Keyhole Gardens

Following a story on BBC News that fellow blogger Sokari of BlackLooks had already picked up earlier in June (as well as Alison), our reader Zeno dropped in an e-mail, asking if we knew more about keyhole gardens.

Keyhole gardens?

Actually, I had heard about those Folkewall installations in Gabarone, Botswana the other day that are used for greywater recycling, but keyhole gardens were indeed quite new to me. Guess this also shows how many smart solutions still exist out there that will need to be rediscovered and put in use.

source: African Gardens

Keyhole gardens are a technique used to grow vegetables in a dry climate. They are actually a special form of raised bed gardens: circular waist high raised beds with a path to the center. Walled in by stones, there’s a basket made from sticks and straw in the center that holds manure and other organic kitchen waste for compost.
Since they look like a keyhole from above, they are often called keyhole gardens and also promoted under this name in Lesotho, where the charity organisation “Send a Cow” has been promoting the creation of these special gardens for some time now.

So what makes these gardens so special?

  • the surrounding stones retain the rich soils and keep it safe from erosion
  • the round shape retains moisture
  • compact size, even small plots can be used for gardening
  • raised beds enable the sick and elderly to help with the gardening work
  • center in the middle is used for composting and reuse of greywater (= reuse of nutrients)

“Send a Cow” also created a very informative website on their activies and published some valuable How-to-manuals for us to adopt this smart approach. Please also check out this funny animation on YouTube which puts it in plain enligsh comic style :-)

Now I am only curious to know if we could also mix the greywater with some collected urine and use that as additional fertilizer. In any case, keyhole gardens are a very appropriate “technology” which certainly isn’t limited to countries with a dry climate.

27 comments » Write a comment

  1. Urine? hmm… food crops? How does one prevent someone who catches an STD, from transmitting that through the food chain?

    Also, how does on get past the “ick” factor?

  2. Daniel – To my knowledge, I am unfamiliar with any STD that is transmitted in urine, much less urine filtered by dirt, time & a plant before eating it. It’s highly possible that they were referring to animal urine and not human urine, but I’m not sure out that. Feces is actually far more toxic than urine (a human will get quite ill, and possibly die, eating feces while they can drink urine just fine). So the filtering process before it gets to the ‘fruit’ should weed out anything that would be bad for the body. The great thing about God’s awesome process!

    As to the ‘ick’ factor: you’re already putting manure on it and people living in these communities rarely need to get past the ‘ick’ factor as their lives are surrounded by these realities in every part of their daily routine already.

  3. Yes that’s a valid question. There actually is a “Guideline for the safe use of wastewater, excreta and greywater” which provides some rules of thumb on the reuse of urine. I did in fact refer to human urine which would of course be stored for some time (at least 1 month) and then be diluted with water to work as a natural fertilizer with a safe timely distance of 4 weeks prior to harvest.
    As for STDs, I think they can not be transmitted through urine (which is very clean btw) and even through the storing process, any additional pathogens will be reduced to a minimum.
    With rising prices for fertilizers and subsidized fertilizer projects as seen in Malawi during the last few years, the reuse of biological nutrients in wastewater is a smart approach to closing the loop, i think.
    For more information on this, especially to a rural African context, pls check out this nice booklet by Peter Morgan. :-)

    @Alison: those posters are cool, thx!

  4. Urine is usually very sterile but bladder infections, and some STDs could be a concern. Maybe it should be diluted first and then stored.

    If a non food crop could be proposed which would provide some benefit (like the plant based pesticides the boy was making) then urine could be used for that and some of the plant waste could be diverted to the food based gardens.

    editor: Well, from a process engineering perspective, I think it makes sense to store liquids first and then have them diluted.

  5. Urine is in fact very sterile – bladder infections and STDs are after appropriate treatment (described by JKE) no problem.

    For me it makes much more sense to use the urine for the food crops – these need the nutrients, the non-food crops only very little.

