Are you peeing on your compost pile? If not, you may want to start.
Human urine is rich in the nitrogen that plants need to thrive. The commercial chemical fertilizers widely used to add nitrogen to the soil come at a steep cost to our environment and our health. Their application results in algal blooms, oceanic dead zones, contaminated drinking water, human health problems and more. Meanwhile, we are literally flushing billions of tons of free, naturally-created nitrogen down the toilet each year.
I first learned about this idea from permaculture and edible forest expert, Dave Jacke, when I had the good fortune to walk the land with him this spring at the new Thorn Preserve, a beautiful, 60-acre parcel in the Hudson Valley.
According to Dave, peeing on your compost is a wonderful, completely free, environmentally-friendly way to add essential minerals like nitrogen back to your soil.
I did a bit of digging and found several studies that support Dave’s claim. A field study done in Kathmandu, Nepal found that sweet peppers fertilized with human urine and compost yielded the most fruits and tallest plants of the eight treatments they tried.
Another study done by the University of Kuopio in Finland found that greenhouse tomatoes fertilized with a mixture of human urine and ash yielded nearly four times more tomatoes than non-fertilized plants. The tomatoes fertilized with urine, alone, actually yielded a bit more but the plants did not grow as tall or strong and the tomatoes contained less magnesium than those fertilized with both ash and urine.
According to the researchers, one person could provide enough pee to fertilize roughly 6,300 tomato plants a year, yielding 2.4 tons of tomatoes. That’s a lot of tomatoes…
Although this idea may be new to many of us, it’s actually a pretty old one. Nepalese farmers have been applying urine to their crops for centuries. And “night soil” (a.k.a. human manure) served as a traditional fertilizer in Japan and China right up until World War II in Japan and the 1960s in China. But I would not recommend using “humanure” — in addition to the very considerable ick factor, there are far too many pathogen and heavy metal-related pitfalls to make it safe or practical for home usage.
Some have raised concerns about hormonal or pharmaceutical residues in human urine but, ideally, your compost should get hot enough to burn off any potentially harmful residue in your urine. It’s this same magic of composting that allows commercially-run composting facilities to transform all sorts of waste, including meat scraps, bones, cardboard, waxed paper, grass clippings from lawns that may contain both insecticides and weed killers into rich dirt that even an organically-certified farm can use. And use it, they do.
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