It took about 48 hours for my sample to clear. I kept thinking the cloudiness was due to clay but when everything settled, I just had finer silt. The silt layer of your backyard sample looks good!
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Hi Winn
Your clay is more than 25-35% of total. The loan looks ok but I might suggest adding river sand to increase your coarser amount to about 65%. It would be in the ideal zone then. If you have drainage issues or lack of tilth the excess clay would probably be why. But if your plants are doing well, it could be your organics are contributing to your CEC since you have some darker color. Good test!
Awesome. A bit of advice from a geologist, always keep in mind when looking at a geological map the scale of detail that it was mapped at and how homogenous the materials involved could be. The glacial sediments in that area are complex, especially the late glacial deposits from when the ice sheet was melting. Those tend to be varied and messy due to the ever-changing network of meltwater channels and ponds on the surface and underneath the glacier. The Qvtm description you shared does a good job of illustrating that. You could have anything from well sorted silt and clay to very coarse gravel within the same map unit.
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Floodplain/overbank deposits tend to have excellent texture for farming soil. Hence the largest floodplains already being full of farms!
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I think it will be very little clay once it settles out, that photo shows it still in suspension right after shaking, but I’ll post another photo in a couple days and we’ll see then.
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Very true, thank you for bringing it up! There’s also the fact that there was quite a bit of leveling done when this area was cleared for building, so humans have made the messy deposits even more messy.
Our neighborhood has some great dropstones hiding deep under the surface, I found one big chunk of smooth granite (or something that looks granite-y) that must have come quite a way from its source.
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The is the bluff I just checked out. The base is pure clay with chunks scattered at its base.
I put a scoop into a shake jar and will wait a few days to see how it settles.
Nearby signage:
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Those yellow and gray/white chunks are very nice! But be very careful to not undermine the bluff to cause it to fall on you!
Dennis
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Typical screening job, For clay clumps
I break them up with a large stick on my 1/4” screen, then screen out all stones larger than 1/4”, then I wash the stones to remove all fines and use that slurry to water my raised beds which will be planted in spring with strawberries.
The wood chip perimeter is inoculated with mycorrhizae to feed the plants that grow in the center. For winter I am growing a clover- pea cover crop
Dennis
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Once screened the remaining stones are seen to be very rounded, a sign of much grinding and washing action in the glacial moraine while the glacier was receding, hardly any sharp angular stones
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The development property that I visited this week is only about 3 miles along the same moraine as mine. Today I took a pic of one of the cuts by equipment to show the soil profile down to about 10’. The topsoil goes about 12”-15”, then the clay starts. There are very few tree roots in the clay. As I tried to dig any undisturbed clay I understood why! I Found one completely oxidized rock about a foot long that fell apart as I dug. The giant boulder in one pic illustrates the range of rock size that the glacier carried.
Sidewall of cut
Closeup of cut sidewall
Giant boulder:
Dennis
Kent, wa
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23 hours in and there’s a clear clay line on the back yard sample, which may get slightly thicker by tomorrow, but I’m guessing not much:
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Agree, you could actually add clays to get closer to loam, on a limited scope small plot it would be easy to accomplish.
Dennis
I am tempted to modify my title to Teaching Moments! Last night at dusk as was hastily digging into the gray clay deposit on the builders site, a rather large red stone broke in half as my shovel struck it. This being so unusual that I picked one half up only to have it fall apart into several pieces. Even more unusual, so I assembled this group for the below pic, this stone most probably made up of iron ore had completely oxidized disabling all the minerals polarity that once bound it together. Surrounded by the moist gray clay inside the earth it most likely traveled here during one of the six different glacial invasions of the state. I scraped away the clay from one edge to reveal what the interior of this 12”x3”x 4” stone looks like. pic #1: In the foreground is some of the stone pulverized between my fingers, the rub test reveals no sense of grit but more like a powder texture. To the right side you see a piece of the outer shell of a different stone that must have been beginning the same process, but the 3” diameter inter core was still solid stone.
Pictures like this conjure up the imagination of how nature performs such miracles to form the soils we all depend on.
Dennis
Kent, wa
Pic #1
Pic #2
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I added a scoop of clay to my 50/50 sand/silt jar. Now I have about 40/40/20 sand/silt/clay - the perfect mix. But I’m afraid I’m approaching obsessiveness if I bring home clumps of clay to add to beds!
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For your soil, you are already near what some would consider excellent, but your test illustrates that only small increments can make a big difference, which is why I think the shake test is the simplest but most productive test you can perform. As noted among many members fruit trees do not require perfect soils, but for small plots such as raised beds you can certainly elevate the potential of soil with this test that tells you quickly what to do next. This next year I will make several test grow areas in my gardening areas to evaluate the difference clay amendments can make.
It’s unlikely something that weak would survive the forces of glacial transport. It could be cemented sediments, maybe iron oxide cementation from mineral rich groundwater or something related to human activity. Any idea about what that site might have been used for in the past?
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It was all forested so within the past years there was no substantial human activity that I can imagine. This development removed all trees and striped topsoil to create housing foundations as a new subdivision.So the glacier left it much as the developer found it.
Dennis
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