I live in SE TX, near the Gulf cost. I know our gumbo clay quite well. Some questions:

What part of TX? We have differing clays in different regions.

Will this be for permanent plantings, or annuals?

The best way to improve clay soil is to add organic matter to it. 6 to 8 percent organic matter will do remakable things to that clay.

Here is a link that might be useful: Amending clay soils

Kimm: that link says 25-50% on a volumetric basis, is your 6-8 on a mass basis (I assume)? Haven't done the math yet but, it seems 8% on a mass basis may exceed 50% volumetric.

Commonly used for OM in soils is weight fraction = 1/2 the volume fraction; e.g., 5 weight % OM ~10 volume % OM.

The standard soil lab number for the plow depth (~ 7") mass of common soils is 2 million pounds per acre. That translates to ~ 79 lbs/cu foot.

A 5 % by weight fraction translates to ~ 4 lbs per cu. ft..

Using finished compost as a model, with a typical bulk density of 37 lbs/cu ft, 4 lbs would be ~0.11 cu ft., or 11 volume % added.

The net volume fraction is then:
(0.11 cu ft)/( 1 + 0.11 cu ft) = 9.9 volume%

Hence 5% by weight OM is about 10 volume % OM in the soil.

My home is in Cypress, Texas. It is northwest of houston in Harris county. The house was built in 2008. I became interested in gardening and landscaping upon moving in and expanded the bed in front of the house and connected the bed in front of the house with a bed that runs along the side to the start of the fence. Hopefully the pictures help. I really didint know anything about landscaping and started planting. I planted shrubs, palms, annuals and some perennials. As you can imagine everything slowly died. So i did a little research tilled up the soil about 6" in depth and added some top soil, horse manure, and compost. I cant recall ratios or percentages because at the time I didint have a clue what I was doing. I knew once I started working the soil I was dealing with clay and it was extremely difficult. All of this took place over the course of one year. I joined the army and have been away for four years now. My concern is what to do with and to my soil when I return because I know my renters have neglected the yard so my plan is to start completely start from scratch with my existing beds. Advice and insight would be appreciated.

here is another pic of the side

Here is a link that might be useful: side view

I think I can help. BTW - thanks for the service, and welcome back to the Bayou City!

I live about 80 miles south of you in Brazoria County. We have very similar soils. It's commonly referred to as "gumbo clay". It is a dog to work with, but it's what nature gave us.

The first rule of living with this stuff is, for permanent or perennial plantings, like trees and shrubs, choose plants that will thrive in the native soil. There are many, many options. You will find them at good local nurseries. Avoid the big box home improvement stores, until you know what grows well. Then you can find some deals. But much of what they stock isn't really well suited to our soils.

The second important point is to maintain your base grade for drainiage with that native soil. That means you don't want to dig out the soil below that drainage grade, and then replace it with a high porosity, high draining amended soil. That leads to what is termed the "bathtub effect". Basically what you will create in that situation is an in-ground swimming pool for the collection of water when we get those toad-strangling Gulf cost T-storms. Instead of removing and replacing below the base drainage grade, you need to work mostly on top of that grade.

You can moderately amend the base soil in your landscape beds with up to about 5% by weight or 10% by volume of good organic material. Compost is the best if you have it or can buy it. Again, avoid the bagged stuff at the big box stores. Look in the yellow pages for a local supplier - check under 'landscaping equipment and supplies'. An alternative is hardwood mulch plus a bit of ammonium sulfate fertilizer, but that is a second option. If you need to go that route I can give you some numbers. For compost you want to apply one inch uniformly on top of the soil, then dig it in and mix it to a depth of ~ 10".

