Fighting Peak Phosphorus


Earth’s phosphorus is being depleted at an alarming rate. At current consumption levels, we will run out of known phosphorus reserves in around 80 years, but consumption will not stay at current levels. Nearly 90% of phosphorus is used in the global food supply chain, most of it in crop fertilizers. If no action is taken to quell fertilizer use, demand is likely to increase exponentially.

(Prud’Homme, 2010, from Schroder et. al., 2010)

A simple program of smart demand reduction and increased organic waste recycling, supplemented with mining exploration in probable deposit areas, can delay, if not completely avoid, a peak in phosphorus production for several decades. However, it is imperative to take action now. There was a time when humans operated totally self-sufficient farms, tilling the same land for years by managing waste effectively, by simply making sure that everything that came out of the land eventually went back into it. In such a closed-loop scenario, phosphate would have the capacity to be reused approximately 46 times as food, fuel, fertilizer, and food again [1]. In the fertilizing techniques that dominate today, which involve the annual application of phosphate-enriched chemical mixtures on top of nutrient-starved soil, phosphorus is used exactly once, then swept out to sea. This practice is simply unsustainable. Our ancestors learned the importance of conserving nutrients through necessity: if they could not make the soil yield, they would starve; there were no second chances. The world has a chance, now, to learn this lesson again, before it’s too late.

History

The United States is unique in that it is both a wealthy, industrialized nation at the forefront of technology, and an agricultural powerhouse with the third-largest population in the world. In the 1970s and early 1980s, during the early years of the Green Revolution, the US’s production of food commodities shot up, as did their use of artificial nitrogen-phosphorus fertilizers. The USSR followed a similar agricultural path, and as a result, worldwide phosphorus production grew from about 8 Mt/y in 1960 to over 20 Mt/y at its peak in the mid-1980s. Following this milestone, the world actually entered a period of reduced production and use that lasted until just a few years ago. While some have speculated that peak phosphorus production has already been reached, it seems more likely that the relatively short dip in production was merely the a coincidence of reduced use in the wake of the USSR’s collapse and more efficient practices being adopted by US farmers, while the rest of the world’s food production was still catching up.

The world has caught up. In the past 30 years, the US has gone from the world’s top phosphate consumer to the third largest, and now exports more phosphorus than it consumes (World Bank, 2012). Most of the new phosphorus use has been in India and China, which, together, now account for over 45% of the world’s total consumption . However, the United States’ total food production has not faltered at all in that time; in fact, it has improved significantly . This is due to more efficient farming practices and greater utilization of organic waste, as well as increased awareness of the problem among today’s farmers. The same shift towards efficiency and moderation has occurred among farmers in the EU as well, and it may be extrapolated that this is the natural progression followed by agricultural countries as they mature past rapid expansion to more stable, sustainable production levels. The biggest challenge, then, is not cutting back on phosphorus use in developed countries, but reigning in the growth of demand in rapidly developing ones.

Saving Phosphorus

Mission 2016 proposes a 3-part plan to cut back on global phosphorus consumption, especially in areas with growing demand, increase efforts to recycle phosphorus in human and animal waste, and assess new potential mining zones.

1. Reduce demand through smarter fertilizer use

It is the opinion of Mission 2016 that the single largest problem with phosphorus fertilizer use is overuse. The amount of phosphorous actually required to maintain a farm is highly variable, and depends on factors such as soil conditions, crop type, crop history, geography, and weather patterns. This makes it very difficult for farmers, especially those operating small, independent operations in developing countries, to accurately assess their fertilizer needs, and leads to superfluous application. Excess fertilizer is not only wasteful, it runs off into lakes, rivers, and oceans, where it causes massive, unnatural algae blooms. These photosynthetic microbe colonies cover huge areas of water, then die off, leaving behind sediment that blocks sunlight and destroys the aquatic ecosystems beneath them.

Experienced farmers can learn the most efficient amounts of fertilizer to use through years of experience, which is part of the reason agriculturally mature nations have better fertilizer-to-yield ratios than developing nations. In addition, scientific, quantitative data analysis can be applied to farmland to determine the proper amount of fertilizer to use in a given situation. The Wisconsin phosphorus index is an example of a tool, developed jointly by the government and the University of Wisconsin and optimized for a specific region. It includes SnapPlus, a free software that allows farmers to estimate their optimal fertilization plan from home .