    It is of high importance to finally overcome the lacking acceptance for using urine, humanure or whatever it’s called – these products are often more hygienic than any sewage and feacal sludge and even chemical fertilizer.

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  8. HEY, be careful!you will give people the wrong idea, the author of this report was asking if they use urine, the report/film said nothing about “blackwater” which is urine and feces, just greywater from washing up and dishwater.

    editor: Yes indeed, the film is just about keyhole gardens and using greywater only.
    The reuse of urine and recreation of fertile topsoil seem to be very appropriate to the situation in Lesotho though – hence this further discussion regarding any additional use of yellow- and brownwater (not blackwater).

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  11. I live in Oklahoma – very hot & dry. I’m making raised beds (we have clay soil)- the keyhole garden sounds doable – advantageous. Thanks.

  12. We put this video together at Send a Cow to inform school pupils in the UK about life in some African countries. It seems like the video and other resources are quite popular outside of this context too. As the UK education (ie UK schoools) manager, I’m not able to comment with knowledge about the grey/yellow/black water topic, but I do know that many farmers are experimenting with some of these methods. For instance, in Uganda I know of a farmer who moves his latrines (not sure if shallow or deep pit?), leaves them for a period of time and then plants bananas, which do very, very well.
    Back to keyhole gardens, they do very well in many locations, especially those with heavy rain as well as dry seasons too, so good for the UK. In East Africa (where they originated at St Judes Organic training centre in Uganda) they look different, as per the fourthway link provided by another poster. So, best to adapt them, although the multi-layered approach seems to work very well. If anyone tries them in other countries, please email education@sendacow.org.uk – many thanks!
    By the way, we also have a video about Bag Gardens and will be making one about Tip-Taps too…

    editor: thx for your comment, John! Those moving shallow pit latrines are btw called Arborloo – see also our post on the VIP).

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  14. Not that it’s important, but how is it a keyhole shape?
    Keyholes are circular with a chunk added onto the bottom, not a chunk taken away.

  15. I think the idea is that the voided space is the keyhole, not where the actual garden is. Like you could insert a key into the garden.

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  17. After going through your perfectly structured and point hitting article, I have decided to share it with my blog readers. Can I have your write-up republished on my website with a link back to your website? I find it educational and also intriguing for my teaming guests and since I don’t have much time and energy to write fresh article regularly, my guests will be kept up to date from your tremendous knowledge.

  18. Hello James,
    I didn’t actually write the post, but the information is all from Send a Cow (I took that photo, and made the video!) and so it’s ok to share from our point of view. The video has moved since the post was made and there is another useful one. Please use either or both of these two links for your blog:

    http://www.youtube.com/watch?v=ykCXfjzfaco&feature=channel_video_title

    http://www.youtube.com/watch?v=2I-_6Bog-rM&feature=relmfu

    It would be great if you could add a link to the homepage on our website too (www.sendacow.org.uk), thank you.

    Best wishes,

    John Cleverley
    Send a Cow

  19. @James: thx for asking!
    @John: thx for the updates – I’ve updated the main video to the new link.

  20. Several family members and I are all building keyhole gardens this year. But we have a question: How do you keep the material (compost) from going down down down over time? We’ve been filling our gardens with both brown and green matter and watering it in as we go, but this material will break down over time and the gardens will shrink considerably. Any suggestions for how to fix this (other than wait for a long time before planting anything in it, which is not a very feasible solution)?

  21. Good to see people are finding this useful. To try and answer some questions:
    Laura – not sure if i understand. You keep adding compost to the central basket and adding in compost and topsoil to the garden over time. Applying green manure will help to keep the soil fertile aswell. But as with any garden, it will take a while to settle.
    Noble – pointers will depend on where you are based. If it’s arid, then a small roof on the compost basket will help, if wet/cold, then cardboard will help insulate the compost. Face the walkway away from the predominant sunshine (eg in the UK face it north) to make the most of available sunlight hours – hope that helps!