Tag Archives: Phosphorus

Phosphorus dynamics – mining vs. recycling

Global P consumption in Millions of Tonnes. Data from FAO.

Phosphorus is essential for sustaining humanity, because it is essential nutrient for producing food, and it is often a limiting nutrient for plant growth. Unlike nitrogen, it cannot be fixed from the air, and must be either recycled or mined.

Modern industrial agriculture relies on continual inputs of mined phosphor. How long phosphorus mining can last is quite uncertain. A new assessment of phosphor supplies suggests these are supplies are much bigger than previously thought.

A recent editorial in Nature Not Quite Assured (Oct 27, 2010)writes:

Reserves of the phosphate rock used to make such fertilizers are finite, and concerns have been raised that they are in danger of exhaustion. It has been argued, for example, that data from the US Geological Survey point to the available supplies peaking in as little as 25 years time (see Nature 461, 716–718; 2009). Because there is no substitute for phosphate in agriculture, this might present an urgent and substantial problem. But initial findings from the World Phosphate Rock Reserves and Resources study conducted this year by the IFDC, an international non-profit organization based in Muscle Shoals, Alabama, and formerly known as the International Fertilizer Development Center, suggest that phosphate rock deposits should last for between 300 and 400 years.

Accurate information about phosphate reserves is hard to come by, and the IFDC concedes that more work is needed to hone its estimates. The mining industry, governments and interested researchers should accept the organization’s invitation to collaborate in this process.

The phosphate issue runs beyond gaining assurances that total global supply will meet demand. There remain important concerns that phosphate and other fertilizers are being squandered in some parts of the world, whereas farmers in other regions cannot obtain them at a reasonable cost.

… current fertilizer-production methods fail to maximize the efficient conversion of phosphate rock into fertilizer. The supply of the rock is heavily concentrated in two nations, China and Morocco, on whose good faith the rest of the world relies for its phosphate supplies. That faith has been shaken by extreme price fluctuations in recent years.

Yet the heavy dependence of food production on fertilizers, inequalities of supply and the need for sustainable use of fertilizers — including recycling — are largely missing from discussions on approaches to sustainable development. They were only mentioned in passing, for example, at the United Nations’ world summit on food security in Rome last November.

Hydrologists, soil researchers and food scientists have begun to raise awareness of some of the issues surrounding phosphates. A discussion will be devoted to the topic at the Crop World 2010 meeting in London next week, in which researchers will be joined by industry and government representatives, including John Beddington, the UK government’s chief scientific adviser, who has worked hard to raise political awareness of food-security issues.

These efforts would be strengthened if an international body, such as the UN Food and Agriculture Organization, started to seriously champion the issue of sustainable fertilizer use. The organization already tracks fertilizer demand and supply, and has produced reports on phosphate fertilizer use. It doesn’t have a specific programme for sustainable fertilizers, but its departments of agriculture and natural resources do some work in this area, giving it a base on which to build. It now needs to push this issue out from the sidelines and into the policy-making process that will shape the future of agriculture and sustainable development.

My colleague Arno Rosemarin believes that the assessment is wrong.  He has co-authored another assessment of phosphor supplies, and comments on the nature editorial:

The statement in the IFDC report that we have 300-400 years prior to depletion og phosphorus is based on a zero increase in extraction from now on. The rate of annual increase is presently in fact 3-4%. Extraction will hopefully decrease as we become more efficient, start significant reuse programmes, etc. But this will take decades and no UN governance or monitoring plan is in sight. The food security summits in 2008 and 2009 never mention the word phosphorus. The new data on increased reserves from IFDC are based almost entirely on a recalculation for Morocco giving them 10 times more phosphorus and 85% of the global capacity. But the estimates are based on a hypothetical calculation and economic viability does not figure in the calculation. There are no data on reserves from industry in the calculation since this is kept confidential.

Ecosystem ecologist Jim Elser followed with:

While this seems like welcome news, as Dr Rosemarin notes, the new estimate is entirely based on a revision of estimates for Morocco and seems to be derived from a 20-year old geological report and not on any new geological survey data. It is also important to note that the 300-400 year IFDC estimate for P depletion is a different event than the timing of “peak phosphorus”, which refers to the date when global P production will occur (previous estimates placed this timing for 2030-2040). It is likely that, even if this new reserve number for Morocco is correct and the P ore there is indeed of high quality and accessible, a production peak for P is likely only pushed back by a few decades. In any case, the key issue for any such commodity is PRICE and what remains to be analyzed is the likely future dynamics of P fertilizer prices in the face of the need to double food production by 2050 while simultaneously satisfying the burgeoning bioenergy industry. “Not quite assured”, indeed.
Is this any way to run a biogeochemical cycle?

