Seems as if the recent "dialog" about pee in the garden has scientific
merit, despite the qualms of the squemish and .... whatever.
Second article of research follows this one.
Wow, I gotta go take a ... you know.
Check out the article for active links...
Gardeners, take note: the secret to growing hearty tomatoes is
remarkably close at hand. Look no further than your fireplace and, er,
According to a study from a group of environmental scientists at the
University of Kuopio in Finland, human urine and wood ash make a
reasonably potent tomato fertilizer, boosting plant growth and fruit
yield dramatically over untreated plants and nearly keeping pace with
conventional fertilizer. The research appears in the August 26 Journal
of Agricultural and Food Chemistry.
The idea did not come completely out of left field—urine and ash have
individually found use in helping plants grow, and their beneficial
aspects appear complementary on paper. A commonly used nitrogenous
fertilizer called urea is prevalent in urine, and wood ash (the
Finnish group used birch) is rich in nutrients, such as potassium and
calcium, that urine lacks.
In the greenhouse test, urine alone actually produced more tomatoes
than urine with ash did—and neither treatment produced quite as much
as did the researchers' mineral fertilizer. But both urine-based
fertilizers roughly quadrupled fruit production when compared to
unfertilized control plants. The researchers estimate that the product
of a single individual's micturition could fertilize 6,300 tomato
plants a year, yielding more than two tons of fruit.
The addition of ash did confer some benefits—those plants were larger
and grew fruit with significantly higher magnesium and potassium
content. A panel of 20 taste testers rated all growing methods as
Some caveats, remain, of course. The urine in the Finnish study was
stored in cool conditions for six months before use, and it is unclear
what effects this had on its fertilizing properties. What is more,
plants are often highly salt-averse, and it seems reasonable to think
that the salinity of urine could be harmful at high enough doses.
Then there's the inevitable gross-out factor: The researchers caution
that even though urine is usually free of the harmful microbes found
in fecal matter, care should be taken to avoid direct contact between
urine-based fertilizer and the plants themselves to prevent
Also: see page for full reference
Stored Human Urine Supplemented with Wood Ash as Fertilizer in Tomato
(Solanum lycopersicum) Cultivation and Its Impacts on Fruit Yield and
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Surendra K. Pradhan*, Jarmo K. Holopainen and Helvi Heinonen-Tanski
Department of Environmental Science, University of Kuopio, P.O. Box
1627, FI-70211 Kuopio, Finland
J. Agric. Food Chem., 2009, 57 (16), pp 7612–7617
Publication Date (Web): August 3, 2009
Copyright © 2009 American Chemical Society
*Corresponding author (e-mail firstname.lastname@example.org; telephone +358
403553169; fax +358 17 163191).
This study evaluates the use of human urine and wood ash as
fertilizers for tomato cultivation in a greenhouse. Tomatoes were
cultivated in pots and treated with 135 kg of N/ha applied as mineral
fertilizer, urine + ash, urine only, and control (no fertilization).
The urine fertilized plants produced equal amounts of tomato fruits as
mineral fertilized plants and 4.2 times more fruits than nonfertilized
plants. The levels of lycopene were similar in tomato fruits from all
fertilization treatments, but the amount of soluble sugars was lower
and Cl- was higher in urine + ash fertilized tomato fruits. The
?-carotene content was greater and the NO3- content was lower in urine
fertilized tomato fruits. No enteric indicator microorganisms were
detected in any tomato fruits. The results suggest that urine
with/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.