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Published: 2010

Peak fertilizer

Kath Kovac

To grow food, you need nutrients: there’s no getting around it. With the Food and Agriculture Organization predicting that the world will need to produce 70 per cent more food for the 9.1 billion people that will populate the planet by 2050, alarm bells are ringing about the issue of nutrient supply.

The NSW DPI’s Centre for Recycled Organics in Agriculture has shown that using garden organic compost for intensive vegetable production produces yields similar to the conventional practice of using poultry manure and inorganic fertiliser. Using compost also significantly increased soil organic carbon and soil quality.
Credit: K. Y. Chan

What can we do when the traditional supplies of essential fertiliser nutrients dwindle, become prohibitively expensive and can no longer satisfy demand?

The only solution seems to be a return to the familiar concept of ‘reduce, re-use and recycle’. We need to reduce fertiliser use and nutrient losses to the environment. Plus, we need to recycle and re-use nutrients wherever and whenever we can.

The fertiliser problem

Of the three main fertiliser nutrients – nitrogen (N), phosphorus (P) and potassium (K) – N is manufactured using natural gas to make ammonia, and P and K are mined from the Earth.

According to the International Fertilizer Industry Association, 97 per cent of the world’s N fertiliser is made using natural gas as the energy source. With natural gas supplies predicted to run down over the next 25 to 50 years1, N fertiliser prices will continue to rise, reflecting rises in gas prices. By 2030, although Australia’s natural gas production is predicted to increase four-fold, exports will rise and will more than double domestic consumption.2 This could leave us with less gas to make our own fertiliser, and facing the problem of having to import it at an even greater cost.

Phosphorus fertiliser is manufactured from phosphate rock, and K fertiliser is made from potash – both non-renewable sources. Although K supplies don’t seem to be causing too much concern yet, it’s a different story for P. Around the world, phosphate rock quality and quantity is declining. Experts tip P supply to peak by 2030,3 with known reserves predicted to be depleted within 50–100 years.

Apart from our growing population, the trend to biofuel use as an alternative to fossil fuels is also hugely increasing global demand for fertilisers.

Dwindling nutrient supplies are not the only problem associated with fertiliser use. Crops can only take up a certain amount of the nutrients applied to them, and much is lost to the environment; industry point-source pollution and urban sewerage systems also add to nutrient pollution levels. Fertiliser runoff to waterways and oceans causes eutrophication and damage to marine environments. Plus, nitrous oxide, a potent greenhouse gas, is produced by volatilisation of fertiliser N and by processes used to remove N from sewage effluent.

Tractor applying anhydrous ammonia fertiliser to a field at Harden, NSW. Australia currently uses about one million tonnes of nitrogen fertiliser every year, with sales doubling in the last 20 years (data from the Fertilizer Industry Federation of Australia).
Credit: Gregory Heath, CSIRO

Fighting nutrient loss

Commissioner of the Natural Resources Commission, Dr John Williams, says that movement of fertiliser from crops is a big problem in Australia.

‘Groundwater is a big issue in terms of N leakage, as it gets washed into the environment,’ he says.

Cutting back on the amount of fertiliser applied to crops – and developing crops that use N more efficiently – are two ways of reducing the high levels of nutrients from agricultural sources that make their way into the ocean.

CSIRO Sustainable Ecosystems is developing a system to reduce N fertiliser use in sugarcane crops by accurately calculating how much to apply. Lead researcher, Dr Peter Thorburn, says that the ‘N-Replacement’ method balances the amount of N fertiliser applied to a crop against the amount of N both removed by the previous crop and lost to the environment.

‘In field trials, N applications were 35 per cent lower when using N-Replacement, and about 50 per cent less N was lost to the environment,’ says Dr Thorburn. ‘Plus, sugar yields actually increased in trial crops that were given less N.’

A CSIRO Plant Industry project, lead by Dr Ian Fillery, is seeking to reduce N loss by screening wheat varieties to find those that uptake N most effectively.

‘Recovery of fertiliser N by wheat is typically incomplete. If we can find a high-performing variety that takes up the most N possible, then less will be lost to the environment,’ says Dr Fillery.

