Nitrogen, phosphorus, and potassium are among plants' key needs—and your urine contains all of them. That's why Vermont's Rich Earth Institute is studying the use of human urine as fertilizer, Modern Farmer reports. There's already plenty of evidence that it works. Yahoo cites one study, earlier reported by National Geographic, in which a researcher found that a blend of urine and compost resulted in taller sweet pepper plants with more peppers.
A Swedish study, meanwhile, sent urine from housing projects to a farm. Researchers found that one adult's pee provides enough plant nutrients for 50% to 100% of another person's diet, Modern Farmer notes. A farmer working with the Rich Earth Institute also found urine to be highly effective in a 2012 field test, results that helped the group get a $10,000 USDA grant. Last year, the institute collected some 3,000 gallons of pee from 170 people. "When people realize that they produce something every day that can be helpful to the environment and the earth, it’s a very wonderful feeling," says its administrative director. But hurdles remain: For instance, human urine can contain remnants of medications. (Read more urine stories.)