It all depends on the amount of sand used.

Soils are drained and aerated due to the size and number of macro-pore spaces in the soil. Sand particles are large, clay particles are very small. If you put a lot of large sand particles together they will not fit together well and in between will be the macro-pores. If you put a lot of clay particles together they will fit closely and there will be few if any macro-pores.

If you have a clay soil and add only a small percentage of sand, the clay particles will surround the sand and there'll be no increase in macro-pore spaces. If you put in enough sand so that the sand particles begin touching each other, you'll improve the number of macro-pores and improve the structure of the soil.

How much sand do you need? If you had a clay soil with no sand and you wanted to add sand to the point where the texture became a sandy clay, or a sandy loam, you would need to have at least 60 percent of the soil be composed of sand. A loam soil is usually classified as 50 percent sand, 30 percent silt, and 20 percent clay.

A better way of improving a clay soil is through the addition of organic matter. The organic matter binds, or collects, clay particles together into larger aggregates; these aggregates for large size particles that improve soil macro-pore numbers. Calcium and magnesium also bind clay particles together in larger aggregates (the process is called flocculation) and creates more macro-pores. This is the bases for adding lime or gypsum to a clay soil to improve the structure.

So, adding large amounts of sand, 50 percent by volume, will improve the drainage and structure of a clay soil. (Actually how much sand is needed really depends on how much is already there). Adding small amounts will not improve it. Will adding small amounts of sand make it worse? No. But it might disappoint the heck out of you when you were expecting such good results.

Have a nice day. (IronBelly?) Significance?

Bob (in Maryland)

Bob,

Sounds like the old "soil triangle" that I studied about 25 years ago in agronomy class at Iowa State.

Thanks for the knowledgeable response.

IronBelly

Both of you have made some good points. My own personal feeling is that you don't grow plants, you grow healthy soils and you can't keep plants from growing.

When I was a kid, we moved onto a place where the garden (nearly half an acre) was almost pure clay covered with a huge crop of weeds. My Dad mowed off the weeds, and hauled several large loads of manure onto it. All the leaves we raked up from the yard (surrounded by trees) were put on top of the manure. All winter long, we heated with wood and coal, and all ashes were added to the menu of the garden. In the spring, It was all plowed under and disked. We had a good garden that year. Each year we continued with repeats of the leaves and ashes. The third year, I joined 4-H garden project and we had to keep track of the value of the produce. Dad, an excellent carpenter, earned $4000. The value of produce from the garden was over $1000.

I have often added sand to my clay soils, always an improvement. My mother is on pure clay and I am on pure silt, just a little coarser than clay. We continually haul buckets of soild from one place to the other, improving beds in each place.

Pottery clays are different from most ordinary clay, and I think this is where the sand added makes the hard coating.

IronBelly (totally ripped abs??), I think your original post contains the answer along with your question. Two points: As you pointed out in quoting DiSabato, it is the amount of sand one must use--"30% by volume" (or even 50%, according to Bob) would be necessary--while the average person probably goes to K-Mart or Lowe's and figures he's solved the problem with a 50-pound sack or two of play sand spread over his/her whole yard. And then you mention the real clincher: you "strive for... 1/3 soil, 1/3 sand, AND 1/3 COMPOST." (Emphasis mine.) As Bob and Barb both pointed out, and with which I wholeheartedly concur, the addition of organic matter is the deciding factor, the absolute necessary third part of your "soil triangle." I have personally seen the liberal use of mower-chopped leaves do wonders for both clay and sandy soils. Well, anyway, had to add my 2 cents. CK

Hi IronBelly,

This thing of not adding sand to clay has been quoted frequently and seems to be a standard concept. However, when you add lots of humus to the soil at the same time the soil does seems to get better. For example, one end of my garden area had a bunch of leftover sand thrown on it and the rest is heavy clay. I have added lots of humus such as leaves and shreaded plant material over the past four years. The end that had the sand is much softer and doesn't stick together like the end with clay and humus only. So sand does seem to be benefical if used with a lot of humus added. So I have to agree with you. Sand is fine for adding to clay, provided humus is also used.

