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Any experiences with caliche?

Posted by idaho_gardener 6a_sw_idaho (My Page) on
Tue, Jul 6, 10 at 14:01

Three years ago, I discovered caliche in my yard while digging a hole for a tree. About three feet down, I hit a layer of soil that was about like concrete. (Next time I'll pour some Phosphoric acid on it and wait. :)

Since then, I've become a little more informed about caliche, its origin, and its nature.

This summer, the city started converting a farmer's field into a city park with two ponds. While walking through the excavations, I found caliche about 5" thick. It seemed to be forming at a depth of 3-4 feet. The pond excavation has a clear ring of whitish material at that level. In other locations where they dug out the topsoil to create parking, they dug down to the caliche and stopped there. (I wonder if they realize that they're paving on that layer?)

The field has a history of being farmed in corn, wheat, and turf sod. I suppose that it has also seen use as a potato field at some point. Irrigation was either flood irrigation, or a pressurized sprinkler system. The general environment is somewhat dry with average rainfall in the 10-11" year range, mostly in the November through May timeframe.

In the southwest, I hear that caliche forms very near to the surface of the soil. In the east, (in Connecticut) I found caliche while attempting to dig a hole for my sister's spruce trees. That was a surprise.

I am curious to hear how people are dealing with caliche in their areas.

Follow-Up Postings:

RE: Any experiences with caliche?

Dynamite really helps. If you run into a layer of it while digging a hole, whack a few holes into it with a pick and then pour a gallon of pool acid on it. Just wait until the fizzing stops and then toss in some baking soda to make sure the acid is all gone before you add water.

It dissolves into a soft, porous stuff.

The best way to deal with it is to break through it and plant a few trees with deep roots, such as mesquite. Those roots will break up the layer of caliche and then water will drain better and it all gets much better for gardening.

RE: Any experiences with caliche?

Pool acid would contain Chlorine, which would be pretty hard on the soil life. I was thinking Phosphoric acid would dissolve the Calcium Carbonate and leave some Phosphorus in the soil as a side benefit.

I'm going get a piece of local caliche to use for some chemistry experiments; effects of Phosphoric acid, humic acids, and water.

RE: Any experiences with caliche?

"I was thinking Phosphoric acid would dissolve the Calcium Carbonate and leave some Phosphorus in the soil as a side benefit. "

What's the level of P in your soil now? Much of the soil in the intermountain west is already high in P, so adding more isn't necessarily a benefit. Sulfuric acid (or Sulfurous acid) might be a better choice.

RE: Any experiences with caliche?

Margaret Lauterbach gardens in Idaho, organically, and probably has some good ideas to help resolve your question.

Here is a link that might be useful: Margaret Lauterbach

RE: Any experiences with caliche?

"Pool acid would contain Chlorine" ... use H2SO4, not HCl.

RE: Any experiences with caliche?

Don't put too much hope in humic acid. Humic "acid" is a misnomer. I have no idea why someone decided to call it that. It's actually a relatively strong base in most cases, with a pH of around 11. Sometimes more, some times less, but I've never seen it outside of the alkaline range.

RE: Any experiences with caliche?

I have caliche anywhere from being right on the surface to 18" below. My caliche is 26"+ in thickness so it's not just a simple task of pounding it. I have used a back hoe to make holes and trenches but it takes some time. I have started using a 3600 PSI pressure washer to cut into the caliche. I have several holes started and am keeping them wet to help dissolve and soften up the caliche. So it's a slow process.

I do think I'll try adding some pool acid to see if that helps. Once I have a small hole I can put cuttings into it to take root.

RE: Any experiences with caliche?

I believe humic acid's name comes from its functional definition -- it is the organic fraction that readily dissolves in an alkaline (usually mineral hydroxide) solution. Tannic and fulvic acids have related definitions.

And as others have said, I'd go with sulfuric acid. The reaction product (gypsum) is of known innocuous character.

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