Between the drought and the deficit here in Southern California, times are looking increasingly desperate: the funding for the Metropolitan Water District's water-saving appliance rebates has dried up; and since you've been adhering to the Monday/Thursday watering ordinance, your garden may have too. But if you find yourself standing hopelessly before an unyielding tomato plant, or deterred from the investment of a low-flow toilet, know that there is a single answer to both these problems, one humorously befitting the call to desperate measures. Though it might seem a “wee” bit gross, Finnish researchers from the University of Kuopio's Department of Environmental Studies say, if it's yellow, let it mellow — in your back yard.
The article published in the Journal of Agricultural and Food Chemistry suggests that human urine can be used as a substitute for mineral fertilizer on tomatoes, without any risks. Researchers Surendra K. Pradhan, Jarmo K. Holopainen and Helvi Heinonen-Tanski conducted the study on potted tomatoes in a greenhouse, where each separate plant was treated with either mineral fertilizer, urine + ash, urine only, or nothing, as a control. “The urine fertilized plants produced equal amounts of tomato fruits [to] mineral fertilized plants and 4.2 times more fruits than nonfertilized plants,” the study says, with levels of the antioxidant lycopene similar in tomatoes from all fertilization treatments and “no enteric indicator microorganisms were detected in any of them.”
Moreover, in a similar study conducted in 2007, which tested the effect of urine-fertilizer on cabbage, Pradhan reported that insect damage was lower on urine-fertilized plants than on those treated with industrial-fertilizer, and more importantly, that urine leaves no distinct flavor on food products.
Of course, like non-pee pee-based fertilizers, urine-fertilizer is not a substitute for actually watering your tomatoes. It will, however, give them a much needed needed boost, and reduce the number of times you flush your regular-flow toilet. Also, unless you're on steroids, urine-fertilizer is basically organic.