Gardening for Good: Waste Not, Want Not

Before you turn the page, give me a second. Yes, this is still “Gardening for Good,” and yes, the topic is urine—ours. But it’s also about how we can rethink the way things have always been done in favor of better alternatives for the long run. The connection is not only a sustainable source of plant fertilizer, but an idea that can help protect our water resources and reduce our reliance on fossil fuels.

Imagine the Possibilities
What if humans could adapt to close that loop? Human waste contains nitrogen (N), phosphorus (P) and potassium (K): the same elements that are listed on any package of store-bought plant fertilizer.

You may be thinking, why reinvent something that isn’t broken? But the cheapest, most available plant fertilizers for home and agricultural use have a high environmental cost. The conventional production of synthetic fertilizers requires large-scale mining for phosphorous, often using strip mining techniques. And intense heat is needed to convert nitrogen into ammonia, a primary constituent of fertilizer, in a process that uses natural gas (a fossil fuel)—and a lot of it. That manufacturing process alone accounts for two percent of global carbon dioxide emissions each year.

Children learning about the circular system of consuming nutrients, excreting nutrients, and reclaiming those nutrients in the form of plant fertilizer. Photo: Rich Earth Institute.

And what if we could bypass, or largely reduce, the use of our rivers and streams as tertiary wastewater treatment facilities—which the Connecticut River and its many tributaries are currently being asked to do? If we could subtract human urine in the waste stream at its source, that could potentially eliminate 75 percent of the nitrogen and 55 percent of the phosphorus from municipal wastewater without making any changes to treatment plants, according to a 2022 article in the journal Nature. The overabundance of those nutrients (among other things) can and do result in harmful, sometimes toxic, coastal algal blooms and oxygen deserts in the bottom of Long Island Sound that impact marine fisheries.

Using water to transport and treat our waste also puts pressure on a very limited natural resource: our potable, drinkable, swimmable fresh water. Natural fresh water is mostly locked up in ice and in the ground. What remains accessible—clean surface water—makes up only one percent of the Earth’s total water resource. Diverting liquid human waste from the waste stream (sometimes called pee-cycling) could be the beginning of that game-changer.

An Unexpected Alternative
Enter the Rich Earth Institute, an innovative organization that believes “waste isn’t waste until you waste it.” Conceived in 2011, this small, forward-thinking nonprofit is based in Vermont, although they are thinking and interacting globally. Rich Earth Institute has operated the nation’s first community-scale human urine recycling program since 2012.

Specifically, Rich Earth works to implement systems for recycling nutrients from human waste to demonstrate the potential for reducing pollution, reducing use of petroleum-based fertilizer, and conserving potable water. Although their goal is recycling of all human waste (or, circular sanitation systems), initially their focus is on collecting the liquid, pasteurizing it, and working with farmers to apply the product on their hayfields. For example, currently in southern Vermont 260+ donors generate 13,000 gallons of nitrogen-rich fertilizer over the growing season for local partnering farmers.

The organization’s research arm has spun off Brightwater Tools, a pioneering company that focuses on advanced human waste treatment technologies. Through ongoing research, collaboration, and education, Rich Earth is boldly going where no one else would even consider: making our urine not only useful, but better for the planet, and even ultimately profitable.

Not a New Idea
It turns out that recycling urine is not a new idea, and there are a number of countries that are currently working on this “alternative” concept. Urine was a commodity in the Roman era, where taxes were levied on its collection and trade. Once reduced to ammonia, it was used for many things, from cleaning teeth to dying clothes and tanning leather. During the American Civil War, it was used to make gunpowder. It wasn’t until the late 19th and early 20th centuries that the English implemented centralized sewage management, a model that spread worldwide.

The remains of a bronze-lined tub from a dye factory in Pompeii, Italy. Urine was used as an alkaline agent to help fix colors, particularly indigo, and help achieve vibrant colors. Photo: Gary Robbins.

Rich Earth is among other organizations in Australia, Switzerland, Ethiopia, South Africa, and France who are looking at the possibilities for re-circulating this ubiquitous natural resource. In Sweden, the circular loop potential is already underway, where one farmer is using urine-based fertilizer on his barley crop that will go to a local brewery to make ale.

Challenges Remain
You are right to be thinking that this will not be a quick or effortless transition. Because urine contains so much water, addressing transportation and storage are being researched: Cornell University, for example, is looking at ways to bind urine nutrients to biochar (a kind of charcoal), that could be directly added to the soil.

The amount of nitrogen fertilizer used in agriculture in the United States has climbed to more than eight times what it was 60 years ago. And the EPA estimates that 27 percent of daily average water use is to flush toilets, with four out of five of those flushes just for urine. That adds up to a staggering 1.2 trillion gallons of water flushed every year, all of it containing nutrients that could be diverted or reclaimed and put to good use. Research from Sweden estimates that one quarter of current nitrogen and phosphorus fertilizers worldwide could be produced from human urine.

Opportunities
I have been thinking lately that my enjoyment of nature was a lot easier when I was younger; everything in the out-of-doors was amazing before I knew about, say, invasive species. And now, every time I flush, especially those four out of five, I’ve been thinking about all that nutrient-laden resource that’s being wasted—flushed (after resource-intensive treatment) into our rivers and the Sound. A missed opportunity to recapture some significant benefits.

Adding fertilizer to a field. Photo: Rich Earth Institute.

How we garden—the decisions we make locally about what to plant, how to manage what we plant, and especially the resources that we import and ultimately export to accomplish that—matters. As discouraging at it seems at times, awareness and intent are all part of the continuum of opportunity to make a difference. You know, pee the change you want to see in the world.

Judy Preston is a local ecologist active in the Connecticut River estuary.