Can human urine replace chemical fertilisers?

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Vermont TakingThe...
In 2012, Kim Nace, Rich Earth's administrative director, and her partner Abe Noe-Hays, collected 600 gallons of urine from friends and neighbours. The next year, the organisation brought in about 3,000 gallons from 170 human volunteers. Rebecca Rueter, a board member for Rich Earth, also invited members of the local women's chorus to donate their pee.

Rich Earth hopes to double that amount this year to a round 6,000 gallons - enough to fill a third of an average American swimming pool.

"We've given volunteers a few things to make it easier - some funnel devices and things like that," says Kim.

Vermont Tank
The project aims to test human urine as a replacement for chemical fertilisers. Urine contains essential plant nutrients nitrogen, phosphorus and potassium. In collecting human urine, Rich Earth is diverting the same chemicals from waterways to farms, making a potentially harmful substance a boon to crop growth and production.

The urine collection scheme has had some unintended consequences for Kim's home in Brattleboro, which hosts the so-called "urine depot." There is a buzz of conversation as volunteers drop off 5-gallon jugs to be loaded into larger holding tanks. "When people realise that they produce something every day that can be helpful to the environment and the earth, it's a very wonderful feeling," says Kim.

Jay Bailey, who owns and operates Fair Wind Farms with his wife Janet Bailey, volunteered a few hay fields for the initial stages of the project in 2012. He spread a urine solution from the Brattleboro volunteers over the crops from a horse-drawn applicator and, come harvest time, observed that the urine-treated fields were twice as productive as unfertilised controls. The success earned Rich Earth a $10,000 SARE grant from the USDA to expand the trials at Fair Wind in 2013. This year, urine will go to three farms for collaborative trials.

Rich Earth acknowledges that the biggest hurdle to their work is public perception of lingering buckets of pee, or the so-called "ick factor." Urine is actually sterile when it exits the body, save for rare cases of a bladder infection or salmonella poising. Rich Earth has, nevertheless, developed two strategies for eliminating the risk of pathogens, either by solar pasteurisation or long-term storage in a warm greenhouse. Both have proven effective.

A real concern for Rich Earth is left over pharmaceuticals that end up in urine. The EPA has selected Rich Earth for funding to conduct a study of traces of drugs in urine with the help of the University of Michigan.

But, even if there is minimal risk to personal or public health, Kim Nace realises that only a chosen few will ever be willing to collect their own urine with jugs and funnels. A much more realistic option is urine-diverting toilets, which have already been reliably engineered in Sweden.

Kim keeps one in her home, where it's become something of a tourist attraction for people coming to learn about the project. (She welcomes everyone to use her bathroom, but appreciates a donation in return.) The toilet has a division three-quarters of the way toward the front of the bowl. Urine goes in the front, where it's piped to a holding tank; all other waste and toilet paper falls to the back for composting.

The only complaint on the toilet is that the men have to sit to use it. Then again, the requirement keeps Kim's bathroom clean.

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