The third point - how to work in this stuff. First, it needs to be moist, but not soggy. It gets really heavy when saturated. Second, hand digging works best. This stuff is murder on rototillers. Get a rice shovel (looks like a heavy duty shovel with holes in it). Buy the heaviest-duty one you can find, preferably with a fiberglass handle. When you dig, think cutting slices about 1" thick the width of the blade. Cut it, pull it out, then turn it over and bang it down on the adjacent ground to release the slice. Do that repeatedly to create a trench. Then move over and do it again, and again, until you've loosened and turned over all of the soil in the bed. Then add your base OM amendment on top, use a garden fork plus your rice shovel to mix and distribute as best you can, then rake it out to your base grade. It will be quite lumpy - the clay never breaks up into what you probably think of as typical for soil. If you can get it to golf-ball size lumps, you've done well. It should gain about 1-2" in height. Let it settle for a few weeks before the next step. It is pure bullwork, but it can be done. Just take your time.

The next step is optional but highly advisable IF you have the room for it. Build a bed on top of your amended base grade. For this you buy good topsoil or garden soil (same deal on supplier). Build up as much as 4" on top while maintaining at least 6" and preferably 8" between where the finished soil level will be and the sill line between your slab and the brick ledge. That will allow ample distance below the sill line after mulching - you want at least 4" free. When figuring how much soil to put on top, allow for about 20% more as the added soil on top will settle about that much. So, for a 4" height on top, calculate using 5".

Then comes planting. Once suitable plants that do well in our soils are selected, plant them a bit high. Dig the hole so that the top of the plant or the container soil line is 2"-4" above the final bed top, and then use the soil removed to fill around sloping the soil out away from the plant down to the finished bed grade. Do that for all your plants.

Next is mulch. You will need to maintain a 2"-4" good organic mulch on top of your beds. I prefer a good wood mulch, which is widely available. In our heat with our humidity it will decompose quickly, so plan on remulching both in spring (early March) and again in fall (late September through mid October). You should plan on adding about 2" each time until you get it all figured out. The regular mulch additions on top will help maintain the organic material in the deeper layers. If you miss a year, it will be noticeable, and the beds will appear to settle as the OM in the soil decomposes and is lost. Once that happens, you really can't get it back up without digging and amending as this whole thing started. The goal here is to keep what you have.

That's pretty much it for the DIY approach. If you're not ready to sign up for the effort, there are many very decent landscape crews in and around the Houston area that work quite reasonably. Experienced gardening labor around here is abundant, and competitive.

Once you figure out what you want to do, you will probably have a bunch of specific questions. Come back with new posts and somebody here can probably help you.

This post was edited by TXEB on Thu, Jun 27, 13 at 22:48

That was extremly helpful. I have been doing a lot of research lately and you see and hear so many different ideas and suggestions and it gets overwhelming. I read the articles you suggested to someone else to read in another thread and they were very helpful as well. I will be back in Texas around the first of the year, would this be the best time to start working and amending the soil? I have never had the soil tested so that is what I plan to do first. Thank you again!

No problem. November to mid March is a great time to work in our soil, depending on what fall and spring rains bring us. You can do perennial plantings into and through April, and you'll be fine. If you plant any palm trees, save those for planting in late May through early June - they do better with warm soils.

The biggest mistake I see people make in our soils is to do what your original post stated - dig out the soil and replace it, or grossly over-amend it. Then they have lasting drainage problems, and the plants look great for a while, but that is often short lived and they are always fighting the drainage issue. The other is if they go about it the right way is then failing to maintain what they either worked to construct or paid for.

Good luck!

Spending money on something called "topsoil" without knowing what that is is largely a waste. If you wanted a room painted Robins Egg Blue but the painter you hired only paints with Fire Engine Red would you allow her/him to continue?
Animal maures, with 3 times as much vegetative waste, can be a good addition to any soil, because that is compost (almost) and compost is organic matter and organic matter is what any soil needs. A simple test is available to determine how much organic matter is in a soil and is listed below. How much to add depends on the soil yuou have because if your soil has no organic matter you will need a lot more to get to that 6 to 8 perecent level then if your soil had 2 percent organic matter.
Contact your local office of the Texas A & M Cooperative Extension Service about having a good, reliable soil test for pH and major nutirents done and then dig in with these simple soil tests,
1) Soil test for organic matter. From that soil sample put enough of the rest to make a 4 inch level in a clear 1 quart jar, with a tight fitting lid. Fill that jar with water and replace the lid, tightly. Shake the jar vigorously and then let it stand for 24 hours. Your soil will settle out according to soil particle size and weight. For example, a good loam will have about 1-3/4 inch (about 45%) of sand on the bottom. about 1 inch (about 25%) of silt next, about 1 inch (25%) of clay above that, and about 1/4 inch (about 5%) of organic matter on the top.