Edd

Is it safe to say that just as there are many different
soil compositions there are many different clay
compositions? Could it have anything to do with what kind
of clay you are dealing with? The adobe clay of our area
is composed of fine clay particles, quartz and other
minerals. Adobe has great plasticity when moist, but when
dry tillage is impossible. When organic matter and sand
was added to adobe (in the 1/3--1/3--1/3 ratios) and it was
allowed to dry, the bricks for the construction of the
early California Missions became possible. The "recipe"
for adobe bricks is documented and is in our state's
archives. I don't have immediate access to the
information, but I know from personal experience that
adding organic material and sand measuring in quantities
less than tons per 100 square feet creates a conglomerate
worse than abobe clay alone. This doesn't happen when just organic material alone is added. Master gardeners and nursery personnel alike advise against adding sand to adobe, not because if enough added might not work, but because small amounts make things worse. To noticably change the quality of the adobe is totally impractical. To improve adobe using sand and organic matter you would need to raise the level of soil 6-10 FEET! Not something an urban gardener is capable of doing.

What about adding gypsum to clay soils? What does that do?

Steve,
Gypsy, calcium sulfate, improved clay soils through a process called, "flocculation." The problem with clay soils is that the individual clay particles are very small, so small that they fit together closely and there is little room in between the particles for open spaces. Open spaces in soil (called pore spaces) are important for air movement into and out of the soil. In clay soils, the tiny spaces between soil particles is usually filled with water instead of air. Roots need air and don't grow into soil without it.

The calcium in gypsum (the calcium in lime works the same way) attracts the clay particles into groups or aggregates, this is the flocculation process. These groups or aggregates are much larger and more irregular in shape than the individual clay particles, thus they don't fit nicely together, and they create bigger spaces between them. This allows excess water to drain out and air to move in.

The problem with using gypsum, or lime, to improve clay soils is that these materials have to be MIXED with the clay, not just dumped on the surface. Organic matter will also create clay aggregates. This all leads us back to the necessity of working clay soils and incorporating amendments, whether they be lime, gypsum or organic matter. It's the incorporation process (digging up the clay soil) that results in all the work. People are always looking for something to just sprinkle on the surface and make the clay soil better; there ain't no such thing; at least not yet.

By the way, the difference between gypsum and lime is related to changes in soil pH. Lime improves clay soils and raises the soil pH, makes it less acidic. Gypsum improves clay soil but doesn't change the pH.

Bob (in Maryland)

I absolutely agree with Barb and Carol. It is the addition of compost that makes the difference.

Sand will change soil texture but it will do nothing to change soil structure. Therein is where organic matter/compost/humus does the job.

You can add sand to clays but it will only give you something like grainy peanut butter. Sand has no electrical bonding capability, no nutrient holding ability. It is essentially, 'inert'. Just like a carrier on a herbicide is used to carry the active ingredient.

It will help with porosity, air space and thus drainage, but to actually improve the vitality and life of the soil it does nothing.

Fact. I've done it succesfully with some of the worst clay soils known. Clays which totally absorbed all organic matter of all kinds and quantities in one year were rendered essentially permanently workable by adding copious sand. It's back-breaking work and does require a hefty percentage (I wouldn't argue with the one given). And adding lime to such amended soil does NOT create concrete! After I sold that place, though, I swore I'd never buy on clay again. It's not worth it: you can fix the garden and aise shrub beds but what about the lawn and everything else (by the way, your HOUSE is still on clay). No thanks!

Bologna.

Just try applying all that mumbo jumbo to Texas alkaline (8.55PH) clay soils. We can add sharpe sand or poteet sand but not regular sand. But the real key to working our clay is organic material, water, a good mulch layer, and patience. Our clay is extremely expansive and I have actually watched it rise during rare periods of rain. But there is a point of dryness that it actually sheds water and doesn't absorb in. The water beads up. As an aside to this question, some kids in town are building a house from bricks they are making by adding sand to our clay mixing it with cactus juice and drying in our sun. Very nice adobe. It's the same recipe they used to build the missions.

