How Human Urine Can Replace Chemical Fertilizer

January 22, 2018 at 7:34 pm

Farmers are using human urine as a natural, sustainable alternative to fossil-fuel-based fertilizers

Horse drawn urine applicator at Fairwinds hay farm in Vermont.

“Bring us your liquid gold,” the founders of Rich Earth Institute beckon their neighbors on their website.

The organization has collected at least 10,000 gallons of urine since 2012 and donated it to three local farms in Vermont.

Fairwinds Farm, Wild Carrot farm, and Whetstone Valley Farm are part of a grand experiment to see whether urine can replace synthetic fertilizer on a mass scale.

So far, the experiment is a wild success, with farmers on a waiting list to receive donations and hay fields growing greener than ever:

Fairwinds farm hay field. The greener strips have been fertilized with urine.

Urine contains nitrogen, phosphorus and potassium — NPK — essential plant nutrients that are typically mined from the earth (as byproducts of oil and natural gas) and made into fertilizer to replace what agriculture strips from the soil.

“The urine one person produces annually contains enough fertilizer to grow nearly a whole year’s supply of food,” Rich Earth founders Kim Nace and Abraham Noe-Hays claim.

Adults produce between 100 and 150 gallons of urine per year, containing about 9 pounds of nitrogen, 2 pounds of potassium and a pound of phosphorus. This is enough to grow grain for a loaf of bread every day of the year, according to Rich Earth’s research.

Farming is impossible without large amounts of these three minerals, Rich Earth says, and because modern practices strip them from the soil, they must be replaced.

The way they are currently being replaced is entirely unsustainable.

The nitrogen used in commercial fertilizers is synthesized in a process fueled by natural gas, a fossil fuel, which now is increasingly derived using the controversial practice of fracking.

The phosphorus comes from the mined rock phosphate, a non-renewable resource. High-quality reserves are gradually and steadily being depleted. Rich Earth says along with “peak oil,” we’re now entering a period of “peak phosphorus.”

The potash that’s being mined for potassium is also a non-renewable, depleting resource.

So why not do what humans and other animals have done for millions of years — recycle the nutrients from our waste back into the soil? Not only does the practice replenish the soil, it keeps the nutrients out of waterways, where they don’t belong.

Urine typically passes through wastewater treatment plants into rivers, lakes, and bays. In the aquatic environment, excess nutrients (particularly nitrogen and phosphorus) can cause destructive algae blooms that eliminate oxygen from the water.

“This kills fish and other aquatic creatures, causes foul odors that make recreation impossible, and renders the water unfit for human consumption,” it says on Rich Earth’s website.

“In the Northeast,  this is a major problem in areas including Cape Cod, the Great Bay, and Long Island Sound, where nutrient loading regularly creates dead zones and severely damages aquatic ecosystems.”

Rich Earth recently received an $800,000 grant from the National Science Foundation to further test the practicality of using urine to fertilize crops on a larger scale.

The institute is also interested in using human fecal matter — aka humanure — to fertilize crops, but that will require much more work, as it is more likely to contain pathogens. Urine from healthy humans is sterile.

For information on how to fertilize your own garden with urine, Rare Earth has some recommended reading: Liquid Gold: The Lore and Logic of Using Urine to Grow Plants