2) Drainage. Dig a hole 1 foot square and 1 foot deep and fill that with water. After that water drains away refill the hole with more water and time how long it takes that to drain away. Anything less than 2 hours and your soil drains’ too quickly and needs more organic matter to slow that drainage down. Anything over 6 hours and the soil drains too slowly and needs lots of organic matter to speed it up.

3) Tilth. Take a handful of your slightly damp soil and squeeze it tightly. When the pressure is released the soil should hold together in that clump, but when poked with a finger that clump should fall apart.

4) Smell. What does your soil smell like? A pleasant, rich earthy odor? Putrid, offensive, repugnant odor? The more organic matter in your soil the more active the soil bacteria will be and the nicer your soil will smell.

5) Life. How many earthworms per shovel full were there? 5 or more indicates a pretty healthy soil. Fewer than 5, according to the Natural Resources Conservation Service, indicates a soil that is not healthy.
to see what you have now and later to see how you are doing.

Here is a link that might be useful: TAMU CES

jarrod - when you get back you can use the Texas A&M AgriLife Extension Soil, Water and Forage Testing Laboratory for your soil analysis - link below. I would suggest you use the "Urban Soil Submittal Form". For your planting beds take a series of soil samples around the area in which you intend to plant - maybe 8-10 based upon the pics, blend them in a clean bucket, then send a suitable size portion (2-3 cups) of that blended sample as instructed on the form. I would suggest test 2 or 3 on the Urban form. If you want a lab to tell you how little OM is in your soil, then you could opt for test 7 or 8 instead. In our hot SE TX climate our soils don't retain much in OM unless they are well maintained. If your renters haven't maintained the mulch in your beds, I can pretty much guarantee that the analysis will be less than 1%.

kimm makes a good point on topsoil - don't buy it unless you know what it is. That's why I suggest staying away from the bagged stuff widely sold. A good soil yard can give you a specification for what they sell as topsoil. If you're dealing with a reputable soil yard in your area I can just about guarantee that it will fit the Harris County municipal specification for topsoil, since they are a very large gorilla in the local market. Here is that spec:
=========================================
ITEM 160 TOPSOIL
C. Imported Topsoil shall conform to the following requirements:

TABLE NO. 1
Specification
UNIT / VALUE
APPLICABLE STANDARD

Soil Reaction
pH / 5.5-8(a)
ASTM D4972

Passing No. 4 Sieve / % 95-100
ASTM D422

Sand Size, 2.0-0.05 mm / % 10-70
ASTM D422

Silt Size, 0.05-0.005 mm / % 0-40
ASTM D1140

Clay Size, ASTM D1140

Easily Oxidizable Organic Matter / % 2.5-10(b)
ASTM D2974
AASHTO T194

D. Topsoil shall have Liquid Limit

Here is a link that might be useful: Submittal Forms for the Soil, Water and Forage Testing Laboratory

What a test lab might desire "topsoil" to be means little in the market place where the definition of "topsoil" is very simply put the top 4 to 6 inches of soil. Most of the bagged "topsoil" I have seen is better then most of the "topsoil" I have seen available in bulk. At least those that bag soil seem to make an attempt to put out something close to loam that I have found over the years most people think "Topsoil" is.
However, putting enough "topsoil" down to actually do much good can be very expensive and still does not address the soils need for organic matter.

kimm - the base need for OM in the foundation soil was already addressed.

Bulk topsoil from a reputable yard that comes with a textural specification that meets a desired profile is cheaper and far more certain than the bagged stuff, where you have no idea what you're getting or where it's coming from. Because of the needs for physical soil stability in a permanent foundation planting bed, coupled with the local climate and environment, soil OM should be limited to ~ 5 weight %. That can easily be met with a very modest addition of 0.5" of compost for 5" of imported topsoil.