Has anyone use EnviroMax (used to be called SoilMaster RX) for clay soil. Tobby Tobin on Kansas City radio station Saturday morning garden show is always talking about spraying this on clay soils.Suppose to work after 2 applications to loosen up the soil probably about 2 inches deep. Ingrediants are polmaleic anionic terpolymer 34.3%,maleic anhydride sulfonated copolymer 10.8% and inert ingredients 54.9%. It is about $75 a gallon. He says he has treated yards where water drains fast and yard dirt is soft after treating it. He talks about it so much I'm beginning to wonder if has some type of monetary interest in the company. Its by ChemCraft, INC. in Overland Park, Kansas.
I heard is was developed for the carrot industry to loosen up the soil. Is their anything out their cheaper then this stuff?

I know the original post was about adding sand, but then about adding gypsum. Here's the scoop on gypsum....

Here is a link that might be useful: Is Gypsum a Gyp?

Gypsum does not always appear to work on the heavy, locally compacted clay around my home, but when a gypsiferous clay is attacked by a diggin' iron it forms crumbs instead of powder, and does not readily revert to a cloddy or amorphous mass.

Calcium nitrate (15.5-0-0) is also good to use on clays and its aggregating effect is often noticeable at once when a solution is applied.

-Tony

Gypsum is supposed to help clay soils by binding the sodium. The sodium is what can clog the soil pores. The sulfate in the Gypsum combines with the sodium to make sodium sulfate.

I agree with Larry on sand plus clay. The soil here is a very fine clay. The previous owners of this property amended the front lawn and some of the flower beds with sand. Under the lawn this has turned into a tough layer of sanded clay, which is worse than the clay alone, because it does not soften when moist. I have resovled the problem in the flower beds by working in 4 inches of organic compost into them. They are much improved after this. From my experience, I would not recommend amending clay soils with just sand. Compost is a much better solution.

Oscar Meyer

Rich,

The problem with Larry's analogy with adobe bricks is that it totally ignores soil structure. Soil is so much more than a just collection of materials.

Yes, I imagine if any of us would take our soil (even mine) and mixed it into the soupy consistency required to form bricks, we would all wind up with something pretty hard when it dried out. Even my 4 year-old niece can make some pretty hard mud pies. The fact is: you just don't amend garden soils this way.

To the nonbelievers, I say try the 1/3 clay, 1/3 sand, 1/3 compost mix in a small test area. Try it and see if works.

Rich - As to your previous owners; I doubt that they put on anywhere near the 30%(+) sand required.

IronBelly

Not an expert but I do know if one was to try this you have to use builders sand or sharp sand...granules with angular edges....not rounded grain beach sand. The CA mission adobe brick recipe most probably used beach sand since so close to the ocean....the sea minerals in that sand may have also added to the recipe's ability to make concrete hard bricks. The angular profile of coarse sand helps with drainage. But humus is a must for great soil.
Claire

My dad is building a golf course. He was telling me of the sand clay mixture that they are using from Tupelo MS. They hall is all the way to Springfield LA. The mix cost $10,000 per 18 wheeler dumptruck load. It looks like orange sand. That is what they are using on golf courses before sodding. It must be good. Studies show.

Boy am I glad you all get along so well.. from a visitor point of view. My instructor once told us that in the case of CLAY the soil can act like clay even if it is only 20% clay, because the clay fills in between ANY other partical size (pea gravel include and I tried it! kids experiment dang if that clay didn't hold that pea-gravel into a bowl even wet no water went through). So, if you have 1" of clay to be reduced to 20% by volume, you need to add 5" if sand, you want to go down to root level, that's 20" of clay, thats 100" of sand, I'm 60" tall (5 feet) the math is rediculous, sand doesn't work... compost it. even at 40% you can't possibly add enough sand without making the first floor of your house a new basement! the only thing that works are organics which 'glue' the clay together forming larger particles, so compost it.

OK, nmb. You have successfully extrapolated an isolated fragment of information and taken a quantum leap into the ridiculous.

IronBelly

First I want to thank you for your warm and tactful approach, and I will forward your comments to my soils science instuctor.
Since you are apparently so knowledgeable about the subject, given 100% clay, root depth or 20", and using the intitial 1/3 sand suggestion of the first message, please, tell us how MUCH sand would be required to have 20" of pure clay reduced to 1/3 clay? The numbers aren't mine, they're from previous messages.

