In one year, the average northern European adult produces 116 gal (439.11 l) of urine. Many studies give the average daily nitrogen output for a healthy adult at about 11 grams That figure ranges widely, mostly depending upon diet. The more plant or animal protein the population consumes the more nitrogen it excretes.

Two Swedish university studies report that one northern European adult (who consumes plant and animal proteins) produces enough fertilizer in urine to grow 50 to 100 percent of the food requirement for another adult. We excrete these nitrogen-containing compounds as urea, creatine, ammonia, and a small amount of uric acid. These nutrients could feed a hungry and growing population at a lower cost than producing more expensive chemical fertilizer.

The world needs all the nutrients we are flushing away each day in our urine. Given the far-reaching costs of using manufactured fertilizers, utilizing this valuable and usually sterile resource deserves more consideration. Urine costs nothing to produce (unless you count the plant and animal protein we eat), but it does have storage and transportation costs, as does commercial chemical fertilizer.