Human waste comes out as a resource – as fertilizers – in the end of the cycle when talking about ecological sanitation. EcoSan dry toilets are designed so that urine and faeces are separated into their own containers. Therefore, one can obtain two kinds of fertilizers – one from faeces and the other from urine. Usually, the faeces are composted with sawdust, and the compost can be used to help plants grow. Urine on the other hand must be stored for six months before using to eradicate pathogens. It is relatively common to use compost as fertilizer, urine is still a underused resource. In this blog post, we’ll share some insight on the pros and cons of urine as a fertilizer.
Advantage of Urine: High Quality, Low Cost
In the cover photo of this blog post, the left side of the plantation was fertilized with chicken feces and the right side with urine. As you can see from the photo, urine has done a remarkably better job. What explains this?
Urine contains significant quantities of all the main nutrients that plants require for growth: Nitrogen, Phosphorus, and Potassium. In addition, the amounts are well-balanced and urine is nitrogen-rich. Especially phosphorus appears in a form that is extremely plant-friendly, therefore urine can be described to be a quite efficient fertilizer for plants requiring phosphorus for growth. In a research by Wightman (1999), it is stated that the application of urine had almost three times higher phosphorus content, and that the nitrogen content was also higher that with regular fertilizers.
Furthermore, urine is efficient for controlling various crop pests (cf. Wightman, 1999). Usually, pesticides might cause water pollution and soil contamination. Hence the shift to environment-friendly pesticide is highly encouraged today. As said, urine has potential in this field as well: it can work as a pesticide and soil nutrient replenishment.
Another benefit of urine fertilizer is that it is much cheaper than other fertilizers. In case urine would be sold as fertilizer, the real price would depend on the local prices of fertilizers, although the average value of urine produced by one person per year is at around 4–7 euros.
Disadvantage of Urine: Stigmas and Low Level of Awareness
Although urine is cheap and is considered beneficial as fertilizer, it is not a commonly used in Tanzania. “Would you eat vegetables grown with urine?” was asked from the participants in our two workshops in the informal settlements. Among the participants, there were farmers, users, local authorities, and PU members, and not all answered yes although they are well familiar with the function of EcoSan and the full life-cycle of human waste it provides. The most interesting part was that even some PU members were not convinced about the safety of urine as fertilizer. One issue that was remarked, was that people didn’t like to combine the word “urine” with something that relates to food.
In addition to the attitudes towards urine, the level of knowledge in using urine – how to and why – is extremely low. For example, at one farm that we visited during the field trip, one trial on urine had failed due to bad instructions. Hence, there needs to be some improvements in the sharing of information and knowledge.