Researchers are trialling the use of a new material obtained from human waste to improve soil fertility and increase crop productivity in grain-growing regions.
Biosolids, which are collected from dry sewage, can be used as a possible solution to the significant subsoil issues hampering the Victorian grain industry.
In addition to boosting grain production, the project has the potential to save farmers money because biosolids are available for free from state water supplies.
Federation University's Nimesha Fernando, a research fellow contributing to the project, said Australia had large amounts of clay in the soil.
"Subsoil constraints are very prominent in Australia — more than 80 per cent of grain growing soils has some sort of subsoil constraint," she said.
"When we go below 30-40 centimetres from the surface we will find very hard clay, the hard pan.
"This hard pan restricts the crop to grow up to their potential yield."
Full circle
Federation University professor Singarayer Florentine, an expert in restoration ecology, said Australian soil created hurdles for crop growers.
"The clay soil plays a critical role when the crop reaches maturity, and that's the time it will require additional nutrients and water," he said.
"Current subsoil is not providing those two major elements, so technically we can say they are physical barriers for the crops to grow."
Dr Fernando said introducing biosolids from state sewage could be a financially viable solution to the problem,
"It's a very good organic matter and rich with nutrients — all the minerals that are required for the crop growth," she said.
"State-of-the-art technology is used to produce biosolids in water amelioration centres in Australia, so they produce a very clean product."
Farmers are already improving soil by using fertilisers, such as lucerne pellets or chicken manure, but currently available products are expensive.
"Obviously those ameliorates are quiet expensive, farmers can't always afford to use those things," Dr Florentine said.
Strong growth
Dr Florentine said reaching below the surface to fertilise and loosen the hard clay subsoil was the key to success.
"The biosolids application has been happening for a long time, but they have been applying the biosolids only on the surface," he said.
"We have placed a freely available nutrient rich biosolid onto the surface of the clay to ameliorate that particular zone.
"We are placing it at the critical zone to capitalise further.
"In the field we need to place that biosolid at 10 tonnes per hectare, as defined and approved by the [Environmental Protection Agency]."
The deep placement of biosolids is a new concept established in this research.
"In the two trails we are using high and medium rainfall zones, we are using wheat in the Balliang and the Ballarat area," Dr Florentine said.
"We harvested two months ago and we are getting a 55-65 per cent [increase] in the crop yield when compared to the untreated soil.
"So it clearly shows production, the crop yield has significantly improved."
Long-term investment
The Grain Research Development Corporation-funded research project is aiming to build on these results and extend the trial period to understand the longer-term affects of fertilising subsoil.
"We're hoping to continue on for at least another two years so that we can see the temporal changes, as well as how different crops respond with the treatment," Dr Florentine said.
"We're not only looking at the yield, we're also looking the soil's physical and chemical changes.
"The physical aspect is whether the soil has become looser, whether the soil can hold moisture, what is the nutrient content?"
So far, Dr Florentine said, the results were promising.
"We have excavated to demonstrate [the results], and we could clearly see the crops have nicely sent the roots towards where we placed the biosolids, which is a good sign," he said.
"We want to provide a conducive condition for the crops to capitalise this application and grow and produce a better yield."
