Food Crop Fertilizer Features (Gulp!) Human Urine

It's the ultimate in recycling. Take some wood ashes from the fireplace, add a little of your own urine and spread it around your tomato plants. You may get a blockbuster crop.
Photo: Food Crop Fertilizer Features (Gulp!) Human Urine: New Fertilizer Is Safe for Humans, Scientists Say
Scientists in Finland have found that wood ash and human urine perform just as well as more expensive mineral fertilizers, at least for some crops, such as tomato plants.
Scientists in Finland have found that wood ash and human urine perform just as well as more expensive mineral fertilizers, at least for some crops, while doing less damage to the environment. The combination is rich in nutrients, nitrogen, phosphorus, potassium, calcium and magnesium. The researchers raised a healthy crop of tomatoes in a carefully controlled series of laboratory experiments.

Other research has shown that human urine is an effective substitute for synthetic fertilizers, at least for cucumbers, corn, cabbage, wheat and tomatoes. Ash has also been shown to be useful in agriculture.

But the Fins say they are the first ones to combine urine with wood ash, and plants treated with that substitute performed four times as well as unfertilized plants and left the soil less acidic. The scientists insist it's safe and doesn't pose "any microbial or chemical risks."