CSIRO’s ‘N-Replacement’ method reduces N fertiliser use in sugarcane crops by accurately calculating how much to apply.
Credit: CSIRO Sustainable Ecosystems

Credit: Paques B.V.

Nutrient re-using and recycling

As well as trying to reduce N inputs and losses on-farm, we have to recycle and re-use nutrients. One source that is infinite – as long as humanity is around, that is – is sewage.

One way of recycling nutrients from sewage is by reusing biosolids – the dry, stable matter that remains after sewage has been processed. Biosolids contain high proportions of N, P and K, and are used across Australia in agriculture, composting and land rehabilitation.

After biosolids are removed, the effluent liquid can be treated and recycled. Ideally, most of the remaining nutrients should be recovered from wastewater before it is finally released into receiving waters and the nutrients are lost to the ocean. Researchers around the world are trying to develop ways to achieve this. Dr Williams says, however, that we haven’t made enough progress in this area.

‘Lots of nutrients are still going into ocean outfalls of sewerage systems,’ he says. ‘We are putting out millions of tonnes of very valuable material, like P, into the sea, instead of recycling it.’

A United States company has invented a way of recovering N in the form of solid ammonium carbonate from wastewater. The anaerobic digester-based process also makes biomethane gas.

‘Our system uses no chemicals and only a small amount of waste heat and power,’ says Mr Dennis Burke, head of the Environmental Energy & Engineering Company. ‘And, unlike other ammonia removal and recovery processes, it is profitable to recover ammonia as an inorganic fertiliser derived from an organic source.’

A high proportion of P, and some N, can be also be recovered by precipitating magnesium ammonium phosphate – commonly known as struvite – from sewage wastewater and intensive livestock waste. Depending on the form of the struvite product, it can be a suitable substitute for commercial fertilisers. Professor Tony Priestley, recently retired CSIRO scientist and water quality expert, says that struvite production is a feasible technology, with a plant in Canada already producing struvite reactors.

However, Professor Priestley cautions that we still need to look at other sources of nutrients.

‘Wastewater is just one source; it won’t save the planet, as the amounts of nutrients in wastewater are not that high,’ he says. ‘If you could recycle all the N and P from every human, you’d get about 16 per cent of the N and 21 per cent of the P fertiliser that is manufactured worldwide. If you could also recycle all the N and P from farm animals, you’d get double that. But, the trick is in capturing all of the waste in one spot.’

This reactor in the Netherlands recycles industrial wastewater to produce struvite, a suitable substitute for commercial fertilisers.
Credit: Paques B.V.

Where to from here?

It’s clear that fertiliser use can be cut back and made more efficient, and that technology exists to recover nutrients from wastewater. Both of these aims are desirable – and necessary – from both an economic and an environmental viewpoint. But, to make the process a reality, we need some change in thinking and some governmental action to implement national solutions.

Dr Williams suggests that instigating compliance with standards could help with the issue of diffuse pollution from agricultural activity.

‘We’ve brought point-source pollution — that from industrial plants, milk factories and the like – under control with good legislative frameworks,’ he says. ‘But, it’s harder to regulate diffuse pollution; changes in practise have to be made. We need incentive programs, like those to reduce pesticide use in the cotton industry – they knew they could lose their licences if they didn’t comply, so they did so.’

Dr John Radcliffe, Chairman of the Water Forum of the Australian Academy of Technological Sciences and Engineering, thinks that profits will probably be more important than legislation, especially in regard to P recovery.

‘Ultimately, technological solutions to reclaim phosphorus at a competitive market price in relation to whatever becomes the ultimately rising price of “natural” phosphorus will be the motivator,’ he states. ‘I don’t think you can compulsorily legislate for these policies – they must ultimately have a market rationality.’

Mr Dennis Burke agrees. ‘The advantage of our N recovery process is that we can make money at it – the only way to survive in the US,’ he stresses.

Professor Priestley is adamant that the government needs to come to grips with the problem of phosphorus supply.

‘It hasn’t entered the political imagination at all; no-one seems to have heard of peak phosphorus,’ he says. ‘They debate on population growth and how to feed everyone, but this takes energy, water and nutrients; no-one has thought through what’s required.’

