) recommends a minimum of 300 parts per million (ppm) gas concentration for seven days, or 200ppm for 10 days.

Using a silo at CSU in Wagga fitted with sensors, the researchers will measure the temperature, humidity, dispersal and concentration of the phosphine gas in a number of experiments over the next year. “We aim to test the parameters of this fumigation technology to provide information to the silo manufacturers and the grain growers who may use the technology,” Dr Doran said.

The research is supported by an innovation connections grant as part of the Australian Government's Entrepreneurs' Programme, in partnership with HE Silos at Forbes.