Soils Analysis

[Ridgerunner]

@so lucky I was waiting to see if @MontyJ would answer. He’d do a better job than me and I’ll probably get something wrong. But still, I'll give the way I understand it. Maybe Monty or someone else will correct me.

The SO4-S is a measure of available sulfur in the soil in a form the plant can use. Sulfur is a critical nutrient.

CEC is about chemistry, the periodic table and how many electrons are circling the atom nucleus. If that doesn’t scare you I don’t know what will. I was proud of my 3 C’s in four college chemistry courses. When I didn’t take chemistry I often had straight A’s in engineering.

CEC is Cation Exchange Capacity and is tied to the pH. It’s a measure of how well the soil holds on to certain nutrients. Clay is highly charged chemically and does a real good job of holding on to the nutrients and has a high CEC. That’s also why it bakes as hard as a brick. Those charges really bond together on a molecular level. Sand is pretty much chemically inert and will allow those nutrients to escape so it has a low CEC. Pure sand stays loose. It does not form those molecular bonds. The plants can grab those nutrients pretty quickly but water can also leech them out fairly quickly.
My original pH was too low but that is the natural state of my soil and where it will want to return. I’ve brought it a little too high, but because I have a low CEC it will return to a lower pH a lot faster than if I had a high CEC. That’s part of why I’m not too worried about my high pH. It won’t last.

This is about making the nutrients available to the plants. It’s done by the electronic charges being able to access the nutrients they need. For example, if the soil has a lot of aluminum in it, the aluminum would tie up a lot of the chemical space for the bonds needed so aluminum in the soil would make the soil less fertile, not necessarily because the other nutrients aren’t there but because the plant can’t use them.

The soil is a system and it’s about getting that system in balance.

 

[digitS']

You know,

a lot of compost can be shoveled at science, and still,

it just never goes away.

Steve

 

[so lucky]

Well, I sorta understand that, Ridge; thanks for the explanation. Our soil around here is heavy clay. Your info helps explain why it holds water so long, and dries like cement.
I guess I need to take some soil samples in for analysis, to see if my additions of compost and chicken litter has helped at all.
I am constantly amazed at the wonderful variety of really smart (and generous) people we have on this forum.
You are all appreciated!

 

[thistlebloom]

@so lucky I was waiting to see if @MontyJ would answer. He’d do a better job than me and I’ll probably get something wrong. But still, I'll give the way I understand it. Maybe Monty or someone else will correct me.

The SO4-S is a measure of available sulfur in the soil in a form the plant can use. Sulfur is a critical nutrient.

CEC is about chemistry, the periodic table and how many electrons are circling the atom nucleus. If that doesn’t scare you I don’t know what will. I was proud of my 3 C’s in four college chemistry courses. When I didn’t take chemistry I often had straight A’s in engineering.

CEC is Cation Exchange Capacity and is tied to the pH. It’s a measure of how well the soil holds on to certain nutrients. Clay is highly charged chemically and does a real good job of holding on to the nutrients and has a high CEC. That’s also why it bakes as hard as a brick. Those charges really bond together on a molecular level. Sand is pretty much chemically inert and will allow those nutrients to escape so it has a low CEC. Pure sand stays loose. It does not form those molecular bonds. The plants can grab those nutrients pretty quickly but water can also leech them out fairly quickly.
My original pH was too low but that is the natural state of my soil and where it will want to return. I’ve brought it a little too high, but because I have a low CEC it will return to a lower pH a lot faster than if I had a high CEC. That’s part of why I’m not too worried about my high pH. It won’t last.

This is about making the nutrients available to the plants. It’s done by the electronic charges being able to access the nutrients they need. For example, if the soil has a lot of aluminum in it, the aluminum would tie up a lot of the chemical space for the bonds needed so aluminum in the soil would make the soil less fertile, not necessarily because the other nutrients aren’t there but because the plant can’t use them.

The soil is a system and it’s about getting that system in balance.

That was a very good explanation Ridge. I won't pretend to actually understand it, but I get the gist of it.

 

[bobm]

From what I have learned about our lot... this subdivision was built about 20 years ago on what was formerly a "swamp land". The developer filled in the low areas first with 1"-4" rough rock ( 6" - 2'deep) then added all manner of fill dirt on top of that. In our case, one low section of the lot, the rock is about 2" below the surface of fill. About 10' away and covers about 1 /2 of the back yard, the rock is about 10" - 15" below a layer of what amounts to silty sand. Rain water just about runs through it. The rest of the lot ( front and back yard) is black dirt with some sand in it. So, what would you recommend to rectify this sandy area so that I could plant some blueberry bushes, and other edible garden plants ?

