Swales: hand digging & recommended size

Discussion in 'Designing, building, making and powering your life' started by alextacy, Jul 17, 2009.

  1. alextacy

    alextacy Junior Member

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    Hi there, its been a very long time since I posted on here... back gardening again though & left the (sh)city behind me for a while :razz:

    Currently working on a village project in Zimbabwe that features PC & I'm looking at the options of putting some swales in as the basis for a system that combines food forest strips on the swale with fields of grain/root/legume crop. The intention over time is to increase the area given to tree crop, but that is later.... now I need to plan the swales.

    Does anyone have experience digging large swales by hand? We have deep granite sands, so no problem with hard soil.

    Secondly, is there a recommended size and frequency for the swales (number of them and depth & width)? The slope is around 5 degrees on a piece of land 150m (down-slope) by 300m (across-slope).

    I was thinking swales ~ 1.5m deep & 3m wide; about 50m apart. Any idea of how long this takes digging by hand & with what size labour force were you using?

    Best,

    Alexis

    www.kufunda.org
     
  2. nate_taylor

    nate_taylor Junior Member

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    Re: Swales: hand digging & recommended size

    Got any contour maps?

    google map link?

    how much rain do you get at once?

    beautiful place !

    [​IMG]
     
  3. gardenlen

    gardenlen Group for banned users

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    Re: Swales: hand digging & recommended size

    g'day alexis,

    wow by hand that is a massive task even if the soil is very arrable, and to me a swale dug 1.5 meter deep with the resulting berm will be equivalent to 3 meters deep, would not need 3 meteres wide 1 meter more than enough, and .5 meter deep with the berm will give 1 meter.

    do you have access to machinery? if so you can use a rip tine on the back of a tractor to rip swale lines along the contours they don't need to be exact as does the copy book swale. for us when we did this method we found it opened up the sub soil for better water penetration and was low impact on the landscape. so along those lines if no machinery available then with manual labour and a long handled shovel just turn up a berm no more than the depth of the shovel blade, be less work than trying to dig a trench.

    with the rips you then plant your trees in the rip line, found that trees grow faster this way. and as you can you create a line of mulch along the tree line and around the trees, so then in time this line becomes the swale but the rip is still there. all with no major impact on the landscape and lots less work. even using lines of mulch or other debris you will create a swale. might also be some advantage installing a copy book swale along the top most contour of the property to capture any storm run off if storm run off is in play.

    think latteraly keep it simple.

    len
     
  4. sweetpea

    sweetpea Junior Member

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    Re: Swales: hand digging & recommended size

    Hi, I'm in the US, and in the 1930s the farmland in the midwest lost its topsoil to terrible drought and winds, and in 1935 President Roosevelt arranged for construction of swales throughout the damaged area. They are still working as they should today. You can see Bill Mollison describing it on YouTube. Seach for permascience, then choose Dryland Permaculture Strategies, Part 1. So any research on the US dustbowl, depression ought to get you some information on swales. Also under the permascience group of videos is a harvesting water video. I am adjusting my growing beds by tilling the paths, which on my hillside are uphill from the planting bed, scooping the soil onto the beds, thus lowering the path, which will catch runoff and slow it down.

    Also search YouTube user permaculture08 there are 3 parts on swales.
     

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