Clay soil and drainage

Discussion in 'Allotments Discussion' started by Liz, Aug 22, 2014.

  1. Liz

    Liz Gardener

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    Hi all,
    We have an allotment with heavy clay soil. In winter parts of it become waterlogged- the lady next us says there is water running underneath her patch and ours. As we are on a slope the main problem is in the lowest corner.
    As a long term plan we are wondering about methods of dealing with the excess water. We have thought of planting water hungry bushes/tree, particularly willow as this roots so easily. Also an option is a drainage ditch. At the moment we have a small pond at the wettest point of the plot, which we made before we discovered the drainage problems, and we lined it with polythene pond liner.
    Any ideas would be very welcome!
     
  2. Steve R

    Steve R Soil Furtler

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    Dig a trench, line it with fleece or similar and then fill up with stones/gravel from your plot or surrounds, then overlap the fleece on top to seal in the stones. This is a fairly cheap and easy option for drainage as it just costs some work and a little fleece. If you can direct this trench to a soakaway, so much the better and this can be just a bigger and deeper area than the trench, but fleece wrapped stones again. BTW, the fleece just stops the stones area becoming filled up with soil, so it can always drain.

    I have a similar problem on my plot, same conditions my clay plot is on a slope and an old beck or land drainage used to run through it, so in inclement weather my plot floods.

    Because of the terrible floods here in Cockermouth back in 2009, there has been a terrific amount of work done so if in the future floods happen again, farmers land and other properties drain better. Consequently, land drain offcuts are very easily obtained from skips and such. I have a couple and will use them within the fleece lined trenches with added stones to make drainage on my plot this winter.

    Steve...:)
     
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    • Kristen

      Kristen Under gardener

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      I never think that's the best solution as the plant needs to be big before it really drinks enough to make a difference. Willows and the like are happy to be in wet ground ... but sadly that doesn't make them an overnight solution :sad:

      Raised beds will help. they can be "lazy raised beds" - just dig out the paths a spit deep and stack the soil on the beds. 4' wide beds is ideal - max width that can be reached from either side. The "shoulders" will erode back into the paths over a year or two, and need some soil spooning back out periodically, and it is also difficultn to plant the shoulders, so you might have a bit less cropping area [than if you go to the trouble of boarding the raised beds - discarded scaffolders boards - i.e. when the split - do well for that job]

      I think your Ditch idea would be fine too - although raised beds' "lowered paths" would do that job too :)
       
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      • Liz

        Liz Gardener

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        Thanks both- obviously the willow is a long term option, but it would benefit all in the future!
        I had been trying to think of ways to stop a ditch filling with soil gradually- gravel is a great idea. Our ground is very stony and every plot has a stone pile! And I have a big roll of fleece so all I need now is the person to dig- family on holiday at the moment.
        If we dug in some drain pipes as well as the ditch, should the ends be covered in fleece to stop soil leeching in, or would filling with stones/ gravel be OK?
        As far as the lowered paths idea goes, in order to avoid more digging, I think we will raise the bed in the wet corner extra high, which should have the same result, and also enable us to mix some compost or sand in with the clay.
         
      • Steve R

        Steve R Soil Furtler

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        I did not mention the tree idea chiefly because of what it will drink, and that will be in direct competition with your crops in times of dry weather or even drought. Also worth bearing in mind is it's root spread, possibly encroaching into cultivation areas and the tree then using up all the water and nutrients that you want your crops to have. It's difficult to really advise without actually being there, but I would think moving the water away from the plots would be the best, quickest and easiest solution.

        Steve...:)
         
      • Kristen

        Kristen Under gardener

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        A full blown "French drain" would definitely be best - that is:

        Trench
        Perforated plastic pipe (comes on a roll)
        Gravel / stones (enough to fill the trench just until it covers the pipe)
        Backfill with soil

        Needs to flow away at lowest point, or dig a big hole and fill it full of rubble as a soakaway.

        One other point about Willow is that it is deciduous, so the amount it drinks in Winter will not be as much as Summer - which might be back-about-face for how you would best need it to work?

        http://www.pavingexpert.com/drain03.htm
         
        Last edited: Aug 24, 2014
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