The addition of imported soil on top of the base grade clay was suggested to be limited to 4" after allowing for natural settling from loose to bank grade density. This provides a more porous mineral soil layer on top, which serves well to allow for the permeation of organic matter and water down to the underlying amended native base soil. With 4" of better draining more porous soil on top in a raised bed installation, it also serves to retard the natural decomposition of the organic matter that was added to the underlying native soil, thus preserving the improved texture of that underlying clay for a much longer time, and allowing for its maintenance via top dressing with decomposing organic mulches.

In the right situations there is nothing wrong with decent "topsoil", and it is readily available in bulk in our area (and with good reason). It is also cheaper and more stable than the blended garden soils, which around here typically come with 20-40% compost (usually derived from decomposed hardwood mulch), much of which will be lost within a year as the soil disappears.

It may not be a useful or even needed material in MI where you live, but down here it works quite well in the right applications.

This post was edited by TXEB on Sat, Jun 29, 13 at 12:36

jarrod - here is one example of a good soil yard in the Houston area. There are others. They have some good compost that is more than just decomposed wood mulch, and their enriched topsoil is a good product to use for that additional layer on top of your base soil. They are located about 30 miles south of your area, and deliver to Tomball, The Woodlands, etc.

Here is a link that might be useful: Houston area soil, compost an mulches

What I have seen pass for "topsoil" in Texas, Oklahoma, California, Washington, Tennessee, the Carolinas, and other places as well as here in Michigan would make a knowledgable gardener shudder. "Topsoil" in my gardens is going to be sand with maybe some organic matter mixed in while at my sisters (6 miles west) it will be clay with maybe a little organic matter mixed in. Between us is a landscape business that sells "topsoil" dredged from a swamp, mostly undigested tree leaves. Another business around here mixes the organic matter they dredge from one of the lakes with the sand we have, along with some lime, although they do not sell it themselves as "topsoil" Some landscape suppliers buy from them and do sell that as "topsoil".
Putting something called "topsoil", which most likely will be around 95 percent mineral on top of, or into, clay which is mostly, if not all, mineral, is simply tellong someone to through their money away since it will not last very long. Adding organic matter to clay soil, or sandy soil, or most any other mineral soil, will do more for that soil then anything else one could do. And yes you do need to keep adding organic matter to soil because that OM is the only part of the soil that is digestable.

"Putting something called "topsoil", which most likely will be around 95 percent mineral on top of, or into, clay which is mostly, if not all, mineral, is simply tellong someone to through their money away since it will not last very long. "

Huh? kimm, you obviously don't get it. Since when is a sandy loam topsoil "not going to last very long"? The one thing that would be a waste of money here is to amend the native clay with more than ~ 5 weight % organic matter, because there is hardly any way that higher levels can be maintained in permanent planting beds, and keeping even 5% takes regular maintenance.

I appreciate your MI experience (not dissimilar from mine). However, it is irrelevant to our situation in TX in the Houston area. The supplier example I provided above sells sandy loam topsoil. It will meet the municipal specification of the City of Houston and Harris County. That's not a soil lab desire, as you mistakenly commented previously - it's a major market buyer requirement in a very sizable market. The supplier also has to be able to identify the source location for selling topsoil, and the project engineer has the option of having it independently tested.

Buying topsoil is no different than buying any kind of soil or compost - get it from a good, reputable supplier, and know what you're buying. In spite of your objections, good topsoil has it's appropriate uses. The OP's situation is one of them, and as you might observe, it was noted to be an optional step, but one which provides advantages I noted previously. If you actually read what was posted you will see that the recommendation is to use the topsoil optionally on top of the underlying amended clay. It is a practice used by top landscapers in our area, and it works incredibly well for permanent planting beds. For beds dedicated to annual plantings a very different approach is preferred.

Sounds like Jerrod is plenty smart enough to decide whether the local expert advice or that from someone far away is the more valuable :)

jarrod - BTW, if the tree right next to but just outside of the bed that goes from the front of the house around the side to the fence is a southern live oak, it is probably too close to the house. They should be no closer than ~ 30', and preferably 40' or more from the slab.

