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Rapport2010

Practical Guidance on the Use of Urine in Crop Production

Richert, Anna; Gensch, Robert; Jönsson, Håkan; Stenström, Thor-Axel; Dagerskog, Linus

Sammanfattning

The Practical Guidance on the Use of Urine in Crop Production is directed towards decision makers, professionals and extension workers in the agriculture, water and sanitation, planning and environment sectors, as well as the donor community. The main target group is professionals in the agricultural sector. The text gives practical guidance on the use of urine in crop production as a vital component of sustainable crop production and sanitation systems. It covers key aspects of how to use urine from productive sanitation systems as fertilizer in crop production and also includes guidance on how to initiate activities that will facilitate the introduction of new fertilizers to the agricultural community. The handbook is intended to help in establishing links between researchers in the field of sustainable sanitation and agricultural practionners, as well as endusers interested in implemented sustainable sanitation systems. It is easy to read and informative, with examples from case studies and tips on further reading for those interested. Urine used as a fertilizer can help in the mitigation of poverty and malnutrition, and improve the trade balance of countries importing chemical fertilizers if adopted at large scale. Food security can be increased with a fertilizer that is available free for all, regardless of logistic and economical resources. Safe handling of urine including sanitization before use is a key component of sustainable sanitation as well as sustainable crop production. Consumed plant nutrients leave the human body with excreta, and once the body is fully grown there is a mass balance between consumption and excretion. This has three important implications: *The amount of excreted plant nutrients can be calculated from the food intake, for which data is better and more easily available than for excreta. *If all excreta and biowaste, as well as animal manure and crop residues, is recycled, then the fertility of the arable land can be maintained, as the recycled products contain the same amounts of plant nutrients as were taken up by the crops. *Differences in composition of excreta between different regions reflect differences in the uptake of the consumed crops and thus in the plant nutrient supply needed for maintained crop fertility in the region. Irrespective of the amounts and concentrations of plant nutrients in the excreta, one important fertilizing recommendation is therefore to strive to distribute the excreta fertilizers on an area equal to that used for producing the food. Source separation and safe handling of nutrients from the toilet systems is one way to facilitate the recirculation and use of excreta in crop production. Urine contains most of the macronutrients as well as smaller fractions of the micronutrients excreted by human beings. Nitrogen, phosphorus, potassium and sulphur as well as micronutrients are all found in urine in plant available forms. Urine is a well balanced nitrogen rich fertilizer which can replace and normally gives the same yields as chemical fertilizer in crop production. Table I shows an example of yields from field research in Burkina Faso, where yields of urine-fertilized crops did not differ from mineral fertilized crops. The urine from one person during one year is sufficient to fertilize 300-400 m2 of crop to a level of about 50- 100 kg N/ha. Urine should be handled in closed tanks and containers and should be spread directly onto the soil, not on the plant, in N-doses equivalent to what is recommended for urea and ammonium fertilizers. In the small scale, plastic watering cans are suitable for spreading the urine, while in larger scale, spreaders for animal slurry are suitable. Air contact should be minimized in order to avoid ammonia losses and the urine should be incorporated into the soil as quickly as possible. The economical value of the urine can be calculated by comparing with the price of mineral fertilizer on the local market or by calculating the value of the increased yield of the fertilized crop. In Burkina Faso the value of a 20 l jerrycan of urine can be estimated to 25 US cents. A person produces around 500 litres of urine per year corresponding to ~ 6-7 dollars. Including the nutient value of faeces the annual value reaches approximately 10 $US. However the increased maize yield from using this amount of fertilizer is estimated to 50 $US. Figure I: The yield and size of vegetables improves with urine use. Photo: CREPA, Burkina Faso, Dr Moussa Bonzi An example from Niger shows that the annual amount of plant nutrients in the excreta (urine + faeces) from one family is roughly equal to the quantity in one 50 kg bag of urea and one 50 kg bag of NPK, see figure 2. The majority of these nutrients are in the urine, which is relatively easy to collect. Health risks associated with the use of human urine in plant production are generally low. Source separation of urine is a strong barrier against pathogen transmission since most pathogens are excreted with faecal matter. The amount of faecal cross-contamination is directly related to the health risk in the system for urine use in crop production. Collection systems for urine should be designed to minimize the risk of faecal crosscontamination. Groups that are potentially at risk are mainly collection personnel and field workers, groups that come in direct contact with the excreta. Other categories where risks exist, however diminished, are households, local communities and product consumers. Urine is a high quality fertilizer with low levels of heavy metals. Regarding hormones and pharmaceuticals excreted with urine, the risk of negative effects to plants or human beings is low if urine is spread on agricultural land at levels corresponding to the plants needs. The World Health Organization (WHO) guidelines for safe use of excreta in agriculture (2006) promote a flexible multi-barrier approach for managing the health risks associated with the use of excreta. This concept comprises a series of measures/barriers from ‘toilet to table’. Each of the barriers has a potential to reduce health risks associated with the excreta use and it is recommended by WHO to put in place several of these barriers, if needed, in order to reduce the health risk to an acceptable minimum, see figure 3. Barriers include, for example, storage, crop restrictions, withholding periods and reduced contact, correct handling and cooking of the food crop. The text gives examples of how urine can be handled in a safe way in order to minimize risk of pathogen transmission based on the WHO Guidelines for safe use of excreta in crop production. Institutional aspects are increasingly important as productive sanitation systems become mainstream. A challenge is to integrate use of excreta in existing regulatory frameworks. Initially, the following activities are suggested when productive sanitation systems are implemented: • Identify stakeholders and clarify drivers and restrictions for each one in relation to the implementation of urine use in crop production. • Include and target the farmers in the initial planning. • Organize an arena for feed-back and interaction between stakeholders. • Organize local communities so that there is a structure for implementation and a structure for monitoring. Dissemination and knowledge development on urine as a fertilizer is best gained through local demonstration experiments involving organizations that work with small scale farmers and local communities as well as local research organizations. The new fertilizer should be introduced with the same methodology as when introducing any new fertilizer in the agricultural community. In order to be implementable in a local context there is often an additional need to further translate or adapt the wealth of information given in this text to the respective local site conditions. Part two of the book gives recommendations on how local guidelines can be developed and structured and it summarizes the most important factors that directly or indirectly influence farming activities related to urine use. It is complemented by an example of an existing local guideline from Niger that is annexed to the publication

Nyckelord

Urine; fertilizer; crop

Publicerad i

EcoSanRes Publications Series
2010, nummer: 2010-1ISBN: 978-91-86125-21-9Utgivare: Stockholm Environment Institute

    UKÄ forskningsämne

    Miljö- och naturvårdsvetenskap
    Trädgårdsvetenskap/hortikultur
    Fisk- och akvakulturforskning

    Permanent länk till denna sida (URI)

    https://res.slu.se/id/publ/32417