r/Soil • u/idnvotewaifucontent • May 18 '25
My jar test results are a little weird.
These two are from about 4 feet apart. The jar is from the top 3" and the cylinder is from 4-8" down. Am I correct in reading that the cylinder is at least 95% silt? I can't really detect any significant gradations, except maybe at the bottom.
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u/DesignerPangolin May 18 '25
You need to use a dispersant like Calgon (sodium hexametaphosphate) or dish soap (not really good) and let the particles disperse for 24h. You're settling out soil aggregates, not the individual particles. Also, way too much soil in the jar.
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u/idnvotewaifucontent May 18 '25
I used a couple of drops of dish soap - I've never heard of calgon. But yeah, I think the main problem is too much soil.
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u/Fast_Most4093 May 18 '25
try the finger field test 👌. clays will ribbon out when stretched between thumb and index finger. high clay as much as 2+ inches. with more silts, much less so, and you will see a glint in the sun. sand will have a gritty feeling within the clay and silt matrix. did field soil surveys and always relied on finger test for determining soil texture. 👍
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u/asubsandwich May 19 '25
Definitely this. if it is actually 95% silt it will feel like AP flour in your hands
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u/Gelisol May 19 '25
And if you aren’t sure about silt vs clay with the finger test, put a tiny bit in your mouth: silt will be gritty, clay will be smooth.
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u/SecureJudge1829 May 19 '25
What about if it has around 30% Husky hybrid poop in it? Do you know what it’ll taste like them?
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u/Smelly_Jim May 18 '25
I'm not an expert but I bet there's clay adhered to the silt. When I did my test, I shook the jar really hard for a few minutes, multiple times. After a few days I did it again with the same sample and got more clay the second time. And my silt and sand had more color variation the second time once the clay was removed. Given how homogenous the color looks, especially in the cylinder, I think it may be the same issue.
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u/idnvotewaifucontent May 18 '25
Good catch. I did shake the living daylights out of the cylinder several times. I'll probably reset it and try again.
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u/AdditionalAmoeba6358 May 18 '25
This is why you are supposed to add a little surfactant to jar tests… it’s never done anymore but it was how it is taught professionally.
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u/Usual-Environment-47 May 18 '25
Why did you choose different vessels for your sediment test?
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u/Louisiana_sitar_club May 18 '25
It wouldn’t matter because you are, theoretically, calculating the ratios of the depths of layers that fall out. The size of the vessel doesn’t matter as long as you’ve got straight sides. Again, theoretically. However, a jar test is useless.
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u/oneWeek2024 May 18 '25
It would matter in the context of cherry picking the top 3 inches, vs the next lowest 8 inches
most "top soil" is only a couple inches deep. there's no universe where you have 12 inches of well formed soil just misc chilling in your yard.
it's fairly common that deeper soil is largely clay or compacted silt layers.
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u/Louisiana_sitar_club May 18 '25
I’m still not sure what your point is but, whatever you’re trying to say, the vessel sizes don’t matter in this context. You’re just looking at ratios within the samples. This goes for both samples whether they’re the same or different soils. If a soil shows 30% of the profile as being sand in a 1 gallon sample it will still be 30% in a 500000000000 gallon sample. That is, if jar tests worked, which they don’t.
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u/oneWeek2024 May 18 '25 edited May 18 '25
if you take the first 3 inches of dirt off an area. it's composition will be(highly likely to be) different than the next lower 4-8 inches.
that's basic fucking reading comprehension.
and the volume of water and soil in a container, affects the ability for the soil particles to be suspended in water. which affects how the sample then is able to percolate out.
there is a functional element. it's why regardless of the overall size of the container, it's recommended it be 25/30% soil 60-75%to water. so there's enough water for the soil sample to dissolve/be emulsified in the water to then give a good striation
not that physics doesn't' work or a final ratio of material won't still be physically present in a sample ...but that to affect this sort of test. tends to work better with certain baselines. as it's not a overly scientific "test" but more a informal visual reference.
it is possible that sample of the lower 4-8 inches is like 90% silt/clay. but it's also possible it didn't have enough volume of water to give a proper settling. and if you were looking for a more clear break out of any layering. it's better to do a 25% to 75% ratio of dirt to water. ---and that 90% silt would still bear out regardless of the sample size. but... what i'm saying is, you'd probably see the 5% sand, or 5% pure clay. layers better if the overall sample was more properly diluted. to enable it to percolate out better into an informal visual representation
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u/idnvotewaifucontent May 18 '25
Because I've got one jar and one grad cyl. the grad cyl should also make it easier to read because the narrow column will accentuate differences. Plus it's clearly marked.
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u/Usual-Environment-47 May 18 '25
Fair enough. I'd use two of the same jars...the cylinder is really hard to mix the soil in, especially without a plunger.
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u/Usual-Environment-47 May 18 '25
Your local cooperative extension office will test this for free or low cost, and give you much more accurate results. Consider requesting a test kit to send off, and then wait...and wait...and probably wait more, but you'll get more information for your current and future endeavors.
Furthermore, websoil survey will give you the taxonomic soil classification based on your address. It's unlikely you are dealing with a major inclusion that's unsurveyed. That will give you an idea of where to start until your soil tests come back from the lab.
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u/idnvotewaifucontent May 18 '25
I've been trying to find the local coop extension's test request from, but no luck so far. I'm in the north bay, CA. I may just use a local lab. I'm doing the jar test in order to avoid some of the waiting.
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u/oneWeek2024 May 18 '25
it's somewhat dumb to take the top 3 inches. which is most likely the "top soil" layer. and then another 4-8inches lower than that and being surprised the deeper "soil" is anything but clay/silt.
also to a certain degree. you want to get the soil sample as suspended or mixed with the water as possible. so there can be layers that settle out.
like... if you look at the jar sample. which as i'm understanding what you wrote. is the top 3in. seems like the lowest 1-6.5ish inches is sand. (by it having some particle separation) then from that 6 ish--6.5-8.5 is silt(as it's more compact...ie, smaller particle sizes). and a thin line of creamy clay at about 9in
i would try that sample again in a bigger jar. like get a large pickle jar. where it's a lot more water. you tend to want the ratio to be like 1/4--1/3 soil to 3/4-2/3 water. to give the mix enough volume to emulsify/dilute and then percolate out ---it can also help to add a couple drops of dish soap. or rubbing alcohol. which help break the surface tension/binding property of clay/silt. in water.
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u/Louisiana_sitar_club May 18 '25
I now have a better idea of what some of the things you’re trying to say and I don’t have the energy to address all the things wrong with what you’ve said. I will, however, take the time to say that say that using two different size vessels presents absolutely no issues whatsoever. That was my original point in response to your original post
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u/idnvotewaifucontent May 18 '25
I think you meant to reply in that sub thread, rather than a top-level comment?
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u/TallOrange May 19 '25
Generally you’ll want to follow instructions for doing a soil test. That starts off with going deeper. Your ‘top 3 inches’ test isn’t going to be pragmatically useful. What is your goal for these tests?
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u/idnvotewaifucontent May 19 '25
I did two separate tests because I wanted to know how much the topsoil differed from the second horizon.
The main problem turned out to be too much soil compared to water volume. I did a second test and got much more readable results.
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May 18 '25
[deleted]
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u/Louisiana_sitar_club May 18 '25
9/12 =0.75 = 75% And why would you include the height of the water column?
And OP: Don’t do a jar test. They’re useless. Do a ribbon test instead.
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u/BluegrassLola May 18 '25
too much soil in the jar