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Settle the debate: Adding sand to clay soils.  RSS feed

 
Ben Bishop
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Ok, so one side says if you have clay soils, adding sand will improve drainage. The other side says that it's a great recipe for concrete. Most permies I talk to are the latter (including Dave Jacke and Eric Toensmeier) . But at an Earthworks course I went to there was a soil geologist who said that the claim was ridiculous and that adding sand to clay soils is fine.

Have any of you actually done it or seen it done with success?
 
Adam Klaus
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I'll play. Yes, I have added sand to a heavy clay soil that is high in organic matter. Here is what I have found, after observing it for about four years since applying the sand.

I added a small amount, like maybe a 3/4 inch thick layer, that then got dug in and incorporated. This bed is in my permanent greenhouse.

At first, the sand seemed great, like for the first month. Then, it seemed like it created concrete, like for the next year or so. But then, after it all worked its way in completely, I think it is a big improvement. The soil is much crumblier. The sand particles are quite disguised now, and you wouldnt hardly be able to tell that I ever added the sand.

So yes, in moderation, I think that adding sand in has improved the texture of my soil. The results take time, IME. But having seen the experiment, I would cautiously do it again.

good luck!
 
John Saltveit
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I have added sand to clay and ended up with concrete. I vowed that I wouldn't do it again. As always, I find Adam's observations interesting and thought provoking. So now I say, maybe some day.

I do add gravel to clay, which makes much more sense to me. I have really been impressed with the results of adding gravel to clay. I have had to move trees after having planted them this way, and the soil is quite impressive.

Of course, I add organic material to clay, which helps it over time.
John S
PDX OR
 
Matu Collins
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Location: Southern New England, seaside, avg yearly rainfall 41.91 in, zone 6b
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Ah, since everything depends in permaculture we don't need to settle debates! We just share our experiences and ask more questions.

Adding some sand along with a lot of organic matter would be my plan. I have one experimental bed that I did this with. It drains too well for most crops but it's a good place for plants that don't want wet feet.

My soil is not a clay soil but if it were I'd add a bunch of compost and leaf mould mixed with water and some sand, then mix that in and put mulch on top.

I also would do some in ground hugelkultur, digging a trench, dropping some punky wood in there then putting the above mix on top.
 
Karen Walk
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Location: VT, USA Zone 4/5
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I wonder if you could do all sorts of "illegal" things all at once - mix sand, clay and wood chips all together - and then let it sit exposed for a while and see what happens.

I don't think I would be quite that extreme, but I might mix sand, clay and wood chips together (do the mixing when everything is dry), soak it with good compost tea and then plant with a nitrogen fixer and leave it alone for a year. I bet you'd have awesome results. I might give it a try if I can get my wood chipper running again.

--
Karen
 
R Scott
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In my experience if you add sand to pure clay, you will make bricks (literally). BUT if you get to a final mix of a clay loam soil with high organic matter, you are in business.

There also is the mineral side of sand--are you bringing in needed minerals or over-saturating some (like calcium/magnesium balance)? Are they bioavailable? Do they change the pH?

 
Jennifer Wadsworth
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Location: Phoenix, AZ (9b)
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R Scott wrote:In my experience if you add sand to pure clay, you will make bricks (literally). BUT if you get to a final mix of a clay loam soil with high organic matter, you are in business.

There also is the mineral side of sand--are you bringing in needed minerals or over-saturating some (like calcium/magnesium balance)? Are they bioavailable? Do they change the pH?



This has been my experience as well.

And as you say - some stuff is not bioavailable in some situations. Here in the hot desert - it tends not to be available due to alkaline soils/insufficient water.
 
Miles Flansburg
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I added about 1/2 inch of sand all over my garden about three years ago and forked it in to about 8 to 10 inches. Every fall I add about 1 ft of leaves on top and cover with branches to keep it from blowing away. In summer I add grass clippings as mulch.
So I have added all sorts of stuff.
The soil seems to be getting better.
I think the sand helped. I can see the grains mixed in with the clay.
 
Kelly Smith
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Location: In a rain shadow - Fremont County, Southern CO
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maybe there needs to be a distinction between clay with and clay without organic matter?

also, geoff lawton mentions something similar to Adam.
He added clay to a sandy area but didnt mix it in (to large of an area). after a few months the soil life had started to mix it in and later it was all mixed in and holding water great.

i sort of see it as "if you build it [soil life habitat], they will come"
 
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