What makes clay loam soil mysteriously become sandy?

[Shule]

Every once in a while, one of our planting holes seems to completely change its soil texture from a tough-to-dig clay loam into a very friable sandy soil that dries out really fast and needs to be watered super often. It doesn't seem to relate to fertilizer (this began happening before I began using fertilizer much). I'm sure adding organic matter could help, but lack of organic matter doesn't really seem to explain the phenomenon, does it?

I'm highly tempted just to dig the sandy soil out and put it somewhere else to get to the more clay-type soil beneath it. Maybe dig the clay out and put the sand on the bottom, or mix it all together.

[PlainJane]

I’ve never seen that. My experience with clay in Michigan was that it was very consistent and there was no change over time to any noticeable degree.

[Seven Bends]

Every once in a while, one of our planting holes seems to completely change its soil texture from a tough-to-dig clay loam into a very friable sandy soil that dries out really fast and needs to be watered super often. It doesn't seem to relate to fertilizer (this began happening before I began using fertilizer much). I'm sure adding organic matter could help, but lack of organic matter doesn't really seem to explain the phenomenon, does it?

I'm highly tempted just to dig the sandy soil out and put it somewhere else to get to the more clay-type soil beneath it. Maybe dig the clay out and put the sand on the bottom, or mix it all together.

Could it have something to do with runoff? Clay particles are more readily suspended in water than sand particles, and they stay suspended for a much longer time, so it seems logical that the clay could become suspended in water (from heavy rains, etc.) and run off, leaving the sand behind.

I'm having this problem in my own garden, while my mom's adjacent garden is less affected. Mine is on a slope, while my mom's isn't.

The other factor I'm wondering about is Asian Jumping Worms. They're present in my garden despite my efforts to eradicate them. They are known to destroy soil texture, though that's basically due to their eating all the organic matter. Maybe when all the organic matter is depleted, a clay soil feels more sandy?

[Shule]

Every once in a while, one of our planting holes seems to completely change its soil texture from a tough-to-dig clay loam into a very friable sandy soil that dries out really fast and needs to be watered super often. It doesn't seem to relate to fertilizer (this began happening before I began using fertilizer much). I'm sure adding organic matter could help, but lack of organic matter doesn't really seem to explain the phenomenon, does it?

I'm highly tempted just to dig the sandy soil out and put it somewhere else to get to the more clay-type soil beneath it. Maybe dig the clay out and put the sand on the bottom, or mix it all together.

Could it have something to do with runoff? Clay particles are more readily suspended in water than sand particles, and they stay suspended for a much longer time, so it seems logical that the clay could become suspended in water (from heavy rains, etc.) and run off, leaving the sand behind.

I'm having this problem in my own garden, while my mom's adjacent garden is less affected. Mine is on a slope, while my mom's isn't.

The other factor I'm wondering about is Asian Jumping Worms. They're present in my garden despite my efforts to eradicate them. They are known to destroy soil texture, though that's basically due to their eating all the organic matter. Maybe when all the organic matter is depleted, a clay soil feels more sandy?

While I don't think it's the water (since the climate is semi-arid—although we did get perhaps the heaviest rain I've ever seen a day or two ago), I wonder if you're onto something about the worms. I kind of wonder if wood ash or ground stumps can do that to soil over time, too.

I don't know if we have jumping worms, but I have noticed new worm behavior in the last few years. The worms seem to mound up dirt more by our porch, and they seem more drought-tolerant.

[Shule]

Another phenomenon I've noticed is that when tomatoes are growing in the planting sites, every once in a while, the soil heaps up around the base of the plant as if some kind of animal pushed it up out of the ground (and perhaps it tends to look kind of sandier; loose and friable, anyhow). The plants don't seem to mind that phenomenon, though, but they normally tend to struggle more in the other soil that turns sandy (except maybe Napoli).