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Human Urine May Represent the Future of Fertilizer

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Modern synthetic fertilizer consists of varying amounts of nitrogen (N), phosphorus (P) and potassium (K), which are added to croplands to replace these depleted nutrients in the soil. There are several problems with this method, one of the primary ones being that these are finite resources.

Nitrogen, for instance, must be captured through a process that requires natural gas. And, unlike nitrogen, phosphorus and potassium cannot be synthesized, and our aggressive large-scale farming methods, which deplete soils of nutrients that then must be replaced, are quickly burning through available phosphorus and potassium stores.

We're now hearing discussions of "peak phosphorus and potassium" in the way we discuss "peak oil," and, according to some, we may soon be facing looming shortages of these two critical fertilizer ingredients.  According to well-known investor Jeremy Grantham, writing for Nature:

"These two elements cannot be made, cannot be substituted, are necessary to grow all life forms, and are mined and depleted. It's a scary set of statements. Former Soviet states and Canada have more than 70 percent of the potash [potassium]. Morocco has 85 percent of all high-grade phosphates [phosphorous]. It is the most important quasi-monopoly in economic history.

What happens when these fertilizers run out is a question I can't get satisfactorily answered and, believe me, I have tried. There seems to be only one conclusion: their use must be drastically reduced in the next 20-40 years or we will begin to starve."

Urine May Represent the Future of Fertilizer

Human urine is naturally rich in nitrogen, potassium, and phosphorus, and with about 30 billion gallons produced every year in the US alone,2 it's certainly in abundant supply. For the average person, a year's worth of urine contains about eight pounds of nitrogen and nearly one pound of phosphorus - that's enough to grow about one year's worth of food!3

I am in complete agreement with this concept and for the last year have been collecting all my urine and putting it in the compost tea that I feed my fruit trees, vegetables, herbs, and aloe. It works wonderfully with biochar, as the nitrogen in the urine helps balance the carbon in the biochar.    

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