Sustainable Phosphorus Initiative
Overview: Phosphorus (P) is a critical nutrient for plant growth, and therefore food production for humans. However, there is an emerging concern that current practices are not sustainable for the long term due to decreasing geologic reserves of P and increasing demand for this nutrient due to population growth, growing affluence, and bioenergy production. There are currently no international organizations, policies, or regulatory frameworks governing global P resources for food security.
P in biology and geology.
- P is a chemical element whose unique properties give it an irreplaceable role in biology: in the structure of DNA, in cell membranes, in energetic metabolism, and in bones.
- The human body contains about 650 grams of phosphorus where it is used to construct teeth, bones, and nucleic acids.
- About 20% of the human skeleton and teeth are made of calcium phosphate, Ca(H2PO4)2.
- P follows a 500‐million year geological cycle from weathering of primary rocks to eventual formation of P‐rich sedimentary rocks on the seabed.
- In natural settings, P is often limiting to plant and algae growth and is recycled and reused by plants, animals, and microbes about 50 times before it flows to the ocean.
- P is reused another 800 times by organisms in the oceans before falling into ocean sediments.
Farmers rely on P for high crop yields.
- The primary source of P for farmers is mined P in commercial fertilizers. In 2008, farmers worldwide applied ~ 17 million tons of mined P on their fields to produce their crops.
- Fertilizers represent about 30% of modern large farm costs and a higher proportion still to small and medium sized farmers, especially to developing world farmers seeking to increase yields.
Concentrated geological reserves of P are limited and exist only in a few countries.
- Five countries control nearly 90% of the P mines globally: Morocco (& Western Sahara), China, South Africa, United States, and Jordan.
- The USA has 12 mines but limited reserves remaining.
- Continental Europe, Scandinavia, Indonesia, and India are totally dependent on P imports.
- The energy cost is increasing for mining, refining, packing, storing, transporting and applying phosphate rock and fertilizers, increasing the cost of commercial fertilizers.
- Across the world, both private interests and governments control P mines.
Increasing concentrations of P in aquatic systems are causing ecological and economic damage.
- Major sources of these excesses include concentrated animal feeding operations, urban sewage and runoff, and agriculture. Non-point sources are particularly difficult to regulate and treat.
- P from these sources contributes to the increasing problems of massive algal blooms that cause oxygen‐free, dead zones in lakes, estuaries, and oceans where nearly all aquatic animals and plants are suffocated.
- The world now has over 400 dead zones that are increasing in size by 10% per decade.
- The EPA reports that, in some states, 80% of the water bodies are so impacted by agricultural nutrient runoff that they are unfit for human recreation.
Is P running out?
- Consumption of P is increasing at about 3% annually.
- Industry data suggest that global “peak P” (akin to “peak oil”) is expected to occur around 2034.
- Many P mines are degrading and deliver lower quality phosphate rock, which necessitates mining yet more rock to produce each ton of fertilizer.
- The price of phosphate rock rose 400% in a recent 14‐month period.
- Agricultural production must double by 2050 to meet increased size of the human population.
- Demand for P is increasing as rising global affluence results in increases in meat consumption.
- Expanding bioenergy enterprises are also raising P demand, as biofuel crops demand large amounts of P fertilizer.
How can we achieve Sustainable P by closing the P cycle in human and agricultural waste streams? To answer this, many open issues must be addressed.
- What is the actual extent of current rock P reserves?
- What are the local, regional, and global challenges and promises (cultural, political, technological, geological, and ecological) associated with P sustainability?
- How much of the changing market for P is due to supply and how much is due to demand? What are potential solutions for each?
- Have any regions or cultures solved or avoided these problems? Could these systems be scaled up? Are they feasible globally?
- Are there ways to increase the use efficiency of P added as fertilizer that would decrease demand and runoff? Can crop plants can be developed that more efficiently obtain P from soil?
- Can P demand can be lowered via diets that are “lower in the food chain” and contain less meat?
- Can we develop a “P-neutral” bioenergy economy?
- To what extent can “waste” P in urine, feces, and agricultural runoff be transformed into a valuable source of fertilizer?
By closing the P cycle we can assure humanity’s long-term food security while also protecting the integrity and diversity of natural ecosystems from the massive degradation resulting from excess nutrient loading.
For more info, visit sustainableP.asu.edu or contact: Jim Elser (email@example.com), Mark Edwards (firstname.lastname@example.org) or Dan Childers (email@example.com)
March 20, 2010