Reducing demand for phosphate fertilisers

Ninety per cent of phosphorus use is for food production. Yet, according to Dana Cordell, of Sydney’s Institute for Sustainable Futures and the Department of Water and Environmental Studies, Linköping University, Sweden, while the world’s population requires only three million tonnes of phosphorus per year, almost 15 million tonnes of phosphorus are mined for fertiliser. Significant losses occur all along the chain from mine to plate, much of it in the growing, harvesting and transporting of food.

For farmers, the obvious start is improving agricultural efficiency, but they should also consider the efficiency of the food chain, according to Gerry Gillespie of the NSW Department of the Environment and Zero Waste Australia. “Under a reverse program to return organic material to agriculture, Zero Waste Australia has initiated the Plate to Paddock program, which will ensure that only the highest quality, source separated organic waste is made into compost for use on our farms,” he said.

While Zero Waste’s discussion paper, From Paddock to Plate: From Plate to Paddock is aimed at the consumer, its conclusions are valid for farmers as well as city folk:

“Peak phosphorus is telling us that time is running out – in addition to this one nutrient there are another 60 to 90 which sustain and support our food production. The future of our trading partners, the future of agriculture and the future of your grandchildren are intrinsically linked. They are all connected inescapably to nutrient flows.

Available nutrient means food production and food production requires good soil – and soil is the mother of us all.”

Significantly, phosphate fertiliser application is an inefficient way of providing phosphorus for plants to convert into food. Cordell’s data show that actual crop uptake from applied fertilisers can be as low as 10-30 per cent, with the balance either locked up in the soil in a bio-unavailable form, or washed off, causing eutrophication of the waterways it flows into and even contributing to damage to Great Barrier Reef. By the time the food reaches the consumer, only two per cent of the phosphorus in the fertiliser remains.

For broad acre farmers, the problem will be how to produce crops using fertilisers made from lower quality phosphate rock in the future, as supplies of quality rock dwindle, or how to minimise their use of phosphate-based fertilisers.

Organic P problem

One solution is to farm more organically, drastically reducing the demand for complete phosphate-based fertilisers, although organic farmers are permitted to use rock phosphate. Better soil management, including increasing the carbon content of soil to improve plant uptake of phosphorus, better use plant waste to prevent run-off and leaching, and better timing of the application of fertiliser, are all points to be considered, and all deserving of further research.

IPL is promoting BioPhos as an alternative to other fertilisers for biological or organic farming systems, or farms converting to these systems. It is ” a is naturally occurring rock phosphate that is composted with liquid fish nutrients generated from wild catch fish waste, carbon sources and select naturally occurring fungi”. Yet Heydon says its use is not likely to reduce overall phosphate demand. The rock phosphate is derived from the same sources as the phosphate for IPL’s other phosphorus fertilisers. It seems likely Biophos is a move by IPL to capture the organic farming market.


An alternative to fertilisers is the reintroduction of phosphorus to the soil through the application of biosolids. Biosolids – the polite term for animal excreta, particularly human excreta – is used extensively in China and Japan, but surprisingly is starting to gain favour in Australia. Approximately 150,000 dry tonnes is applied to farmland each year, usually surface spread and then incorporated mechanically into the soil.

Dr Michael Warne is Principal Research Scientist at CSIRO Land and Water with expertise in biosolids. Biosolids are derived from human waste through waste water treatment plants. In Australia, they are used predominantly on dry land farming – wheat, sugar cane, oats, he says, and are not on vegetables, fruit, dairy or grapes.

Most Australian states produce biosolids, which vary in texture from wet cake – up to 70% water, (NSW) down to very dry -approximately 5% moisture (SA). Each state has its own guidelines for the application of biosolids, which must be incorporated into the soil within 24-48 hours of delivery.

“Farmers have all sorts of reasons for using biosolids, but mainly because they see financial and crop yield benefits,” says Dr Warne. “Those that are allowed to use them and can obtain them love biosolids. However, some people don’t like them. In WA, farmers who were originally all for using biosolids, but had low lying flood-prone land, were not permitted to apply them. They then became very strong opponents of biosolids.”

Strangely enough organic farmers, who are allowed under certification to use rock phosphate, are not permitted to use biosolids in Australia.

