September 4, 2009

Urine, wood ash potent fertilizer

Human urine mixed with wood ash makes a potent, inexpensive fertilizer without risk of disease, scientists in Finland have learned.

The mix can be safely substituted for expensive synthetic fertilizers to produce abundant crops, researchers at the University of Kuopio said.

During the winter of 2007-08, researchers Surendra Pradhan and Helvi Heinonen-Tanski collected human urine from several eco-toilets in private homes, storing the urine for six months at 45 degrees Fahrenheit. After testing for microbes and bacteria, the urine was mixed with wood ash taken from a household furnace.

Tomato plants fertilized with urine only produced four times the tomatoes of unfertilized plants and as many tomatoes as plants treated with synthetic fertilizer, Pradhan said.

Tomato plants fertilized with the urine-ash mix produced nearly the same yield as plants fertilized with just urine and reduced the acidity of the soil, Pradhan said.

The results suggest that urine with or without wood ash can be used as a substitute for mineral fertilizer to increase the yields of tomato without posing any microbial or chemical risks, Pradhan said.