Pee on Your Peas!


Did you know that the average human produces 511 litres of urine in one year? Imagine if you could actually use this amount of liquid for a good purpose instead of simply flushing it away.. Well good news, actually you can! Not only will this be helping to preserve the energy and water needed to flush and dispose of your urine, you will also be getting a powerful plant fertiliser to boot! While modern society perceives urine as something disgusting to be disposed of as fast as possible, urine is actually pretty useful. Being rich in nitrogen, phosphorous and potassium, it has many key ingredients needed for any healthy garden, in fact many studies show it is much more effective than many commercial and industrial fertilisers you can buy over the counter.

In a recent experiment in Finland, the Heinonen-Tanski group of scientists grew 2 categories of beetroot – one fertilized with urine and the other with ‘traditional’ fertilisers. The ones fertilised with urine were found to be between 10% and 27% larger by mass!  Oh, and of course - the urine was free!

This exercise will challenge our perspective on this valuable natural resource. It can be done individually or be offered to a group of youth where each participant does it individually and shares the impressions.

Activity Type

Experiential - Group/individual


As long as you enjoy!

Learning Outcomes

  • To learn how to use urine as a fertiliser


Step-by-Step Instructions:

  1. Plant or purchase two identical potted plants, they should be suitable for indoor (house or greenhouse) growing.

  2. Label them clearly, one will be fed just water the other with a 10-20% urine / water mix.

  3. Mark a jar clearly for collecting your urine, you don’t want a friend accidentally drinking from it!

  4. Do some research on the correct amount of watering your plants will need, remember to use fresh urine each time they need it.

  5. While urine is safe (unless you have some specific infections etc) it is still advised not to just sprinkle it all over the plant, especially any areas you plan on eating..  It is usually a good idea to pour it gently straight onto the soil/roots.

  6. Keep a record of the plant growth, taking pictures and noting down height, amount of fruit etc or other interesting things at regular intervals.

  7. Make something tasty with what you have grown!



  • Did you observe how things that we consider as waste nowadays can be beneficial?

  • What do you think about the paradigm where we are taught to flush valuable drinking water into the toilets and then spend energy for wastewater treatment?

  • Are there any ways to use these sources smarter?  

Instructions for Submission

Upload a picture of the two pots after a few weeks and submit a short summary of what you noticed. Instructions on how to upload photos and how to submit things in Moodle can be found here: Instructions on Submission&Uploading

Instructions for Assessment

Provide feedback to at least one participant that has done this activity. Instructions on providing feedback can be found here: Instructions on Feedback

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