Aquatic Dead Zones

      I’ve published several links to global maps of coastal hypoxia. Now, NASA has produced a new map of global hypoxic zones, based on Diaz and Rosenberg’s . Spreading Dead Zones and Consequences for Marine Ecosystems. in Science, 321(5891), 926-929.  NASA’s EOS Image of the Day writes on  Aquatic Dead Zones.

      Red circles on this map show the location and size of many of our planet’s dead zones. Black dots show where dead zones have been observed, but their size is unknown.

      It’s no coincidence that dead zones occur downriver of places where human population density is high (darkest brown). Some of the fertilizer we apply to crops is washed into streams and rivers. Fertilizer-laden runoff triggers explosive planktonic algae growth in coastal areas. The algae die and rain down into deep waters, where their remains are like fertilizer for microbes. The microbes decompose the organic matter, using up the oxygen. Mass killing of fish and other sea life often results.

      Limits to Phosphorus?

      People have more than doubled the global flows of phosphorus, but unlike nitrogen, the other main fertilizer, phosphorus is mined. David A. Vaccari, an engineering professor from Stevens Institute of Technology writes in Scientific American about Phosphorus Famine: The Threat to Our Food Supply:

      Altogether, phosphorus flows now add up to an estimated 37 million metric tons per year. Of that, about 22 million metric tons come from phosphate mining. The earth holds plenty of phosphorus-rich minerals—those considered economically recoverable—but most are not readily available. The International Geological Correlation Program (IGCP) reckoned in 1987 that there might be some 163,000 million metric tons of phosphate rock worldwide, corresponding to more than 13,000 million metric tons of phosphorus, seemingly enough to last nearly a millennium. These estimates, however, include types of rocks, such as high-carbonate minerals, that are impractical as sources because no economical technology exists to extract the phosphorus from them. The tallies also include deposits that are inaccessible because of their depth or location offshore; moreover, they may exist in underdeveloped or environmentally sensitive land or in the presence of high levels of toxic or radioactive contaminants such as cadmium, chromium, arsenic, lead and uranium.

      Estimates of deposits that are economically recoverable with current technology—known as reserves—are at 15,000 million metric tons. That is still enough to last about 90 years at current use rates. Consumption, however, is likely to grow as the population increases and as people in developing countries demand a higher standard of living. Increased meat consumption, in particular, is likely to put more pressure on the land, because animals eat more food than the food they become.

      Phosphorus reserves are also concentrated geographically. Just four countries—the U.S., China, South Africa and Morocco, together with its Western Sahara Territory—hold 83 percent of the world’s reserves and account for two thirds of annual production. Most U.S. phosphate comes from mines in Florida’s Bone Valley, a fossil deposit that formed in the Atlantic Ocean 12 million years ago. According to the U.S. Geological Survey, the nation’s reserves amount to 1,200 million metric tons. The U.S. produces about 30 million metric tons of phosphate rock a year, which should last 40 years, assuming today’s rate of production.

      Already U.S. mines no longer supply enough phosphorus to satisfy the country’s production of fertilizer, much of which is exported. As a result, the U.S. now imports phosphate rock. China has high-quality reserves, but it does not export; most U.S. imports come from Morocco. Even more than with oil, the U.S. and much of the globe may come to depend on a single country for a critical resource.

      Some geologists are skeptical about the existence of a phosphorus crisis and reckon that estimates of resources and their duration are moving targets. The very definition of reserves is dynamic because, when prices increase, deposits that were previously considered too expensive to access reclassify as reserves. Shortages or price swings can stimulate conservation efforts or the development of extraction technologies.

      And mining companies have the incentive to do exploration only once a resource’s lifetime falls below a certain number of decades. But the depletion of old mines spurs more exploration, which expands the known resources. For instance, 20 years ago geologist R. P. Sheldon pointed out that the rate of new resource discovery had been consistent over the 20th century. Sheldon also suggested that tropical regions with deep soils had been inadequately explored: these regions occupy 22 percent of the earth’s land surface but contain only 2 percent of the known phosphorus reserves.

      Yet most of the phosphorus discovery has occurred in just two places: Morocco/Western Sahara and North Carolina. And much of North Carolina’s resources are restricted because they underlie environmentally sensitive areas. Thus, the findings to date are not enough to allay concerns about future supply. Society should therefore face the reality of an impending phosphorus crisis and begin to make a serious effort at conservation.