This program will be used as a model for a worldwide campaign, focusing on the fastest-developing, highest consuming nations. For this purpose, a United Nations (UN) task force will be established within the Food and Agriculture Organization, within the Economic and Social Development Department, comprised of approximately 200 agents with agricultural and educational experience with a budget of $30 million per year. The average UN salary is approximately $119,000 per year , and an additional 6 million USD/a will be allocated for transportation, supplies, and expenses. The task force will develop a template, similar to the one developed by the University of Wisconsin, which can be adapted to specific regions around the globe. It will work closely with state and regional governments and agricultural institutions to provide accessible information for all local farmers, even those who do not own or have access to a computer. The force should emphasize the economic, environmental, and long-term benefits of sustainable phosphorus use to its clients. While it will not work directly with farmers, it will aim to instill the ideas of conservation and sustainability into the local bodies responsible for the agricultural health of their communities.

A recent China Agriculture University study found that northern Chinese farmers use about 92 kg of phosphorus fertilizer per acre, of which only 39 kg are removed as crops. This means 53 kg, fully 58% of phosphorus, is not utilized and ultimately lost into the environment (21). As China is the largest phosphorus consumer in the world, with 5.2 Mt consumed in 2009 alone , reducing the country’s phosphorus waste by even half would save the world over 1.5 Mt of phosphorus (3.45 Mt phosphate) per year.

2. Stretch current supplies further through recycling

The primary means by which phosphorus is reintroduced to the environment post-consumption is animal waste. Though manure is still used extensively around the world as fertilizer, human waste that was once returned directly to the soil is now collected in municipal waste facilities and often released to the ocean. Although most of the recoverable nutrients are currently lost, centralized municipal collection facilities offer a means to recycle large quantities of phosphorus with relatively little effort.

Struvite, or magnesium ammonium phosphate, is a hard, clear crystal that occurs naturally when ammonium-producing bacteria break down the urea in urine. It’s the substance that causes kidney stones, and for centuries, it has been the bane of sewage system operators the world over, forming hard, rock-like crystal deposits on the inside of pipes that can build up and block off flow. However, struvite is a benign, non-toxic substance, and it can be used as a rich, slow-release phosphate fertilizer. In fact, struvite outperforms diammonium phosphate (DAP), the most widely-used fertilizer today (15), on a unit-for-unit basis in terms of dry matter production, phosphorus uptake, and extractable residual phosphorus (14). Although struvite is preferable to DAP in most circumstances, in the past, it has only been used for high-value crops due to its higher cost (14).

In the past decade, phosphorus recovery has been the subject of intense research, and there are several new, economical methods by which it can be accomplished, many involving struvite formation. One technique, developed by University of British Columbia professor Don Mavinic, involves a cone-shaped reaction chamber in which small struvite crystals combine with magnesium, ammonium, and the phosphorus in wastewater on its way to a biosolids processor (X). The crystals grow until they are large enough to be collected by a filter and removed. These systems prevent struvite buildup in pipes, prevent phosphorus pollution in water basins, and provide valuable, usable phosphorus fertilizers. A company, Osatra Nutrient Recovery Technologies, Inc., was founded around the technology, and the struvite fertilizer the process creates is marketed as Crystal Green® (X). Another technology involves using charged, molecular “templates” to induce the formation of large crystals in liquid manure (X). Struvite-based methods can recover upwards of 90% of wastewater phosphorus (X,Y). Biological capture is a promising area of research as well, and involves cultivating phosphorus-hungry algae in the phosphate-rich side streams of waste treatment facilities, yielding 60-65% recovery rates (X). A third possible recovery method is through thermochemical treatments, which burn waste sludges to ash and then convert the contained phosphorus to bioavailable forms free from toxic heavy metal loads; this method can feasibly reach 100% recovery (20, X).

As is the case with improving fertilizer efficiency, the European Union, Canada, and the US have led the world in phosphorus recovery. By 2007, 53% of sewage sludges in the EU were already reused in agriculture , and in 2009, Sweden passed legislation to have at least 60% of its total phosphorus streams from wastewater diverted for agricultural use by 2015 (18, X). By 2009, Osatra struvite systems had been installed in Edmonton, Alberta; Portland, Oregon; and York, Pennsylvania, and the company had plans to expand to the UK and the Netherlands. The progress made by these countries is significant, but the greater problems, and potential gains, lie with China, India, and other fast-developing areas. If these areas begin implementing significant amounts of high-quality, renewable phosphate fertilizer into their supply chain early during their agricultural maturation, their demands for imports will not rise nearly as dramatically as they could.

