In what might be the ultimate pursuit of the perfect vegetable, researchers at Finland's University of Kuopio have discovered that a mixture of human urine and wood ash has the same benefit for tomato plants as traditional fertilizers, producing 4.2 times more fruit than non-fertilized plants. While the wood ash helps reduce the acidity of soils, tomatoes grown just using urine as the fertilizer did just as well as synthetic fertilizers.

"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," said the study, which appears in the current issue of the Journal of Agricultural and Food Chemistry.

The findings from the study have "important implications," the scientists said, because "they may contribute to the development of positive attitudes about the use of urine and ash as fertilizer as a way to both increase crop yield and reduce water pollution." 

Jim Dawson reports for Inside Science News Service, which is supported by the American Institute of Physics.