I usually try to avoid certain subjects. Politics and religion are obvious. Organic gardening and soil are almost as bad -- sometimes worse. Gardening topics are every bit as filled with passion and opinion as the first two topics. However, a good deal of hard science can also be isolated, quantified and cited when it comes to topics related to growing plants in soil.

I don't come here to argue or pontificate. Quite frankly, I don't give a damn what anyone believes or does with their own growing medium. I have heard and seen "proof" about twenty different ways, many in direct conflict, on the "right soil". I have even heard and seen convincing presentations on why we shouldn't even use soil at all -- hydroponics is the answer.

In general, useful discussions of soil begin to falter when they become too scientific. There are many things happening in the soil and I am still convinced that nobody yet fully understands this topic. There are simply just too many variables.

Give me your scientifically perfect soil and by simple compaction, I can make it virtually impossible to grow anything in it. That is why you can still (2002) see vestiges of the Mormon and Oregon Trails meandering across undisturbed portions of our country.

My original suggestion (I don't like being misquoted.) is an easy to remember, nontechnical way for Joe & Jill Average to improve (maybe not perfect) their soil. Coarse sand was only one half of the recommended amendments -- an equal amount of compost was the other ingredient.

I believe that common sense and some moderation is the key. Studies out of the Chicago area are beginning to strongly suggest that: Yes, Virginia ... you can add too much organic material to your soil. The examples that I know of (and have actually visited) involved applications of mushroom compost. Yet, in spite of the evidence, it is not hard to daily find a zealot confidently claiming that you can NEVER add too much compost.

Give me a Shelly in Tupelo, Mississippi citing actual experience over remnants of professorial lecture any day. If the specifics of this lecture are not quoted any better than my printed words at the beginning of this thread, perhaps the professor's intended, larger concept was also missed.

IronBelly

IronBelly,

I have a question. Going back to the comment posed by NMB (which seems quite logical). If I have all clay soil in my yard how much sand and compost would I have to add to my garden area in order to improve my soil to a depth of 18"? I dont dispute your figures or the concept that enough sand will help clay soil, however, i need to come back to what is practical. Even 12" of sand and 12" of comost would be impractical. That is 2ft. I might as well build a raised bed. And from what I have been reading 12" of sand and 12" compost are not enough to improve 18" of clay.

How about putting the facts and figures into perspective. I am planning on doing a small garden (12x20). My soil is fairly heavy clay. Give me the proportions of compost and sand that I will need to add to my garden plot.

I am not trying to be contensious as much as I am trying to put all the rhetoric into real life practice. Theory is nice and makes for some interesting conversation. But, lets get down to some actual suggestions and recommendations.

I am planning on preparing my new bed during the summer for a winter crop and for next year.

Thanks,

TomN

Tom,

Most gardeners make two major mistakes:

1. They make gardening too much work.
2. They make gardening too complicated.

We are not talking rocket science here. We also are not talking about perfection. We are talking improvement. Even if you add Âgenerous amounts of both coarse sand and compost to your basically clay soil and work it in a spade depth or as deep as your rototiller will go, your garden soil should evidence much improvement. Will you have achieved the arbitrarily perfect depth of 20 inches of Âperfect soilÂ? Probably not. However, you will have improved it immensely.

Will most people be willing to haul in huge amounts of compost and/or an aggregate material to improve drainage? Once again, probably not. Most will just buy a bag of Miracle-Gro. The whole point of this is to give Jill or Joe Average an uncomplicated concept and approach that they can grasp and implement with a reasonable expectation of success. I usually tell people to just eyeball the one-third amounts of sand and compost and till it all together. In reality, Joe and Jill Average can usually accomplish their project with a few wheelbarrows of amendments. Your 12 X 20 project is more ambitious.

One, as yet, unspoken factor here is the immensely important addition of air to the soil in this amending process. Air exchange to the roots is a vital factor overlooked by most and one that will never show up on a soil test. By the time we have mixed these three products up, entrained air will add to the depth making the resulting depth greater than the sum of the parts. Here, one inch of clay plus one inch of sand plus one inch of compost does not equal three inches. Air adds to this dimension. And that is a good thing, as Martha would say.

