Urine can provide complete nutrition for plants.
The composition and bioavailability of nutrients in urine makes it a complete fertilizer for plants.
Each person, depending on food and beverage intake, releases an estimated 1-1.5 liters of urine each day or about 500 liters each year. On a daily basis, this can fertilize one square meter or, annually, it could fertilize .07-.10 acres per person per year.
If all of one’s urine was captured over the year, it could fertilize enough crops to meet 60-90% of one’s annual food needs.
NUTRIENTS & NUTRIENT VALUES
Urine is 95% water but contains macronutrients including Nitrogen (N), Phosphorus (P), Potassium (K), Sulphur (S), Calcium (Ca) and Magnesium (Mg).
Urine also contains beneficial micronutrients, essential for plant growth, but usually missing in synthetic fertilizers. Micronutrients include Boron, Molybdenum, Iron, Manganese, Zinc, Copper.
The chemical composition of urine depends on many factors. For example, the nitrogen level can increase with the consumption of protein-rich food and decrease with sweating. But as a rule of thumb, a concentration of 3-7 grams of N per litre of urine can be expected (Vinnerås, 2002; Jönsson & Vinnerås, 2004).
Urine can be used fresh or it can be stored in an air tight container.
“Human urine contains a high percentage of ammonia nitrogen, about 80-100% of the total content. As a result, it is quick-acting, and its effect can be compared with fertilizer with a high mineral content rather than fertilizer with a large percentage of organically bound nitrogen, such as solid manure.” (Johansson, 2000)
“During storage, pH raises form around 6 to 9 due to the decomposition of urea into ammonia/ammonium (NH4+/NH3) and hydrocarbonate. This is facilitated by the natural enzyme urease present in the urine.” (Hoeglund 2001).
An example of the chemical composition of fresh urine (literature values) and stored urine (simulation). (Mauer, 2009)
|PARAMETER||FRESH URINE||STORED URINE|
|Total Nitrogen TN (gN/1)||8.83||9.2|
|Ammonium/Ammonia, NH4+/NH3 (gN/1)||0.463||8.1|
|Nitrate and nitrite, NO3 – and NO2– (gN/1)||–||0|
|CSB (g O2/l)||–||10|
|Total phosphorus, PGesamt (g/l)||0.8-2||0.54|
|Potassium, K (g/l)||2.74||2.2|
|Sodium, Na (g/l)||3.45||2.6|
|Magnesium, Mg (g/l)||0.12||0|
|Chloride, Cl (g/l)||4.97||3.8|
|Calcium, Ca (g/l)||0.23||0|
TREATMENT PRIOR TO USE
Urine is typically sterile when it exits the body. As precaution, there are methods to treat the urine to ensure any potential pathogens are eliminated.
The lowest cost and efficient method for eliminating pathogens is the storage of urine in a closed tank or container for 30+ days. The decomposition of urea into ammonia/ammoniumand hydrocarbonate – which is facilitated by the natural enzyme urease – leads to an increased pH value (pH around 9). The higher pH has a sanitizing effect, so that bacteria, parasitic protozoa, viruses and intestinal helminths die off over time. An environment with a high temperature and low dilution with water enhances this effect. (Höglund,2001)
Höglund, C. 2001. Evaluation of microbial health risks associated with the reuse of source separated human urine. PhD thesis, Department of Biotechnology, Royal Institute of Technology, Stockholm, Sweden. ISBN 91-7283-039-5. http://www.lib.kth.se/Sammanfattningar/hoglund010223.pdf
Jönsson, H. & Vinnerås, B. 2004. Adapting the nutrient content of urine and faeces in different countries using FAO and Swedish data. In: Ecosan – Closing the loop. Proceedings of the 2nd International Symposium on Ecological Sanitation, incorporating the 1st IWA specialist group conference on sustainable sanitation, 7th-11th April 2003, Lubeck, Germany. pp 623-626.
Johansson, M. 2000 Urine Separation – Closing the Nutrient Cycle. Final Report of the R&D Project: Source-Separated Human Urine – A Future Source of Fertilizer for Agriculture in the Stockholm Region. Stockholm: Stockholm Vatten, Stockholmshem & HSB National Federation
Maurer, M. (2007) Urine treatment – absolute flexibility, Eawag News, March 2007, results from Novaquatis research project, Dubendorf, Switzerland, http://www2.gtz.de/ Dokumente/oe44/ecosan/en-urine-treatment-absoluteflexibility-2007.
Vinnerås, B. 2002. Possibilities for sustainable nutrient recycling by faecal separation combined with urine diversion. Agraria 353, Acta Universitatis Agriculturae Sueciae, Swedish University of Agricultural Sciences. Uppsala, Sweden.