Sustainable Stool Part 3

Written by Sarah Steely

Tuesday, January 22nd 2008

In this installment I discuss historical use of human waste as fertilizer and sustainability aspects of humanure.

China and other Asian countries have been recycling their excrement for thousands of years. While they have not necessarily been composting it, they have been returning it back to the soil as fertilizer. Night soil is the term commonly used to refer to raw sewage spread on fields as fertilizer. As with the application of any raw manure to food crops, there are a couple of safety issues associated with this practice. If the sewage is not composted then there is a risk that pathogens and worms present in the manure come in contact with the crops. Interestingly, it is thought that this is one of the reasons that the Chinese do not generally eat raw foods and peel their fruits and vegetables (Agroecology Research Group 1999). The application of raw sewage to crops can also lead to runoff of nitrogen and phosphorus in very wet areas.

Historical evidence of the composting of human manure is difficult to find, but some sources, including the WHO, declare that in China the composting of human manure “with crop residues has enabled the soil to support high population densities without loss of fertility for more than 4000 years (Jenkins 1999).” Some of these farmers’ families have been working the same plot of land for centuries, so they must be doing something right. Another example of cultures that reuse their excrement are the Hunzas of Pakistan (Jenkins 1999).

As far as the sustainability aspect of humanure, Joseph Jenkins, the author of The Humanure Handbook, eloquently sums it all up in the following excerpt about humanure:

“Thermophilic composting requires no electricity and therefore no coal combustion, no acid rain, no nuclear power plants, no nuclear waste, no petrochemicals, and no consumption of fossil fuels. The composting process produces no waste no pollutants, and no toxic by-products. Thermophilic composting of humanure can be carried out century after century, millennium after millennium, with no stress on our ecosystems, no unnecessary consumption of resources, and no garbage or sludge for our landfills. And all the while it will produce a valuable resource necessary for our survival while preventing the accumulation of dangerous and pathogenic waste. If that doesn’t describe sustainability, nothing does (Jenkins 1999)."

One part of the system that is not necessarily sustainable is the cover material, depending on what kind it is and where it comes from. In order to keep the contents of the toilet from smelling you have to cover the toilet deposits with a good layer of cover material. If sawdust is taken from local lumber production, then it can be sustainable as long as the forestry practice is sustainable.

Now this might be a little extreme and maybe even unrealistic, but consider this: If humanure begins to become more socially acceptable and a market develops, then homes could compost their excrement and sell it as an additional source of money. Farmers in Denmark install wind turbines and sell the electricity while farming the land beneath them, generating a second source of income (Dauncey 2003). Why couldn’t humanure production be like this? People who have time and desire could create humanure and sell it to others who are unable or do not want to actually do it.

Humanure is a sustainable, non-polluting way of recycling our excrement. It does not require electricity, water, or fossil fuels and it can return nutrients that our body does not use back to the soil so that plants can use them. It is easily done by families and small farms. The next step will be to make humanure a more socially acceptable process in developed nations and to convince organic farmers that you cannot get more organic than using your own waste products to enhance plant growth.

Part 1 Part 2

Works Consulted

Agroecology Research Group. 1999. Case Studies: Human Manure; Using Human Manure (“nightsoil”) in the Tai Lake Region of China. Online. Available http://www.agroecology.org/Case%20Studies/nightsoil.html

Dauncey, Guy. 2003. A Sustainable Energy Plan for the US. Earth Island Journal. 18:3. 32-36.

Jenkins, Joseph. 1999. The Humanure Handbook; A Guide To Composting Human Manure. Chelsea Green Publishing, VT.

Last update: April 28, 2008
08:09 am

Published in : Research, Eco Culture