National Geographic
Menu

Human Pee Added to Compost Boosts Crops

Discarded food atop a compost pile at an organic farm.
Discarded food atop a compost pile at an organic farm. Photograph by Hannele Lahti, National Geographic

 

People have been using manure as fertilizer for millennia. But scientists now believe they can turn human urine into liquid gold—as composting material. 

The premise is simple: Pee is rich in nitrogen, which plants desperately need. Commercial fertilizers boost plant growth and yield by providing abundant nitrogen to the plant’s roots.

Of course, commercial fertilizers can harm the environment if they get into lakes and streams. As well, not all farmers in the developing world can afford to buy fertilizer for their crops. Enter pee. (Related: “Human Pee With Ash Is a Natural Fertilizer.“)

Debendra Shrestha, a researcher at Tribhuvan University in Kathmandu, Nepal, noted that Nepalese farmers have been applying human urine to their crops for centuries.

Unlike commercial fertilizers, urine is free and abundantly available. Plus, it doesn’t seem to have any harmful environmental effects. The main question that remained was whether it actually worked: Would plants grow better when their soil was treated with human urine?

Pee Power

To answer this question, Shrestha and colleagues grew sweet peppers (Capsicum annum) in soil that had various combinations of human urine, compost, and urea—the main nitrogen-containing chemical in human urine. The urine was collected from communal toilets in Kathmandu, whereas the compost was sourced from cow manure. (Also see “Urine Battery Turns Pee Into Power.”)

The plants grown in soil that had a combination of human urine and compost grew the tallest, yielded the most peppers, and had the most total fruit weight per plant, according to the study, published recently in the journal Scientia Horticulturae.

The scientists say the pee was so effective because of several factors working together. For instance, the mix of compost and urine decreased the amount of nitrogen lost in the soil while making more carbon available to the plants.

“We need to start moving toward the application of urine in combination with compost,” Shrestha said in an interview with <a ” href=”http://www.scidev.net/en/south-asia/news/crop-thrives-on-urine-compost-mix.html” target=”_blank”>SciDev.Net.

To Pee or Not to Pee?

Still, not everyone is convinced. Other studies in Africa that used a combination of human urine, human manure, and poultry manure found that these substances did not yield more crops than commercial fertilizers did. (See “Human Waste to Revive Haitian Farmland?”)

The use of human urine, noted Surendra Pradhan, a researcher at the International Water Management Institute who is based in Ghana, has major problems, according to SciDev.Net.

For one, although urine is freely available, not all cultures might take to the idea of using it on their crops. What’s more, it needs to be used along with compost for it to be effective, since urine alone doesn’t have enough nutrients to sustain plant growth over several years. (Read more about sustainable agriculture.)

Last, although commercially available fertilizers aren’t free, many governments do subsidize their availability, which may decrease the overall appeal of urine-based fertilizers.

Comments

  1. Kevin Arthun
    United States
    July 14, 6:12 am

    The issue is not simple; beware. What works for one person could be totally different for another. Urinologists have documented about 3100 different substances that have metabolized in the body and been excreted via the kidneys.

    http://www.urinemetabolome.ca/

  2. Cindy
    NJ
    October 22, 2013, 7:32 pm

    After several years of failing to produce the garden I was used to I decided to try urine. To bad I started at the end of the summer when most of my plants had died but not the peppers. I did it the lazy way I took a dipper and took it right from the Toilet, I then mixed it with a lot more water and started to put it on my peppers, It is almost frost and my peppers are growing like I have not seen in a long time I diluted it even more and used it on my house plants and they are going nuts. I still cant admit to my friends I use urine they will think I am sick but what gardener gives away their secrets anyway…

  3. Sandra Watters
    Surrey England
    August 4, 2013, 4:11 am

    Responding to Stella Howells’ comment on ‘ days of old’ , people were NOT vegans, we didn’t rise to the top of the food chain by eating only veg.! We are omnivores and if it stood still long enough we would eat it! Farming only came along later and enabled us to settle in one place. Urine has been used for hundreds of years for one purpose or another and we did well on it..waste not want not.

  4. Arun G C
    Nepal
    May 19, 2013, 11:57 pm

    It may be best alternative

  5. Tim Dunn
    USA
    May 2, 2013, 7:25 pm

    What comes next, the discovery of the wheel?

  6. Raul
    Singapore
    April 25, 2013, 11:01 am

    That’s the mistery of human body. Pee has a lot of Nitrogen needed by the plants similar to fertilizers. Old folks in rural areas already know about this long ago.

  7. bahbcat
    SoCal
    April 20, 2013, 4:09 pm

    Those “commercial fertilizers” are largely cow piss. And wet pies.

    A little Urea on the veggie waste helps it cook faster.

  8. bahbcat
    SoCal
    April 20, 2013, 4:03 pm

    Thos “commercial fertilizers” are largely cow piss. And wet pies.

    A little Urea on the veggie waste helps it cook faster.

  9. Stella H Howell
    uk
    April 14, 2013, 4:59 am

    Every human beings excreta is different.
    We are what we eat (besides other things).
    Medication, drugs, consumption of thrash foods including flesh & blood results in putrefied excreta, this is because ones internal organs are diseased in the stage of cancerous.
    Therefore purchasing compost particularly recycled compost is certainly not a good idea.
    In days of old, people were vegans and used their own household excreta on their own soil.

  10. Tom Jarvis
    Siargao Island Philippines
    April 13, 2013, 8:46 am

    I regularly piss over my plants every night and there is an amazing difference in the growth rate of the ones I piss on and the ones I don’t !
    So don’t just talk to your plants piss on them too :-)

  11. Chudamani Akavaram
    Hyderabad
    April 13, 2013, 12:01 am

    As a child I used to find in the house of my grandfather and other relatives that human waste like urine and faeces was dumped on the garbage depositswhichconsisted mainly of animal and vegeteble wastes was allowed to decay and formed into compost. Earth worms and other insects played a significant role in converting the whole mass into a wonderful manure. Yesteryears’ waste material thus formed into present years’ bonanza for the crops.

  12. homer
    roma,tx
    April 12, 2013, 4:16 am

    Seriously ur barely taking this into consideration???slow ass ppl this is logic

  13. Anna Anchala
    New York, New York
    April 12, 2013, 2:52 am

    Long a practice in the United States. Human urine is used in various ways to enrich soil and grow plants.
    Check out the fun book, Liquid Gold: The Lore and Logic of Using Urine to grow plants. June 21 is “Pee-On-Earth Day.”

  14. Gayath Indika Senarath Pathirana
    SRI LANKA
    April 12, 2013, 1:49 am

    COMPOST IS BEGIN OF THE ORGANIC CULTIVATION.WE HAVE TO HELP FOR FARMERS.
    GAYATH.

  15. karthi
    tamilnadu
    April 11, 2013, 7:04 am

    i like it

  16. Tom Key
    Tustin
    April 10, 2013, 3:41 pm

    What about the high salt content in pee?

    Human and animal “waste products” should not be wasted. Each person has a daily and incredible ability to convert complex products into usable soil.