Soil fertilizer question

Asked February 7, 2020, 5:11 PM EST

Hi there, I have read online that diluted human urine is a good source of nitrogen for the garden. I am aware that there may be concern for pathogens, and this may not be appropriate for food gardens, but is it ok to use on ornamental beds? Thank you!

Multnomah County Oregon

3 Responses

Funny you should ask; over the past months I've been working on an annotated bibliography on human urine in agriculture. :)

I would not hesitate to use urine in ornamental beds, and in fact I intend to use it in vegetable gardens, with the following caveats:
  • Upon leaving the body, human urine is generally acidic, but becomes basic. Diluting (I'm thinking 10 parts water to 1 part urine) should protect soil pH;
  • Urine generally does not contain bacteria as it is voided unless there is kidney/bladder infection - so don't use urine from individuals who are ill;
  • Consider the crop receiving the nitrogen from urine sources - what parts do you eat? Not radishes (often eaten raw...) or other root vegetables. But it should be fine on leafy greens so long as the urine is applied with care and precision so that ALL of the urine is applied to the soil and NONE of it splashes on the leaves - the edible parts.
It's really important to add plenty of water in the dilution - as I said about 10 parts water to 1 part urine. Urine contains plenty of chemical salts, that can damage plant roots or disrupt the plant/soil water relationship.

If applying urine to the vegetable garden has too much "euuuh" factor for you, it can certainly be applied to the compost pile - undiluted. Compost is full of microbial groups, and it is unlike that the amount of urine produced on the household scale would overcome the existing community.

Thanks for asking this interesting question! You have made my evening. :)

ONE LAST THOUGHT: As to how much/how often - Vegetables that develop after a flower (tomatoes, peppers, eggplant, beans, peas, squash ... ) will continue to develop leafy parts if provided with additional nitrogen. Tomatoes, squash and beans are vining plants, and these will continue to develop vines and leaves at the expense of fruit production and maturity. Once these types of vegetables have young fruits, urine application should be diverted to leafy vegetables.

I don't teach soils and composting in the metro MG training sessions, but in those counties where I do teach them, the trainees can assure you that I am not put off by discussions of urine, manures, and household waste products. :)

Thank you for this awesome and encouraging response, Linda! I'm glad you are the one who received my inquiry, and didn't get put off by the idea. I would be so grateful to look at your bibliography when it is complete. I would like to read up on how much and how frequently to apply this fertilizer to my garden.
Thank you again!

Thank you for the additional info about the application schedule, Linda. I appreciate the time you have put into this research, to our benefit. I am especially inspired by capturing resources from the waste-stream.
Thank you,
Kasia