# removing sodium with gypsum ?



## Joseph K (Feb 20, 2014)

So I just got my soil tests back on a new field and now they're worrying me a little. PH is between 7.9 and 8.3, with one particularly bad spot at 8.7. Recommendations call for some nitrogen and potash here and there, but mostly center around gypsum. The testing guy is a friend and labeled the three samples the good the bad and the ugly. The special comments and suggestions area reads

"Salts are high in bad and ugly, plant growth may be severely reduced."

"The SAR is very high in ugly, indicating that this soil is sodic. Plant growth may be severely reduced. Add Gypsum to help reduce sodium."

"Divide the Gypsum recommendation into three applications where one-third of the recommended rate is applied 4-6 weeks apart when the ground is not frozen."

"Add water with the Gypsum applications to leach it through the soil to remove sodium from the root zone."

the good calls for 40 lbs/A of potash, that's it

the bad calls for 95 lbs/A of nitrogen, that's it

the ugly calls for 70 lbs/A nitrogen and 2-3 T/A of gypsum.

Anybody ever done this, and have a real world outlook of how effective it really is? Also, how long term is something like this? Trying to reduce sodium like this I'm assuming is a very slow process? How much trouble am I really getting into?


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## endrow (Dec 15, 2011)

,, Sounds like you could use some help., there are going to be a lot of people on here that are not familiar with your soil type. Do you have an extension agent available. or an agronomist. After reviewing the data I have not always followed every soil test to the T


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## r82230 (Mar 1, 2016)

Endrow, hit a home run, your soil types are SO much different than what I have ever seen (or heard of).

Somewhere on HT there was a discussion about reading soil tests and something about CEC numbers. I wish I could find it but, this is where my computer skills are lacking. I personally, am going to try to get a better understanding about CEC, because I believe it has to do with how fast (or slow) soil additives go into (through) the soil structure.

Good news is that you did a soil test, bad news you already know.

Good luck.

Larry


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## reede (May 17, 2010)

The attached is a gypsum bulletin put out by Ohio State. Lots of good info in it. I am using it for different purposes, as I'm on acidic soil with the potential for Al in the subsoil. There is a section in there on sodic soils, though. Hope it helps.

Reed


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## Swv.farmer (Jan 2, 2016)

I use rock dust like you use in a coal mines it is one half lime and one half gypsum works great for me grass loves it.


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## hog987 (Apr 5, 2011)

I live on similar kind of land. High ph a little over 8 and high in sodium. First questiom is where is the sodium coming from? The sodium comes from the bottom up.

In my case its because I live by a lake. The lake for thousands of years water ran in, nothing ran out but the lake level would fall every year just from evaporation. Its a shallow lake maybe 10 feet deep at most. I have a few spots on my land where I dig about a foot and hit the lakes water table. So my sodium is coming from the lake water. I cant really change that. So I just have to grow something that will grow in these conditions.

Is there any chance you can drain the water table with tile or something? Another thing is to plant deep rooted crops to keep the water down and the rain fall will leach some of the sodium fown with it. But before you plant alfalfa get a test strip or a bucket full and make sure it will grow in that soil. I have some soil where the alfalfa wont grow more than 6" tall.

But I dont have any experience with using gypsum to help, just cause in my situation iam not going to easily get rid of the sodium but just have to work with it.


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## vhaby (Dec 30, 2009)

What is your source of irrigation water. You probably ought to have it tested for suitability for irrigation. Tests would include pH, calcium, magnesium, potassium, sodium, salt content, and a calculated sodium adsorption ratio (SAR). Your soil testing friend or CSU can do that for you.

If the salt and sodium contents are moderate to high with a high SAR in the water, the water will be the cause of the high sodium and SAR in the "ugly" soil. If, as previously suggested, you can get water to drain down out of this soil, gypsum, calcium sulfate, will be effective over time at removing the sodium down out of the root zone. This will occur by the calcium exchanging places with the sodium on the clay. The exchanged sodium will attach to the sulfate and move down, ever so slightly, where the sodium will reattach to a clay plate until the next calcium comes down from the gypsum and kicks the sodium off to again attach to a sulfate, etc.

If your soil has good internal (downward) drainage this process can work quite well. If not so good internal drainage, the sodium removal process will take a while. Regardless, you may need to create a series of levies that will allow you to pond water on the soil following gypsum application so that the water is forced to move down through the soil with a small amount of dissolved gypsum.

Alfalfa, or a salt-tolerant grass will be your best bet for growing on this sodium effected soil. Please check with you CSU Extension Soil Scientist at Fort Collins for additional information. This person may be Dr. Jessica Davis.

Best of luck- you will need it.

Vincent


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## Hugh (Sep 23, 2013)

Sodic soils are usually *deflocculated*. This means that sodium is separating the very fine clay particles. This makes for poor soil structure because these fine particles are separated by the sodium. When this type of soil is wet, it is sticky and slick. When it dries, it gets very hard. If you can get rid of the sodium, then the particles will "flock" together making small clumps, or flocs - BB size or there-a-bouts. With flocs, air and water will occupy the spaces. This is good for growing plants. The opposite is bad for growing plants.

Gypsum has calicum, and calcium will "grab" the sodium molecules away from the fine particles and permit these particles to floc together. This is called *flocculation*. If you irrigate, and your water has sodium, then using gypsum will be an on-going process. I'm not sure of the ppm sodium in irrigation water is the borderline, (rainfall vs irrigation etc) but you will need to find this out. All the best...


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## vhaby (Dec 30, 2009)

A pH of 8.3 usually indicates a soil is at equilibrium with calcium carbonate. A pH higher than 8.3 indicates a soil that is sodic. If your soil is saturated with calcium carbonate, it is likely that adding gypsum will not do much good, except that gypsum is relatively more soluble than calcium carbonate. A sodic soil high in calcium carbonate soil would benefit from application of sulfuric acid. The acid will dissolve the calcium carbonate, creating calcium sulfate- gypsum. You may be able to locate a source of used sulfuric acid called "spent sulfuric acid" and find someone to apply it to your sodic soil. This will accomplish the same thing as applying gypsum.

As Hugh mentioned, sodium disperses clay in soil. The sodium element is water-loving and continually draws shells of water around it. As more water surrounds the sodium, it pushes the clay particles farther away from each other, causing the flocculation of the soil referred to by Hugh.


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## Waldo (Apr 29, 2016)

We use ship loads of gypsum here heaps on irrigation country ,usually 2 ton to acre ever second year . Helps a lot with saline water also heavy clay country


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