Urine as Fertilizer?

Collecting Urine—and Attitudes—at Rich Earth Institute

Photo courtesy of Rich Earth Institute

Written By

Tatiana Schreiber

Written on

February 22 , 2017

At the Rich Earth Institute in Brattleboro, staff, board members, and the many local “peecyclers” who contribute to the group’s Urine Nutrient Reclamation Project (UNRP) pepper their conversations with pee-related humor and hold an annual “Piss-off” contest for who can donate the most urine. Beneath the levity, though, the profound need for society to conserve water, protect land from nutrient run-off, and close a broken ecological cycle powers the organization’s efforts to divert urine from the waste stream and make it available as a high-nitrogen fertilizer.

Although human waste was used as fertilizer for many centuries in many parts of the world—and still is in some regions, such as northern Europe—modern sanitation systems have separated us from this potentially powerful resource and reinforced cultural taboos that suggest urine is “dirty.”  Rich Earth aims to re-value urine, which has an N-P-K ratio of about 9:1:2.5—with some variation depending on people’s diets—as well as smaller amounts of calcium, magnesium, sulfur, and micronutrients. The widespread use of urine as fertilizer will require changing regulations that currently do not adequately address this possibility. (Rich Earth has secured a permit for a mobile urine pasteurizing unit, through the Vermont Agency of Natural Resources’ Watershed Management Division, which enables its ongoing research in the field.)

As a member of Rich Earth’s board of directors over the past three years, I helped the organization document the experience of its urine donors, using surveys, interviews, and informal conversations at potluck dinners to better understand the social and cultural issues associated with the nutrient reclamation project. Perhaps the most significant idea that emerged was that while people may have been a bit uncomfortable at first, their attitudes did evolve. The 150 or so people who have volunteered to collect urine at home and bring it to a central depot are clearly “early adopters” of the idea of recycling urine, but their experience suggests that attitudes among others can shift, as well. Over time the Rich Earth peecylers (as they call themselves) became more comfortable collecting urine, more active in water conservation, more willing and able to talk about what they were doing with friends and neighbors, and excited about what they were learning from Rich Earth’s research results.

When asked in a written survey why they were participating, a typical response was to “reduce [the] waste stream, reduce fertilizer run-off and pollution, save water, [and] reduce fossil fuel use.” People often saw their participation as important because they believed it would help lead to improved water quality and soil health. Some also mentioned wanting to learn how to fertilize their gardens using a locally available resource. People were often energized about what they had discovered through the project: “I am so impressed by this simple process that turns a waste product into something so useful, saves water, and avoids chemical fertilizers in our soil. Amazing! I love the environmental education that happens when curious visitors ask about that weird jug in our bathroom. It has started some good conversations!” Of course no “weird jugs” would be needed if simple urine-diverting toilet technology became more widespread, something the Rich Earth Institute strongly advocates.

When asked what they liked most about participating, one person wrote: “It is a relief to be doing something with immediate positive environmental impact.” Another said, “We will always have a lot of urine everywhere. Using it in the growing process for food production seems logical and closes the cycle. It will no longer be ‘waste.’” Contributing to what they see as important research, and following the progress of that research, has encouraged many of the participants to stay involved since Rich Earth’s founding in 2012 by Abe Noe-Hayes of Putney and Kim Nace of Brattleboro. Grants from the USDA, the EPA, the Water, Environment and ReUse Foundation, and most recently, four years of funding from the National Science Foundation (NSF) have enabled Rich Earth to collaborate with the University of Michigan, the University of Buffalo, and other institutions to investigate numerous topics: crop yields; appropriate dilution levels; and the fate of any pharmaceuticals, bacteria, and viruses that may be present in the urine (that is, whether and how they move through soils and into plant tissues).