To this end, Mission 2016 will establish a domain of the Open Information Exchange to deal specifically with phosphorus recycling techniques. As established above, there is a plethora of scientific research being done on the subject, although most of it is taking place in Europe. Working in conjunction with the governments and relevant research bodies of the world’s fastest-growing phosphorus consumers, the task force will promote the development of economical, efficient applications of new and cutting-edge recycling technologies that are tailored to specific regions. Its goal will be to reduce their waste and increase their recycling, and it will emphasize the economic potential of such systems: one analysis by the Stockholm Environmental Institute (SEI) estimated the potential of phosphorus wastewater recovery in East Asia at more than 625 million USD annually (22). In addition, the Strategic Minerals Association (SMA) of the UN, described in the Protocol section of our solution, will work to draft a treaty between the top phosphorus consumers in the world, currently China, India, the United States, the European Union, and Brazil, to set a target of 50% total phosphorus recovery from wastewater by 2025. The SMA will also provide investment capital in the form of loans to municipal waste processing companies looking to install phosphorus-recycling technology.

However, the most critical applications of waste recycling will be in places that lack access to conventional sources of phosphate fertilizers. Many farmers in sub-saharan Africa simply can’t afford artificial fertilizers, if they can even find them; yet the same SEI study estimated the value of recoverable fertilizers from waste in the region at 800 million USD (22). According to a 2009 study by renowned soil scientist Pedro Sanchez, the average Kenyan farmer uses just 8 kg of phosphorus and 7 kg of nitrogen per hectare, far less than the 14 kg P and 93 kg N used in the US and the staggering 92 kg P and 588 kg N used in China. This is not efficient use, it is insufficient use, and it causes food shortages and starvation. Magnesium waste scrubbing (struvite-forming) technologies would appear to be an easy solution in these cases, too, but kind of infrastructural investment that the technology represents requires a level of maintenance that impoverished areas simply can’t support. Without proper upkeep, the struvite filters can become clogged and dirty, breeding malignant bacteria and doing more harm than good (X).

For poor, underdeveloped communities, better waste-recovery solutions are often low-tech, small-scale affairs. SEI has explored simple, outhouse-style toilets, able to be constructed locally and maintained with minimal skill or effort. The temporary installations will collect waste for a number of years, then transition to compost pits suitable for planting trees. Some variants include a method for collecting and storing urine, which may be used as a fertilizer for greens, onions, maize, and many other crops. The Swiss Federal Institute of Aquatic Science and Technology (EAWAG) has been applying a similar minimalist approach in Nepal, where a simplified struvite extraction reactor of their own development turns urine into a usable, dry powder fertilizer. As of 2010, the process was not totally refined, but it had been met with tremendous local support.

The UN, through the World Food Program (WFP), will fund efforts to implement these technologies in sub-saharan Africa and elsewhere, beginning on a small scale. In 2010, the Bill and Melinda Gates foundation pledged 3 million USD in a grant to the EAWAG towards a test sewage-recovery program for sub-saharan African communities (23). The WFP will match that amount to start, to conduct a similar, 4-year pilot program. At the conclusion of the program, or in the middle should it prove extraordinarily successful, the WFP will convene to discuss the results and determine the long-term viability of the technology. It will allocate additional funds for a permanent organ of the WFP dedicated to fertilizer recovery from waste. Hopefully, once the concepts are proven, private charities will appropriate a significant portion of the cost, as they have in the past .

3. Explore new mining areas to determine actual total reserves

According to some peak phosphorus alarmists, the world is running out of viable reserves in the very near future (EU paper). Their estimates often use United States Geological Survey (USGS) data on total world reserves, but each year, USGS estimates change, usually to expand reserves, and sometimes dramatically. The largest discoveries as of late are in Morocco or the Western Sahara, and there is as of yet no definitive world total of high-grade phosphate deposits. By determining the actual amount of phosphorus available, more accurate plans can be made for a sustainable future. Currently, there is far too much uncertainty about how much recoverable phosphate the earth has left.

