By dumping soil nutrients down the toilet, we increase our need for synthetic chemical fertilizers. Today, pollution from agriculture, caused from siltation (erosion) and nutrient runoff due to excessive or incorrect use of fertilizers,32 is now the "largest diffuse source of water pollution" in our rivers, lakes, and streams.33 Chemical fertilizers provide a quick fix of nitrogen, phosphorous and potassium for impoverished soils. However, it's estimated that 25-85% of chemical nitrogen applied to soil and 15-20% of the phosphorous and potassium are lost to leaching, which pollutes groundwater.34
This pollution shows up in small ponds which become choked with algae as a result of the unnatural influx of nutrients. From 1950 to 1990, the global consumption of artificial fertilizers rose by 1000%, from 14 million tons to 140 million tons.35 In 1997, U.S. farmers used 20 million tons of synthetic fertilizers,36 and half of all manufactured fertilizer ever made has been used just since 1982.37 Nitrate pollution from excessive artificial fertilizer use is now one of the most serious water pollution problems in Europe and North America. Nitrate pollution can cause cancer and even brain damage or death in infants.38 All the while, hundreds of millions of tons of compostable organic materials are generated in the U.S. each year, and either buried in landfills, incinerated, or discharged into the environment as waste.
The squandering of our water resources, and pollution from sewage and synthetic fertilizers, results in part from the belief that humanure and food scraps are waste materials rather than recyclable natural resources. There is, however, an alternative. Humanure can undergo a process of bacterial digestion and then be returned to the soil. This process is usually known as composting. This is the missing link in the human nutrient recycling process.
Raw humanure carries with it a significant potential for danger in the form of disease pathogens. These diseases, such as intestinal parasites, hepatitis, cholera and typhoid are destroyed by composting, either when the retention time is adequate in a low temperature compost pile, or when the composting process generates internal, biological heat, which can kill pathogens in a matter of minutes.
Raw applications of humanure to fields are not hygienically safe and can assist in the spread of various diseases. Americans who have traveled to Asia tell of the "horrible stench" of night soil that wafts through the air when it is applied to fields. For these reasons, it is imperative that humanure always be composted before agricultural application. Proper composting destroys possible pathogens and results in a pleasant-smelling material.
On the other hand, raw night soil applications to fields in Asia do return humanure to the land, thereby recovering a valuable resource which is then used to produce food for humans. Cities in China, South Korea and Japan recycle night soil around their perimeters in greenbelts where vegetables are grown. Shanghai, China, a city with a population of 14.2 million people in 2000,39 produces an exportable surplus of vegetables in this manner.
Humanure can also be used to feed algae which can, in turn, feed fish for aquacultural enterprises. In Calcutta, such an aquaculture system produces 20,000 kilograms of fresh fish daily.40 The city of Tainan, Taiwan, is well known for its fish, which are farmed in over 6,000 hectares of fish farms fertilized by humanure. There, humanure is so valuable that it's sold on the black market.41
Was this article helpful?