Application of Stored Urine
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Separately collected, stored urine is a high quality, concentrated source of nutrients that can be applied as a liquid fertilizer in agriculture to replace all or some commercial chemical fertilizer.
The guidelines for safe urine use are based on storage time and temperature (please see WHO guidelines for specific requirements). However, it is generally accepted that if urine is stored for at least 1 month, it will be safe for agricultural application at the household level.
If urine is used for crops that are eaten by those other than the urine producer, it should be stored for 6 months. Urine should not be applied to crops within one month before they are harvested.
From normal, healthy people, urine is virtually free of pathogens. Urine also contains the majority of nutrients that are excreted by the body. Urine varies depending on diet, gender, climate and water intake among other facts, but roughly 80% of nitrogen, 60% of potassium and 55% of phosphorus that is excreted from the body is excreted through urine.
Because of its high acidity and concentration, stored urine should not be applied directly to plants. Rather it can be used:
1) Mixed undiluted into soil before planting;
2) Poured into furrows sufficiently away from plant roots and covered immediately (once or twice during the growing season); and
3) Diluted several times and used frequently (twice weekly) poured around plants.
To calculate the application rate, one can assume that 1m2 of cropland can receive the urine from 1 person per day (1 to 1.5L), per crop harvested (e.g. 400 m2 of cropland per year can be fertilized). A 3:1 mix of water and urine is an effective dilution for vegetables, applied twice weekly, although the amount depends on the soil and the type of vegetables. During the rainy season, urine can also be applied directly into small holes near plants, where it will be diluted naturally.
| Advantages | Disadvantages/limitations |
|---|---|
| - Simple technique for all users. - Low cost. - Low risk of pathogen transmission. - Reduces dependence on costly chemical fertilizers. - May encourage income generation (tree planting.) |
- Large volume compared to artificial fertilizer: urine is heavy and may be difficult to transport. - Smell may be offensive - Labour intensive. - Health precautions needed when applying urine. |
Adequacy
Urine is especially beneficial where crops are lacking nitrogen. Examples of some crops that grow well with urine include: maize, rice, millet, sorghum, wheat, chard, turnip, carrots, kale, cabbage, lettuce, bananas, paw-paw, and oranges.
Urine application is ideal for rural and peri-urban areas where agricultural lands are close to the point of urine collection. Households can use their own urine on their own plot of land. Alternatively, if facilities and infrastructure exist, urine can be collected at a semi-centralized location for distribution and transport to agricultural land. Regardless, the most important aspect is that there is a need for nutrients otherwise, the urine can become a source of pollution and nuisance if dealt with improperly. Recommendations for storage time and application techniques must be fully understood and followed.
Urine should not be applied in areas with high salinity.
Health Aspects/Acceptance
There is a minimal risk of infection, especially with extended storage. Still, urine should be handled carefully and should not be applied to crops less than one month before they are harvested. The risk of disease transmission through handling and using human urine are related mainly to faecal cross-contamination.
Social acceptance may be difficult. Stored urine has a strong smell and some may find it offensive to work with or be near. If urine is diluted, and/or immediately tilled into the earth, the smells can be reduced. The use of urine may be less accepted in urban or peri-urban areas where household gardens are close to houses than in rural areas, where houses and crop lands are separated.
Maintenance
With time, some minerals in urine will precipitate (especially calcium and magnesium phosphates). Any equipment that is used to collect, transport or apply urine (i.e. watering cans with small holes) may become clogged over time. Most deposits can easily be removed with hot water and a bit of acid (vinegar), or in more extreme cases, chipped off manually.
References
- Elizabeth Tilley et.al (2008). Compendium of Sanitation Systems and Technologies (low res version). Department of Water and Sanitation in Development Countries (Sandec) at the Swiss Federal Institute of Aquatic Science and Technology (Eawag). (Provides a full overview of sanitation systems.)
- Austin, A. and Duncker, L. (2002). Urine-diversion. Ecological Sanitation Systems in South Africa. CSIR, Pretoria, South Africa.
- GTZ (2005). Technical data sheets for ecosan components- 01 Urine Diversion. GTZ, Germany. Available: http://www.gtz.de
- Morgan, P. (2007). Toilets that make compost. Stockholm Environment Institute, Stockholm, Sweden. Available: http://www.ecosanres.org
- Morgan, P. (2004). An Ecological Approach to Sanitation in Africa: A Compilation of Experiences. Aquamor, Harare, Zimbabwe. Chapter 10 – The usefulness of urine. Available: http://www.ecosanres.org
- NWP (2006). Smart Sanitation Solutions. Examples of innovative, low-cost technologies for toilets, collection, transportation, treatment and use of sanitation products. Netherlands Water Partnership, The Netherlands. pp 51.
- Schonning, C. and Stenstrom, TA. (2004). Guidelines for the Safe Use of Urine and Faeces in Ecological Sanitation Systems-Report 2004-1. EcosanRes, Stockholm Environment Institute, Stockholm, Sweden. Available: http://www.ecosanres.org
- Winblad, U. and Simpson-Herbert, M. (eds.) (2004). Ecological Sanitation- revised and enlarged edition. Stockholm Environment Institute, Stockholm, Sweden. Available: http://www.ecosanres.org
- WHO (2006). Guidelines for the safe use of wastewater, excreta and greywater – Volume 4: Excreta and greywater use in agriculture. WHO, Geneva. Available: http://www.who.int