 

[Ridgerunner]

Bob, others can help you more than I can about amending your silty sand soil. I just don't feel comfortable making suggestions when I'm sure others could help you more.

I used to live in south Louisiana. That swamp muck underneath your land is probably real high in really fine organic matter. When it gets wet it will swell and really hold moisture, plus be sticky and get on everything. It's a mess when wet. But when it dries out it shrinks and cracks. They have to take precautions for natural gas lines going into houses built on that because the shrinkage has been known to cause settling and break those lines in a drought. Since that vegetation rotted underwater, it was probably formed by anaerobic bugs which don't make as good a compost. It would still be rich stuff but not quite like what we think of compost.

Blueberries are kind of tricky. I have three bushes. They require a real low pH, somewhere in the 5.0 to 5.2 range. My soil was low in pH to start with and I still had to work in a lot of sulfur to get it lower. Another thing is that they have a shallow root system. They need to be on well drained soil because the roots can die if they stay wet. But since the roots are shallow, they can't handle dry conditions too well either. I carry a lot of water to my blueberry bushes in the summer.

 

[bobm]

Our area has an average rainfall of 38" / year. last week we had 2 1/2" of rainfall ending yesterday early morning. I can dig in this sandy area today as it is mostly dry already without having huge clods. Would adding and working in 1" or 2" of peat moss plus about 1" of aged steer manure help remedy this situation in tilth, fertility, lowering pH ( our average pH is 6.8 )as well some water retention ?

 

[Ridgerunner]

Yeas, peat moss and aged steer manure will help. How much and how long the effects will last I'm not sure.

 

[MontyJ]

Sorry folks, I've been really, really busy! I have to assume the "E" CEC is the Estimated CEC. Ridge did a pretty good job of explaining it.The CEC or Cation Exchange Capacity of a soil basically gives a snapshot of the soils ability to hold certain positively charged ions (cations). Cations include Calcium (Ca), Magnesium (Mg), and Potassium (K) as well as Aluminum (Al) and even Hydrogen (H). Some of those nutrients are useful such as Ca, Mg and K. However, others are not such as Al and H. As Ridge said, the CEC is closely tied to pH of a soil, but is not influenced by it. In other words, the pH determines to some extent what nutrients are occupying the exchange sites, but cannot add to or take from the available sites.

Let's look at it this way...

There is a train station (the CEC) The station can hold 100 passengers waiting for the train (the plants root). If the station is clean and nice (a good pH) the station will be filled with 100 good passengers (Ca, Mg, K) waiting to go to town (the plant) on the train and go to work. However, if the station is nasty and dark (low pH) there will be a lot of undesirables hanging out. The more bums in the station dealing drugs (Al and H), the less room there is for the hard working ions to come in. The result is, there are fewer hard working ions to go to work, and the plant suffers.

Obviously, that's a gross misrepresentation of the Cation Exchange Capacity, but it's a good analogy. Clay based soils and soils high in humus are like a larger train station. Sandy soils are like a small train station. Cleanliness and good lighting (a healthy pH) determines what hangs out in each particular station.

Oh, and yes SO4-s is soil sulphate.

 

[MontyJ]

From what I have learned about our lot... this subdivision was built about 20 years ago on what was formerly a "swamp land". The developer filled in the low areas first with 1"-4" rough rock ( 6" - 2'deep) then added all manner of fill dirt on top of that. In our case, one low section of the lot, the rock is about 2" below the surface of fill. About 10' away and covers about 1 /2 of the back yard, the rock is about 10" - 15" below a layer of what amounts to silty sand. Rain water just about runs through it. The rest of the lot ( front and back yard) is black dirt with some sand in it. So, what would you recommend to rectify this sandy area so that I could plant some blueberry bushes, and other edible garden plants ?

Bob, without a soil test to examine it would be nearly impossible to make any kind of recommendation. So if I understand you correctly, you have rock about 10-15" below a silty sand? I can pretty much guess the CEC is very low. Large amounts of compost, tilled as deep as you can till it will certainly be a start in the right direction. Keep in mind that anything you do will take some time to correct a sandy soil since much will leach down and away until it builds up.