The USGS has extensive geological resources at their disposal, and they have mapped out the mineral profiles of foreign countries several times in the past. Mission 2016 advises that the World Trade Organization (WTO) facilitate treaties between the US and other countries in which the USGS works with other governments to map geological profiles worldwide, creating a database of areas with potentially tappable mineral reserves. Following this initial study, increasing supply becomes a free market solution, as corporations use this information, conduct follow-up studies, and open new mines. This will be a beneficial situation for all parties involved, and in the end will be good for the world.

Phosphorus is vital for life on Earth – and we’re running low

Phosphorus is an essential element which is contained in many cellular compounds, such as DNA and the energy carrier ATP. All life needs phosphorus and agricultural yields are improved when phosphorus is added to growing plants and the diet of livestock. Consequently, it is used globally as a fertiliser – and plays an important role in meeting the world’s food requirements.

In order for us to add it, however, we first need to extract it from a concentrated form – and the supply comes almost exclusively from phosphate mines in Morocco (with far smaller quantities coming from China, the US, Jordan and South Africa). Within Morocco, most of the mines are in Western Sahara, a former Spanish colony which was annexed by Morocco in 1975.

The fact that more than 70% of the global supply comes from this single location is problematic, especially as scientists are warning that we are approaching “peak phosphorous”, the point at which demand begins to outstrip supply and intensive agriculture cannot continue to provide current yields. In the worst case scenario, mineable reserves could be exhausted within as little as 35 years.

So what is going on – and how worried should be?

Natural limits

In nature, phosphorus only exists bound to oxygen, which is called phosphate. It is in this form that it is mined. Chemists can remove the oxygens bound to it to get elemental white phosphorus, which glows in the dark, but it is so unstable that it spontaneously ignites on exposure to air.

Phosphate easily diffuses through soil or water and can be taken up by cells. When phosphate meets free calcium or iron, they combine to give highly insoluble salts.

In the first half of the 19th century, Justus von Liebig popularised the law of the minimum for agriculture, which states that growth is limited by the least available resource. It was soon discovered that this was often some form of phosphorus.

As a consequence, bones – comprised mostly of calcium and phosphate – from old battlefields were dug up to use in farming. Guano, large accumulations of bird droppings, also contains high concentrations of phosphorus and was used to fertilise crops. But supplies of this were soon depleted. As demand increased, supplies had to be mined instead.

But this applied inorganic phosphate fertiliser is highly mobile and leaches into watercourses. In addition, phosphate rock weathers and is also ultimately washed into the ocean where it either deposits as calcium phosphate or is taken up by marine organisms who also eventually deposit on the ocean floor when they die. Consequently, terrestrial phosphorous doesn’t really disappear, but it can move beyond our reach.

Natural wastage

To complicate matters further, even the phosphorous we can use is largely wasted. Of the phosphorus mined as fertiliser, only a fifth reaches the food we eat. Some leaches away and some is bound to calcium and iron in the soil. Some plant roots have the ability to extract the latter, but not in large enough quantities to retrieve all of it.

In addition to these inorganic forms, phosphate is also converted into cellular compounds, creating organically-bound phosphorus, such as phospholipids or phytate. After the death of an organism, these organic phosphorus compounds need to be returned into the useable phosphate form. How much organically-bound phosphorus is present in soils depends on the number and activity of the organisms that can do this.

Phosphorous boosts crop yields. Shutterstock

Agricultural soils are usually rich in inorganic phosphorous while in undisturbed ecosystems, such as forests and long-term pastures, organically-bound phosphorus dominates. But agricultural land is often depleted of phosphorus during harvest and land management practises such as ploughing, hence the addition of phosphate-containing fertilisers.

Spreading manure and avoiding tillage are ways of increasing microbial abundance in the soil – and so keeping more phosphorus in an organically-bound form.

The risks of peak phosphorous can be countered with some simple solutions. Eating less meat is a start as huge amounts are used to rear livestock for meat. The chances are that agricultural yields are limited by phosphorus availability and will be further stretched as the global population grows.

Humans are themselves wasteful of phosphorous, as most of what we take in goes straight out again. Fortunately, technologies have been developed to mine phosphorus from sewage, but at present are too expensive to be practical.

Peak phosphorus does not mean that phosphorus will disappear, rather that the reserves with mineable high concentrations are depleting. Instead, we are increasing the background concentrations of phosphorus and adding it to the ocean floor. More sustainable phosphorus use requires a greater appreciation and understanding of the many organisms that make up soils – and the part they play in phosphorus distribution – or we may no longer be able to feed the world at an affordable price.

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(Development Policy Review Network, 2011)
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