Author and science writer, Julian Cribb, is trying to overcome this; he is calling for the implementation of a National Nutrient Plan to maximise nutrient re-use and reduce our dependence on fertiliser.

‘Every human generation, except for the last two, have recycled their nutrients back into agricultural systems,’ he says. ‘The last two generations are the first to waste them completely. We’ve created an unsustainable system; using nutrients up and then throwing them away.’

1 Foran B and Poldy F (2002). Future Dilemmas: options to 2050 for Australia’s population, technology, resources and environment. CSIRO Sustainable Ecosystems.
2 Syed A, Melanie J, Thorpe S and Penney K (2010). Australian energy projections to 2029–30. ABARE research report 10.02, Australian Bureau of Agricultural and Resource Economics.
3 Cordella D, Drangerta J and White S (2009). The story of phosphorus: global food security and food for thought. Environmental Change 19:2, 292–305.

Published: 2010

Empowering vision

Cynthia Karena

Educational filmmaker and sustainability advocate, John Liu, has a knack for effectively communicating the complex in ways that make people sit up and take notice. A key to his success is leveraging the power of the image to inspire hope and a commitment to action.

John Liu in Rwanda – <i>Hope in a Changing Climate</i> documents local communities and government working together to rejuvenate the land.
John Liu in Rwanda – Hope in a Changing Climate documents local communities and government working together to rejuvenate the land.
Credit: John Liu

John D Liu’s mission is to make it easy for people to understand climate change.

‘The issue is knowledge. For either the public or for policy makers, ignorance is a good excuse,’ says Mr Liu, founder of the Environmental Education Media Project (EEMP), which produces audiovisual environmental education materials for broadcast and educational audiences.

For more than ten years, the project has been documenting best-practice methods for large-scale restoration of damaged or destroyed ecosystems.

‘If (people) don’t know what to do, they are unlikely to be able to do much,’ says Mr Liu. ‘But if we know that it is possible to rehabilitate large-scale degraded ecosystems and we don’t do it, then we have crossed a line, because our knowledge is responsibility.’

An American with a Chinese father and an American mother, Mr Liu has lived in China for more than 30 years. He trained as a journalist in the United States, and moved to China to help open the CBS News Bureau in Beijing in 1979.

After a decade of living in China, Mr Liu became concerned about the levels of pollution and the rapid pace of development.

With his ‘knowledge brings responsibility’ philosophy, he founded the Environmental Education Media Project for China (the precursor to EEMP) and has been engaged in researching, documenting and educating people about ecology ever since. As an environmental filmmaker and ecological field researcher, he has produced and directed documentaries for CBS, National Geographic and the BBC.

John Liu on location in the 1990s, soon after establishing his environmental education media project.
John Liu on location in the 1990s, soon after establishing his environmental education media project.
Credit: John Liu

In 2006, Mr Liu was named the Rothamsted International Fellow for the Communication of Science. Rothamsted – a non-profit organisation working towards sustainable agriculture in developing and emerging countries – supports his PhD work with the Soil Sciences Department at the University of Reading in the United Kingdom.

Mr Liu is also a member of the Steering Committee of the Global Forum on Media for Development, and an Associate Professor at George Mason University’s Center for Climate and Society in the US.

Stories of hope

Mr Liu says most policy makers and the public assume that the human impact on climate is limited to the copious emissions of carbon dioxide and other greenhouse gases generated by fossil fuel combustion over the past century or so.

‘The problem with this is that it is only partially true,’ he says. ‘Human impact on the climate began long before egregious emissions of CO2 and other greenhouse gases, when human beings began to reduce biodiversity, biomass and accumulated organic matter. These impacts are exacerbated by egregious emissions.’

Re-balancing the world’s carbon equilibrium, according to Mr Liu, is not just a matter of reducing carbon dioxide emissions.

‘If we restore all degraded land on the entire planet as well as reduce emissions, you can extrapolate massive carbon uptake, [as well as] re-regulated hydrological flows, increased fertility and productivity, and the ability to ensure that the highest level of genetic diversity possible survives into future generations,’ he says. ‘That seems like a much more comprehensive result.’

