Peak Phosphorus

Tasseled out corn crop, northwest Iowa, July 2013.

Tasseled out corn crop, northwest Iowa, July 2013.

Phosphorus (P) is a chemical element and exists almost entirely in the form of phosphate (PO4 3-).

For millennia, geology has allowed phosphate to slowly accumulate in ancient seabed formations in just a few lucky locations around the world. P is essential to all life, including plants—such as agricultural crops. So, without phosphate, the breadbasket of America would be empty.

The Green Revolution, the major mid-20th-century expansion of global food production, relies in large part on fertilizer, to the tune of approximately 20 million metric tons of P in fertilizers applied in 2012 worldwide. Without it, agricultural productivity would have to get by with phosphorus that gets into soil by natural weathering of P from Earth’s rocks, which would only yield about 10 percent of what’s currently used—and would be wholly incapable of supporting our current population, much less the 2 billion to 4 billion additional humans expected for 2050.

Where does all this phosphorus for fertilizer come from? From mining operations focused mostly on ancient P-rich geological deposits that are concentrated in just a handful of countries, with Morocco having the lion’s share—about 75 percent at last report. China, in second place, has only 5.5 percent, and the United States trails in seventh with about 2 percent.

The best opportunity for lowering our demand for mined P is to recover and reuse P from agricultural and human wastes.

Animal manures, food-processing wastes, and human sewage constitute about half of the P on the conveyor belt to the environment. These waste streams offer the most immediate route to recovery and reuse because most of the P is in slurries of organic solids that also contain high amounts of energy. Anaerobic digestion, in which specialized microbes chew up organic matter in the absence of oxygen while producing methane gas, or microbial electrolysis cells, in which bacteria generate an electrical current that leads to hydrogen gas, are excellent means to convert the organic materials into highly valuable energy outputs. These microbial processes release the P as phosphate, which can be captured in clean, concentrated, and convenient forms for reuse in agriculture. Using microorganisms this way would give us three valuable things: renewable energy, concentrated P, and water with most of its pollution removed.

Via Slate.

Advertisements
This entry was posted in Agriculture by Heretic. Bookmark the permalink.

About Heretic

I design video games for a living, write fiction, political theory and poetry for personal amusement, and train regularly in Western European 16th century swordwork. On frequent occasion I have been known to hunt for and explore abandoned graveyards, train tunnels and other interesting places wherever I may find them, but there is absolutely no truth to the rumor that I am preparing to set off a zombie apocalypse. Nothing that will stand up in court, at least. I use paranthesis with distressing frequency, have a deep passion for history, anthropology and sociological theory, and really, really, really hate mayonnaise. But I wash my hands after the writing. Promise.

Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s