My point is the buyer should be telling the seller what that buyer wants, not allow the seller to tell they buyer what the buyer will get.
Because "topsoil" is not the same thing every where telling someone to buy "topsoil" is irresponsible unless you define just what you mean by "topsoil".

kimm - with your first point I totally agree.

On your second point, you are correct, the generic term "topsoil" leads to significantly different products in different regions, end even with a fairly narrow area (we see that in Houston a lot). I have no problem with that - soils differ by region. But because they differ does not mean it is irresponsible to recommend the use of "topsoil" that fits a known soil type. That was done. Good topsoil serves a very useful purpose in our subtropical climate, and a number of different topsoils by texture description will serve that purpose quite well..

I still don't understand your comment "it will mostly go away". Sandy loam topsoil will be around as long as the native clay.

Wow! This is a great thread on how to take care of clay soil and make it productive in the landscape.

This is a great discussion about improving clay but as noted, especially in warm climates the organic material is soon gone and must be refreshed to keep the soil from packing back down. I'm surprised though that no one mentioned the use of expanded shale along with the organic matter.

Anyone care to comment on the success of first tilling in a combination of expanded shale and compost, followed by top dressing annually with more compost?

I have experience with using expanded shale. It's quite a weird product...good weird.

It works best being tilled in 6-12" in perennial beds at an amount of 1.5"-3" applied, respectively. It holds water (and water/nutrient solutions) quite well while breaking up the soil and allowing some oxygen movement through the root zone. Top applying with compost (as well as mixing compost in when you initially till with the expanded shale) works very well.

That said...I wouldn't recommend it for a veggie or annual bed unless you re-till your beds every few years. It easily comes back to surface when the soil is disturbed and doesn't return back into the soil very easily. While it's not bad on the soil surface, that's not where it's going to do it's job. It does little to nothing to add to the positive soil aggregation issue when it's not actively in the soil. I'd recommend gypsum and compost tilled in over expanded shale for veggie or annual gardens.

As an aside, I've also seen it used as a mulch. It's extremely light weight and allows water/oxygen infiltration into the soil...and lasts a very long time. It does a great job of keeping light sensitive weeds from sprouting as well as keeping out grass. Wind blown weeds can't grow in it...good stuff for low-maintenance plantings. The drawbacks are the dull grey color (which may or may not be a drawback) and the cost of using it as a mulch over a soil conditioner.

Also as another aside...I've been to a the manufacturing plant of an expanded shale maker. They occasionally use guns (like, the ones that shoot bullets) to blast away and remove huge chunks of the expanded shale that's left stuck on the side of the kilns after cooking. That was an interesting plant tour...and I doubt this is cross-manufacturer standard process.

This post was edited by nc-crn on Wed, Oct 16, 13 at 2:07

Expanded shale can be used in clay soils, just as sand can,, but you need to get that to around 45 percent of the total to make enough difference to be worthwhile.
Organic matter does not "disappear" it is converted by the Soil Food Web into plant nutrients. Ma Nature provides us with lots of organic matter every year because she knows the soil needs it, except many people throw that organic matter away.

There has been a lot of work with expanded shale in backland prairie clays in TX. This led to what is referred to as "EarthKind™ Soil improvement". The recommended method, developed by Dr. Steve George at TAMU, is to first till the soil to a 6" depth, then add 6" of 3/8" diameter of expanded shale and mix that in to a 6" depth (rasied bed by 3"), then add 3" of compost and work that in to a 6" depth (total bed height increase of 6"). It is stressed that the compost addition is a vital part of the bed using expanded shale.

I have no personal experience with the stuff, and I don't know anyone much using it in the Houston area. It appears to bring both moisture retention and water-dissolved nutrient storage capacity. However, in our area we aren't usually too concerned about moisture retention. Typically, it's just the opposite.

There is some good information on expanded shale and the benefits it can bring in a 2011 article available via the link below.

Here is a link that might be useful: Calcined Expanded Shale - Properties