In experiments so far, yields of urine-fertilized hay have been comparable to chemical fertilizers. The final results from the pharmaceutical studies have not yet been published, but the data indicate that while trace levels of pharmaceuticals could be detected in vegetable tissue, the levels were very low. As Abe Noe-Hayes puts it, “a person would have to eat a salad from the study plot every day for 2000 years to get a single dose of acetaminophen (Tylenol).” The NSF funding includes further research on: what happens to pharmaceuticals, hormones, and other possible contaminants in the urine; processing and treatment methods to reduce any health or environmental risks; and a significant “social research” component that takes off from what has been learned so far.

I’ve now stepped down from the Rich Earth board to work as a research associate on this social research component, helping to discover the attitudes and beliefs that affect whether and how we can make the transition from flushing away our urine to seeing its value as “liquid gold,” as advocates call this nutrient-rich material. With university partners, we will be exploring these questions here in New England and in several other regions around the country during the next four years. Making this transition depends, in part, on farmers’ interest in using urine or a urine-derived fertilizer, as well as developing appropriate regulations.

Farmers weigh in

With regard to farmer interest, two small surveys that Rich Earth conducted among New England farmers show that the great majority of the 61 responses were positive, though cautious. Examples of positive responses included: “I think it is a great way to start closing the nutrient cycle—counting humans as part of the whole environmental web,” and “[This] could be a silver bullet; cost effective, renewable, recycling…” and “I think that basically urine is urine and it does the job” and “It’s about time we started using this valuable nutrient in the field instead of…flushing it down the toilet.”

However, a few people had initially negative responses, such as “skepticism, worry about toxins.” One organic farmer wrote: “This is a very bad idea. Organic production using composted animal inputs is all we need in order to maintain fertility. Human waste contains too many variables to be attractive to the organic producer. Can you guarantee that the humans generating the urine have only ingested organic food? I can guarantee that with the animals on my farm and that of some of my certified organic neighbors.” This suggests an important area for research: Are farmers who currently practice organic or “regenerative” methods more or less open to the possibility of using urine than conventional farmers? There may also be variation in farmer concerns about whether or how the trace levels of pharmaceuticals in the urine affect soil microorganisms.

Some of those surveyed were concerned about how the use of urine would affect their organic certification. Currently there isn’t a clear answer to this question. Organic standards prohibit the use of sewage sludge, but urine that has been collected prior to going to a treatment facility is not “sewage.” This issue has not yet been presented to the National Organic Standards Board (NOSB) and will need to be addressed in the future.

Not surprisingly, many farmers wondered how their customers would respond to the use of urine-derived fertilizers on their crops. The new research will seek to find out what information farmers believe would help customers feel more comfortable with this practice. Urine-based fertilizer could be used on food crops, forage crops, or non-edible crops such as flowers. In the initial surveys, most farmers said they would consider using urine on hay, but fewer were ready to say “yes” to its use on edible crops. The research will differentiate among different edible crops: Might farmers be more open to using these fertilizers on perennials such as fruit and nut trees, rather than on annual crops? One farmer in the earlier surveys, for example, felt that “dry beans, barley, popcorn, winter squash, and other storage crops…would be ideal for this application.”

The new social research will include in-depth interviews and small group conversations with farmers, agricultural educators, the “general public” (that is, people who eat and people who pee), planners, environmental officials, wastewater treatment professionals, and others. The research agenda also includes evaluation of tools and techniques for communicating about this issue: For example, is “peecycling” a useful construct, or is this language off-putting to some?

Although not currently part of the funded research, it would also be useful to gain a clearer understanding of how the nutrients in urine move in soil, how they may behave differently under different growing conditions, and how urine or urine-derived fertilizers interact with soil biota. Learning more about these questions may help clarify how urine can most effectively be applied to keep nutrients out of waterways and on the land where plants can use them. The Rich Earth Institute is eager to hear from potential collaborators who may want to work on these topics.

For more information about Rich Earth Institute, see richearthinstitute.org.


About the Author

Tatiana Schreiber

Tatiana Schreiber

Tatiana Schreiber is a research associate at Rich Earth Institute in Brattleboro, and also consults on complementary plants for growing with solar arrays. She teaches ecological agriculture at local colleges and grows heirloom and unusual garden seedlings including medicinal plants at Sowing Peace Farm in Westminster West.

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