The Facts about Phosphate Rock… Are We Running Out?

Most of the phosphate rock that is mined from the earth goes towards making fertilizer for

Phosphorus is a major component of bones and teeth

crop production.  Every cell in plants and animals requires phosphorus to sustain itself and there is no substitute for it in nature.

During the past five years, there were several well-publicized reports suggesting the world phosphate rock supply was rapidly dwindling.  In response, there was widespread concern about whether we were reaching our “peak” supply of phosphate rock and if fertilizer shortages are on the horizon.

Map of world phosphorus resources (IFDC)

Recently updated estimates report that the earth has at least 300 years of years of known phosphate rock reserves (recoverable with current technology) and 1400 years of phosphate rock resources (phosphate rock that may be produced at some time in the future).  These numbers fluctuate somewhat since companies do not intensively explore resources that will only be mined far in the future.

Phosphate fertilizer can be a significant cost for crop production and an important mineral for animals.  However from a global perspective, phosphate is considered as a low-price commodity.  One recent publication estimated that each person consumes an equivalent of 67 lb phosphate rock each year.  This results in an annual consumption of about 9 lb phosphorus per person (or 0.4 oz. daily consumption), which is equivalent to 1.7 cents per day.  

Generalized sedimentary  deposit

Phosphorus atoms do not disappear in a chemical sense, but they can be diluted in soil or water to the point where it is not economical to recover.  Annual phosphorus losses by erosion, manure, and human excrement to the sea roughly balance the phosphorus that is mined, showing that there is substantial room for improvement in efficiency.   Implementing appropriate recovery and recycling of phosphorus from animal manure, crop residue, food waste, and human excreta would make a major step in this direction. 

Efforts to improve phosphorus efficiency and building to the appropriate soil P concentrations  serves to enhance its use.  In developed countries with a history of adequate phosphorus fertilization, the need for high application rates diminishes over time.  This contrasts with the situation in many developing countries where low soil P concentrations still require significant fertilizer inputs to overcome crop deficiencies.

 

Rock phosphate mining in Florida

Members of the public are encouraged to engage in debate over important issues, but there is a danger that oversimplification leads to incorrect conclusions.  The case of looming P scarcity is an example where insufficient information lead to a wrong conclusion.  The wrong notion still persists that there is an impending shortage phosphorus and that limited fertilizer availability will soon lead to global food insecurity.

There may be a scarcity of many earth minerals some day, but the phosphorus supply will not be a concern for hundreds of years.   However responsible stewardship of rock phosphate resources requires a close examination of improving efficiency throughout the entire process, including mining, fertilizing crops, and implementing strategic waste recovery.

Rock phosphate mining in North Carolina