Origins

A little over a year ago, I was giving a presentation about composting toilets at the Common Ground Country Fair. I mentioned the remarkable fact that the amount of manure a person produces over the course of a year contains enough fertilizer to grow a year's worth of food for that person. One gentleman, who owned a composting toilet, stood up and told me he thought I was full of it, and that there couldn't possibly be that much fertilizer in human manure.

I replied with several reasons it had to be so--most notably that since elements can't be destroyed, every gram of nitrogen, phosphorous, and potassium that we eat in the form of food will exit our bodies as manure. The food is digested, and the molecules are rearranged, but the elements are all still there in the same quantity. If we treat that manure to destroy germs and then return it to the soil, we return to the farm all the plant nutrients we took away when we harvested the food.

A farm loses nutrients when food leaves the farm, and in order to keep the soil from becoming impoverished, the farmer needs to bring nutrients back onto the farm to replace what is lost. These nutrients most often come in the form of chemical fertilizer or animal manure from another farm. Though the equation is not precise, generally speaking we can say that the amount of nutrients being added to the farm as fertilizer needs to equal the amount of nutrients leaving the farm in the harvested food. Otherwise, the amount of nutrients that are available in the soil to feed growing plants will steadily decline and yield will drop.

If we can return to farms, in the form of treated human manure, all the nutrients we take from the farms, in the form of food, then we can potentially eliminate the need for chemical fertilizers. This would be a huge step toward sustainability!

The numbers add up, and the theory is there to say it would work, but the man arguing with me was not convinced. I realized that nothing I could say to him was going to change his mind, and that he would not believe me unless I could show him the manure pile, the plot of ground, and the harvested food.

But that is as it should be. The world has seen too many ideas that look great on paper or in the lab, but which fizzle when they brush up against reality. If this human manure business was really such a good idea, where could a person see it in action? Where could we see a person-year of manure supplying the fertility to grow a person-year of food?

There are loads of "humanure" evangelists in the United States, growing vegetables from composted human manure, but it is usually a garden patch, not a farm, and almost nobody keeps records of inputs and outputs. China has a 4,000-year history of depending on human manure as a primary fertilizer, and at least one wonderful book delves deeply into the nutrient balances involved, but it's too far away for most folks to visit.

What we needed was a place right here, where the whole cycle happened in one place: eating, excreting, composting, fertilizing, growing crops, harvesting food, and eating once again. If all this could happen in a well-documented manner, with testing to keep track of the quantities of nutrients all along the way, we could show clearly whether recycled human manure could in fact replace chemical fertilizers as the the primary source of fertility in modern agriculture. If we did it publicly and transparently, we could win over not just to the skeptical gentleman at the fair, but also regulators, agronomists, reporters, politicians, students, farmers, doctors, chefs, and conservationists.

Thus was born the Poopstitute.