Why soil health is like good gut health when it comes to growing bananas

Banana growers in Carnarvon are hoping to apply the theory of good gut health to their soil in a bid to make healthier fruit.  

In what is believed to be an industry first, Carnarvon's Sweeter Banana Co-operative has launched a three-year trial which will compare sub-tropical bananas grown using synthetic fertiliser to those grown with a biomineral fertiliser.

Sweeter Banana Co-operative business manager Doriana Mangili said good soil health was akin to good gut health.

"The addition of fertilisers is a bit like adding a soft drink or refined sugar to your diet — it'll give you energy and it'll get you going but in the long term it's not great for your gut health," she said.

She said soils were the same.

The bananas, grown side-by-side, will undergo leaf, soil and shelf-life testing to assess the difference between conventional fertiliser and the biomineral product. 

Worst case is the same, but cheaper: agronomist

Agronomist Scott Brain said he had been working to improve nutrient use efficiency with growers in the Gascoyne since 2016.

Mr Brain said the biomineral fertiliser solution was significantly more cost-effective and would improve yield, quality and plant resilience.

"Research has shown that products such as urea only result in 30 per cent up take, so 70 per cent loss is often accepted," Mr Brain said.

Mr Brain said his product was based on conventional fertilisers with biological and mineral components introduced. 

"All we're doing is using a conventional fertiliser that has a specific coating on it, so the nitrogen, for example, is being meted out the rate that plants can take it up in, rather than being released too quickly," he said.

"When that occurs, you actually increase the nutrient uptake or availability of the nitrogen for the plants." 

Mr Brain said banana growers would use 40 kilograms of biomineral fertiliser per hectare, compared with 440kg per hectare using conventional fertiliser. 

"When I started this work people just said 'why would you bother because fertilisers are cheap, so you just put more on'," he said.

"But obviously with the changes in the economic climate, there's a lot more interest in trying to understand and implement these systems now."  

Mr Brain said he had not yet found a downside to the system having seen results in other trials of tomatoes and sweet corn.

"At worst, the same yield is achieved but in general we end up with a higher quality product," Mr Brain said.

Not everyone is convinced

Mr Brain said he had encountered his fair share of naysayers during his six years of work with the system — including himself when he was first approached to independently review the science. 

He said the science was "hiding in plain sight" and had been overlooked.

"At first I dismissed it ... then I went back and had a look at it and I could see the merit in the work," he said. 

Ms Mangili said she was confident the larger-scale trial was low-risk for growers having seen success in a smaller proof of concept trial. 

"Getting horticulturalists, growers to change what they've done is always a tricky process," she said.

"If we can prove that this works successfully in bananas ... perhaps the future of Carnarvon could be growing things in a more regenerative way with healthier soils and that can be our point of difference."

Premium price potential

Regenerative agriculture is not a new concept and has been trialled successfully in a range of livestock and broadacre operations for decades.

But Ms Mangili said the uptake was not common in horticulture

She said it was also hoped consumers would be willing to pay a premium for the fruit if nutritional benefits could be proven.

"We're hoping to see better nutrition, better range of nutrients, higher levels, and better shelf life as well," Ms Mangili said.

"And I think if consumers understand that ... they probably will be willing to pay a little bit more for something that's going to be better for them.

The three-year trial has been part-funded by State Natural Resource Management and the University of Western Australia, as well as the Sweeter Banana Co-operative.