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White soil

Posted by ocgf Z8 (My Page) on
Sat, Dec 2, 06 at 21:30

We are building a house in Kyle, Tx and I noticed that the soil on the site is almost white. What the ....? I haven't tested it yet but there is some low vegetation growing around so I'm assuming it is not sterile. I'd like to hear from people with similar soil and how they handle it.

Omar


Follow-Up Postings:

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RE: White soil

I'm curious to hear from the experts. Is it limey soil?


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RE: White soil

I think it is what is called "Caliche". It looks very soft. Some references I checked state that the soil is a "calcic soil", white because its mostly calcium carbonate, the same mineral that makes up limestone. According to that source (University of Austin), Calcic soils form in desert areas where the rainfall is low. The rainwater is absorbed by the soils, but the soils are so dry that the moisture stays in the top few feet of the soils until it evaporates or is taken up by plant roots. The rainwater has minor amounts of calcium carbonate, either particles that have dissolved in the water or tiny dust particles, and the calcium carbonate is left behind in the soil when moisture is evaporated or used by plants. Over many years so much calcium carbonate is added to the soils that they turn white. Over thousands of years so much calcium carbonate is deposited that a rock-hard caliche is formed that may be several feet thick.

I have the theory down, what I still need to find out is how to handle it I can grow whatever I want on it.

Omar


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RE: White soil

  • Posted by jean001 z8aPortland, OR (My Page) on
    Sat, Dec 2, 06 at 23:19

Phone your county's Extension Service office. It's very likely they have Master Gardeners who supply folks with information appropriate to the region.


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RE: White soil

Caliche is a layer of calcareous soil that has solidified, it is very nearly as hard as concrete but you can soften it by soaking.

Your soil is probably full of calcium carbonate. It doesn't come from rainwater but is there because the area was once the bottom of the sea. The calcium carbonate used to be coral or the skeletons of other sea creatures. Depending on conditions, it can form into limestone, chalk, or marble. All these are very soluble in rainwater, but the only calcium carbonate in the rainwater before it hits the ground will come from dust in the air. Once it hits the ground, the calcium carbonate dissolves and you get hard water, plus caves. In wetter climates it tends to erode away or get buried by layers of more organic soil.

There isn't a huge amount you can do to alter the basic (basic means alkaline, that's a pun!) properties of the soil Mildly alkaline soils can be made acidic by the addition of sulphur but a soil like your's would need more sulphur than the whole state contains. You'll have to grow plants that can tolerate alkaline conditions, there are more than you might think. Addition of lost of compost on a regular basis will help to provide nutrients that would otherwise get locked away in alkaline conditions.

Soft calcareous soil is OK, but in your location there is probably a layer of caliche at some depth. This can cause problems by preventing root penetration and restricting drainage. At the very least you should investigate whether you have such a layer and how thick it is. Then you can consider whether you want to punch through in places for particular deep-rooted plants or to alleviate flooding problems.


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RE: White soil

Welcome to my world!

When the land by my house being cleared for new phase of my subdivision, the ENTIRE place was WHITE. I guess it was shocking since it used to be green/yellow. The caliche soil goes pretty deep. There's no telling how deep it is. There used to be 2-4 feet of black clay based topsoil (very rich nutrients) that they scraped off...

On the bright side, no worrying about the foundation shifting! :)


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RE: White soil

Thank you jean001 and shrubs n bulbs. The soil we are talking about is not hard at all, au contraire, it's dusty and floffy. I do need to call the Extension Office and I guess I will have to wait until I occupy the house in February to dig in and find out how deep the white soil is.

Omar


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RE: White soil

Chalk was my immediate thought (most famously in Dover in the UK) but I don't think it is soft or fluffy. Your situation is best determined by testing or by reviewing soil data previously collected for your area.


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