If you only add a light sprinkling of sand, you are wasting your time. It takes a lot of sand to make a difference. If you must choose between compost or sand  without question, go with the compost. However, if you have quantities of sand available and only smaller quantities of compost, I suggest going with that. Many people do not have the luxury of copious amount of compost available to them at reasonable costs. I do and I have a pickup truck to haul it. Once again, many people do not.

For your 12 X 20 plot, you are probably looking at 4 to 5 pickup loads of compost and a similar volume of coarse sand. (Roughly calculating, a mini-size pickup bed holds about a cubic yard when level full.) Of course, I donÂt think you want to load a mini pickup level full with sand! My full size pickup will almost haul two yards of compost with a utility box on it.

You will obviously not be able to incorporate such large amounts of amendments all at once. When preparing new beds, I usually hand dig small beds a full spade depth. For larger beds, I till as deeply as I can with my big tiller (8 to 10 inches) and then begin to mix-in layers of sand and compost. Is this a...

When I lived in Riverton, Utah, I had a garden full of clay. We would haul in topsoil & sand by the truck-full - it just eventually washed thru, I guess, cause even when tilled in, it only lasted 1/3 to 1/2 the season, before the soil was back to its hard, true clay form. I tried peat moss, gypsum, and finely shredded grass clippings from my 1/4 acre yard and several of the neighbors were giving us theirs, too. Nothing seemed to work for long. The closest thing to helpful was the grass clippings, but even those semmed to work themselves back up to the top layer and become thick mulch (just what I needed-- NOT)

I finally called the Extension service in desperation -- their advice: sawdust!
I asked three different master gardeners -- I couldn't believe my ears. I thought you should never add "wood" to your garden cuz it just sucks out the nitrogen. When I asked the last MG that question, they said, Well yeah it will. Mix in Ammonium Nitrate (I think that's what it was called -- a common fertilizer) too.

I found a sawmill near my home that made oak furniture & cabinets, and they gave me all the 33 gallon garbage bags I wanted full of very fine, and best of all, very FREE sawdust. We tilled that in and it worked!

After all that, the next year, I was diagnosed with MS and couldn't do the big 25'X 30' garden anymore, so I had to do just a little container gardening instead. I was gonna convert it all to sq-ft garden, but we had to move, so it never happened. (boo-hoo)

I've been gardening in the black clay of Dallas TX for about 15 years and am glad that I added sand(not the 30% people talk about). Actually, I added some silt too after looking at the triangular soil diagram. They help keep the soil airy and give it a pleasing, friable texture.
The adobe/cement analogy is invalid because soil is alive and that stuff is dead. Yes, I do add compost to keep the soil alive and know that it has a greater effect than the sand on the texture.
Sand never goes away - it's a one time investment. Compost must be replentished and it's hard to have enough.
Have the "don't add sand" people ever done it and had a bad experience? Sounds more like theory from a textbook.

Danl_k

Ironbelly,

How can you say
I don't come here to argue or pontificate. Quite frankly, I don't give a damn what anyone believes or does with their own growing medium. I have heard and seen "proof" about twenty different ways, many in direct conflict, on the "right soil".

You started the thread by asking the question "Fact or Baloney?"

Let's remeber to get along.

Many of the above posts are correct. Gypsum doesn't help a clay soil... it helps a sodic clay soil. Very rare in Central Oklahoma.

Sand can help if added in larger volumes. 30-50% are good. Small amount won't help and could hurt.

Compost is king.

Remember, root depth is according to what you are growing. Most lawns only need 3-6 inches to perform pretty well. Yes deeper is better. 6 inches clay soil, with at least 2 inchs of sand and 2 inches of compost will make a difference.

Don't forget to mulch the surface so it doesn't dry out and crust over.

Maybe we are all full of baloney?

Paul,

This thread started just shy of 5 years ago. Thanks for finally joining in. I'm a little bewildered as to what your point is but....

Check out another (current) thread that essentially deals with this same topic. You are sure to enjoy it as much as this one. ;-)

IronBelly

Here is a link that might be useful: Head In the Sand

sorry I didn't check the dates.