While biosolids are an alternative to commercial fertilisers, they are not the whole solution. Humans do excrete almost all of the phosphorus found in the food they eat, but Cordell points out that is only two per cent of the phosphorus originally applied as fertiliser. “Therefore, even if 100 per cent of human excreta were recirculated, Australia would still have a substantial phosphorus deficit.”

She says there are no easy answers to the peak phosphorus problem, only questions, for which no coordinated research either internationally or nationally is being undertaken, and the consequences for the future of farming and for food security are being ignored by policy makers.

The Problem of Western Sahara rock phosphate

Western Sahara is located in Northern Africa, bordering the North Atlantic Ocean, between Mauritania and Morocco. It is a very arid area but is rich in phosphates in the Bou Craa region. Consequently, Western Sahara is the world’s largest supplier of quality phosphate rock, with reserves of around 5700 million tonnes. Even the US, which has reserves of just over 1000 million tonnes, imports rock from Western Sahara, which is controlled by Morocco which has occupied Western Sahara since 1975.

The official status of Western Sahara is as “a non-self-governing territory” by the United Nations. The government in exile, the Sahrawi Arab Democratic Republic, disputes Morocco’s control of the territory. Morocco has been repeatedly criticised for its actions in Western Sahara by international human rights organisations such as Amnesty International, Human Rights Watch, and the World Organization Against Torture. Many of the nomadic indigenous people, the Sahrawis, fled under bombardment to refugee camps in south western Algeria, and the government has encouraged Moroccan citizens to relocate to the territory, creating a state-dominated economy with the government as the single biggest employer. The Moroccan state phosphate company OCP’s facility at iat Bou Craa is connected by an enormous conveyor belt which transports the phosphate rock 100 kilometres to El Aaiun harbour.

Trading with Morocco for phosphate rock has been condemned by the UN, and several Scandinavian countries have considered boycotting imports from Morocco. Both IPL & CSBP source some of their phosphate rock from Morocco, and a spokesperson for DFAT said Australia does not ban the importation of phosphates from Western Sahara.

“The UN has not imposed restrictions on the trade (UN Security Council sanctions), and we are not aware of any country which maintains autonomous sanctions against the trade,” she said.

“However, we are conscious of the status of Western Sahara as a
non-self-governing territory. DFAT draws companies’ attention to the international law considerations involved in importing natural resources sourced from Western Sahara, and recommends that companies seek legal advice before importing such material.”

IPL says there is currently no alternative source for the high-grade phosphate rock imported from Morocco to manufacture SSP to Australian standards. “All Australian SSP producers use some rock from Western Sahara,” Neville Heydon says. “Without rock from the region, it is unlikely that Australian manufacturers could produce the one million tonnes of SSP farmers require each year to maintain productivity and international competitiveness. IPL’s ability to maintain production at its SSP plants would also be in doubt.”

CSBP sources the majority of its phosphate rock from Western Sahara, “as its properties enable CSBP to continue manufacturing single superphosphate and meet its rigorous environmental and quality standards,” says MD, Ian Hansen.

“Wesfarmers and CSBP have engaged in dialogue with opponents of the import of phosphate rock through Moroccan-based suppliers from Western Saharan deposits, including Mr Kamal Fadel, Polisario Representative to Australia. We continue to monitor the United Nations’ efforts to resolve the dispute over Western Sahara.”

The Australian Western Saharan Association believes the trade in phosphate sourced in Western Sahara, but sold by Morocco should be put on hold until the conflict over Western Sahara is resolved.

“So long as Morocco is able to exploit the natural resources of the country it occupies, it has no motive to settle the issue,” Cate Lewis, who is also International Coordinator Western Sahara Resource Watch, said.

“If the three Australian phosphate importers acted together, they would have quite a significant effect on Morocco. Even more so if they teamed up with the two importers in New Zealand. Morocco desires international respectability and is sensitive to being ostracised openly. So we think it would be a worthwhile action.”

She said farmers could put pressure on the Federal government and the fertiliser manufacturers. “If Australia were to impose a trade embargo on the product, it would certainly make it easier for the fertiliser companies.

“If a farmers’ group were to insist that Australia boycotts this phosphate trade, it would certainly help persuade the government, I should think, because one of the reasons they are loath to act is that they don’t want to upset the farmers. It would be a great gesture if the farmers took the initiative here.”


Bou Craa phosphate mine, Western Sahara


(Photos courtesy John Toerdai, Western Sahara Resource Watch)

©Sue Cartledge 2009

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