The urine one person produces annually contains enough fertilizer to grow nearly a whole year’s supply of food.
Human waste is rich in nitrogen (N), phosphorus (P), potassium (K), and other elements essential to plant growth. Just like animal manure, human waste can be sanitized and transformed into natural, sustainably-produced fertilizer for use on agricultural soils.
Urine contains most of the fertilizer found in human waste, containing 80-85% of the nitrogen and 66% of the phosphorus that we flush away each day. Urine also wins from a public health perspective. The diseases associated with poor sanitation are fecal pathogens, while urine is generally free of pathogens.
Adults produce between 100 and 150 gallons of urine per year, containing about 9 pounds of nitrogen and 0.8 pounds of phosphorus. Used to fertilize grain, this is enough to grow wheat for making a loaf of bread every day of the year.
Farming is impossible without phosphorous, which is essential to all life. The mined rock phosphate used to make fertilizer is a non-renewable resource, and high-quality reserves are gradually and steadily being depleted. (This mineral is the source of synthetic phosphate fertilizer, and also the powdered rock phosphate used in organic agriculture.) But the good news is that urine is rich in phosphorus, and by using urine as a fertilizer this limited resource can be recycled indefinitely to grow new crops. For a more thorough discussion of the phosphorous issue, see this article written by Rich Earth Institute board member Tatiana Schreiber.