With the global supply of phosphorous tipped to be exhausted within 300 years, West Australian farmers are moderating their use of the vital resource that some fear will become a geopolitical warfare tool in years to come.

Key points:

  • Scientists estimate global phosphorous reserves will be exhausted in 300 years
  • Australia imports 80 per cent of its phosphorous supply
  • Farmers are using efficient methods to sustain and even recycle the essential mineral

Phosphorus is an essential plant nutrient, with no alternative.

The global food system is highly dependent on phosphorus fertilisers made from mined finite phosphate rock reserves. However, phosphate rock reserves are not equally distributed around the world.

China, Morocco, Western Sahara, the US and Russia, together, currently produce around 80 per cent of the planet’s phosphate rock supply.

At the same time, Australia is heavily reliant on imported phosphorous, which is estimated to make up 80 per cent of its supply.

So, dependency on imported product could severely impact food security as the global population continues to increase.

One of the main domestic sources, Christmas Island, is pencilled to wrap up its operations within 15 years.

However, West Australian farmers are making sure that — with efficient use of the natural supply that is left — the country has a sustainable future.

A hand, palm-up, reaches for a tiny, new plant emerging from the soil

The availability of phosphorous in the soil is essential for plant growth which, in turn, is essential for food security.(

ABC Rural: Cassandra Steeth

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Controlling who gets to eat

The potential for geopolitics to cause disruption could still arise if a single country controls most of the remaining resource that is essential for the provision of food.

William Brownlie is a scientist from the UK Centre for Ecology and Hydrology.

He said while it was unlikely, countries with the capacity to export phosphate rock or phosphorous fertiliser could implement export restrictions in the form of export taxes, quantitative restrictions or export bans.

“An example of the past was, in April 2008, when China introduced an export tax of 100 to 135 per cent on fertilisers, to ensure that fertilisers produced in China were used domestically,” Dr Brownlie said.

“This was driven by an increase in domestic fertiliser demand to match increased national agricultural production.”

No more wastage

An older man wearing a brown jumper and cap, standing among a crop of brassica, holding freshly picked produce in his hands

Market gardener and citrus orchardist Tom Mitchell says using phosphorous is all about achieving efficiencies.(

Supplied: Tom Mitchell

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For the past 21 years, Tom Mitchell has farmed a market garden and a citrus orchard northwest of Gingin in Western Australia.

Mr Mitchell said he was currently using a small amount of phosphorous in a pelletised chicken manure form, but that was not always the case.

“When we first started, we were using phosphorous in a granular form and used relatively heavy amounts,” Mr Mitchell said.

“I wasn’t from a horticultural background and was pretty green to it, [so] we basically followed the book and put out the recommendations.

“What we found —over time from soil testing — was we actually needed to put less on, and in fact, we were inducing problems by having too much, which was limiting the uptake of other nutrients.”

In terms of future crop growth, Mr Mitchell said it was all about achieving efficiencies.

“Hence the need to maximise the efficiencies of use now, to draw it out longer because there is going to be challenges ahead when we can no longer dig it out of the ground.”

Plants, science and survival

A grey-bearded man in a deep navy blue jumper, with arms crossed, standing in front of a barbed wire fence, sheep in distance

CSIRO pasture agronomist Dr Richard Simpson is researching how to improve phosphorous acquisition by root systems in pastures and arable crops.(

Supplied: CSIRO

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As the availability of phosphorous dries up, it is inevitable the mineral will increase in price, making it harder to sustain a growing population.

Richard Simpson is a plant and pasture agronomist with the CSIRO, Australia’s leading scientific body. He said that, while global supply was an issue, Australian farmers were winning the battle.

“It is not absolutely known, but the last audit I saw of the phosphorous reserves was that they would probably last 300 years at the current rate of usage,” Dr Simpson said.

“Overuse, for example, which causes pollution, just does not need to occur.”

Mr Simpson said there had been a long history of incremental improvements in pasture management and phosphorous use by conventional farmers across Australia.

“Leading farmers are adopting modern ways of testing soils, monitoring what they are doing, and trying to stay at optimum levels — which pays them back by having the highest production they can achieve per unit of land, at the lowest input cost.”

A conventional farmer point of view

Landscape shot of a ute on a farm paddock with a sunset in the background

On Tony White’s farm in Miling, there’s a mixture of cropping, hay and merino sheep, so the use of phosphorous is essential as there is too little phosphate in the region’s soil.(

Supplied: Tony White

)

Tony White’s family has farmed in Miling, Western Australia, for more than 100 years. Phosphorous has always been used on their property.

Over 5,160 hectares, Mr White runs an integrated system that includes mixed cropping, hay and merino sheep.

Mr White agreed that phosphorous was essential for crop survival.

“Phosphorous is pretty essential to getting the plant out of the ground.”

In Western Australia’s Wheatbelt, he said, the soils are “not really phosphate-available”, so it has to be added in.

Mr White said he was using soil tests and GPS farming systems to reduce overlap and wastage.

“I think there are a lot of positives looking forward. Innovation is going to help us,” he said.

 “Pricing is the biggest worry though.

“If we get priced out of phosphate … due to a world war or something, then we have got to come up with solutions, don’t we?”

Circular system in livestock

Man wearing a blue shirt, puffer vest, sunglasses and cream hat, in front of cattle yard, his crossed arms resting on metal gate

West Australian grass-fed cattle producer Warren Pensini uses minimal phosphorous, focusing instead on targeted inputs and retaining ground cover.(

ABC Rural: Tyne Logan

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Recycled phosphorous fertiliser could help shift reliance away from mined resources and could be a solution to supply chain risks.

It is a vision Warren Pensini has for his Blackwood Valley Beef business.

He runs grass-fed cattle just outside of Boyup Brook in Western Australia’s South West and said he had come a full circle on the application of phosphorous.

“Phosphorous is extremely important for livestock production, there is no doubt about that,” Mr Pensini said.

“It is an element that we look closely at.

Mr Pensini said recycling of nutrients was going to become important in the future.

“At some point we are going to have to move away from the mentality of just digging up resources and chucking it out there,” Mr Pensini said.

“Recycling nutrients, food waste, compost — we need to investigate making the system more circular, there is no doubt about that.”

Farmers moderate use of resource essential to life
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