EEMP’s most recent documentary is Hope in a Changing Climate, filmed on location in China, Ethiopia and Rwanda.1 The film aims to demonstrate that damaged ecosystems and degraded land can be restored to health, and that such an outcome economically improves the lives of local people.

The segment on China’s Loess Plateau proves the point, with location footage showing how a barren, brown landscape covering an area the size of Belgium was transformed into a functioning, green ecosystem where rainfall infiltrates, water is retained and crops are readied for export. Importantly, this has enabled local communities to prosper.

Hope ... also interviews world leaders, bankers, students, presidents, journalists, scientists and local people. According to the film’s website, the Government of Rwanda has adopted a new national land-use policy based on EEMP’s presentations and analysis.

The film aired on BBC World last year, and screenings were held for world leaders at the Copenhagen climate change summit.

Reversing the damage

Degraded farmland in developing countries may be one of the best opportunities we have to reverse the trend toward reduced ecological function, says Mr Liu.

‘What human beings have done historically to damage the environment can be understood rather simply. We have interrupted evolutionary trends. This has resulted in reducing biodiversity, which has caused a reduction in biomass, which has in turn caused a reduction in the accumulation of organic matter. These changes have caused disruptions to fundamental systems that all life relies on.

John Liu’s documentation of the transformation of China’s Loess Plateau from barren landscape (top) to fertile oasis (bottom) has inspired communities in other ecologically damaged areas.
John Liu’s documentation of the transformation of China’s Loess Plateau from barren landscape (top) to fertile oasis (bottom) has inspired communities in other ecologically damaged areas.
Credit: John Liu

‘Through our ignorance, we have reduced gas exchange through photosynthesis, lowered nutrient recycling through the decay and transformation of each generation of life, and massively disrupted the infiltration and retention of rainfall in the biomass and in the soils.

‘If we return vegetation to degraded landscapes we can sequester large amounts of carbon from the atmosphere. This is done through photosynthesis. If we return vegetation, we also can lower temperatures because of shade, and we can increase soil moisture and relative humidity by restoring microclimates below vegetated canopies.

‘The Global Partnership for Forest Landscape Restoration has roughly estimated that one billion hectares of the Earth have been degraded and could be restored. This represents a huge potential, through understanding and positive work, to improve what is now a quite bad situation.’

Urban responsibility

The principles of conserving biodiversity and utilising biomass and accumulated organic matter are not just applicable to rural areas, says Mr Liu.

He sees the Earth as made up of five different landscape types; urban landscapes, pristine or functional landscapes, agricultural landscapes, industrial landscapes and large degraded landscapes.

‘In urban and industrial areas we have in many cases created “dead zones” without any biology. This is not true of all cities. In great cities [such as] London, Beijing, Tokyo, Paris and New York, there are lovely parks, but the buildings, the streets, the parking lots, the factories and businesses are mostly not designed to include these principles.’

Mr Liu says that if you lower biodiversity, biomass and organic matter, you get elevated temperatures. Another impact of losing biomass and organic matter to impervious ground cover such as pavement is the loss of capacity to retain and infiltrate rainfall. This results in flooding during rainy seasons. Further, water that would have been captured by living plants and roots during rains is not available to an ecosystem during the dry season.

‘If we understand these principles, and design our cities, our transportation systems and our buildings around them, then we will have a very different, a very liveable and a sustainable future,’ he says.

‘If we continue to fail to learn this, then I think we are in for very serious problems very soon.’

Not ‘them’ – just ‘us’

Australia’s pollution has little impact on the world compared with China or India, which may lead some Australians to feel complacent about the environment. However, this type of thinking suggests an ‘us’ and ‘them’ approach, says John Liu.

‘From my perspective there is just “us”. Humanity is a species. We need to have a species response now to our problems, not suggest that this is “their problem”. It is our problem because we are affecting global systems,’ he says.

Mr Liu gives the example of persistent organic pollutants. These human-made substances travel all over the world and accumulate up the food chain, but the highest concentrations can be found in Inuit peoples who are thousands of miles from any source.

‘Pollution somewhere is pollution everywhere,’ he says. ‘There is no them. Just us.’

More information

Environmental Education Media Project,


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