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How do I amend black clay?

Posted by maden_theshade 8 - Austin (My Page) on
Thu, Apr 3, 08 at 15:43

Hello! I just moved to a lovely new home. It is close to a creek. The parts of the yard that are not bedrock have this thick, black clay type soil. When I dig in it, I do not find too many worms. :-(

what can I do to amend the soil? The previous owners let the yard get a little weedy. I've been pulling up tons. The turf is a mix of StA and a little bermuda. The neighbors on one side have TONS of weeds and most of the yards in the area seem to have some problem w/ weeds. Always heard weeds love poor soil. Would love advice since I've never dealt w/ this kind of dirt! Thanks!


Follow-Up Postings:

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RE: How do I amend black clay?

We mixed sand, peat moss, and compost into ours when we wanted to make a garden.

The black clay is a pain, but it holds water well which is a real plus for plants. My black clay has lots of nice fat worms, it's not poor soil, just hard to work with for us gardeners.


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RE: How do I amend black clay?

Coffee grounds. I have the other kind of clay - thick heavy yellow clay, and I never used to see any worms. After dumping in loads of coffee grounds over the past few years (and peat moss & hummus), I see tons of worms. Happy!


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RE: How do I amend black clay?

Texas A&M will test your soil for a nominal fee (get with your county extension agent - he/she will have the sample bags/bottles). I have tight black clay soil up here north of Ft. Worth. Soil analysis was not as I expected. I should have used different fertilizer.

J.D.


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RE: How do I amend black clay?

Texas Plant and Soil lab is a lot better than Texas A&M. Organic program will dramatically improve clay soil unlike synthetic fertilizer. So basically, you'd need to put down compost at the rate of 1 yard per 1000 sqft which is light dusting to introduce beneficial microbes into the soil then you apply organic fertilzer every few months. You can get them at animal feed store. it's just ordinary animal feed like soybean meal, cottonmeal, alfalfa pellet, corn gluten meal and corn meal. My preference is soybean meal because it is easy to spread by rotary spreader and good amount of protein (nitrogen). In a few years, you will have excellent soil teaming with soil biology (earthworms). You cannot use any chemicals that ends with icide because they tend to ruin soil biology and making it a lot harder to improve the soil.

To speed things up a bit, you can put down molasses every 6 months. That will ramp up soil microbes population.

What everybody doesn't realize is that improved soil will gradually weaken weeds over time because of the condition. For example, weeds thrives on high level of nitrate (type of nitrogen) and it is commonly found in lawn that is fertilzed by synthetic fertilizer. That's why we have all kinds of herbicides...

You have st augustine so you can slow weeds down or gradually choke them out by mowing high at 3-4 inches (4 inches is best during hot weather). You MUST water them when needed. It should be 1 inch of water everytime you water them. I've improved my rocky soil to the point where I can go as long as 2 weeks during hot weather before I water st augustine again. You probably can go a long time because clay soil hold a lot of moisture but you need to improve the soil first to take advantage of it. You must help support earthworm population because they will do the aerating for you. They can go pretty deep allowing roots and water to go deeper. Anyway, my general rule of thumb on watering is when the lawn is 50% wilted, water deeply. You may have to use soaker hose at first because clay soil in poor shape do not absorb water quickly enough.

Do yo have any mature trees? The fall leaves are great way to add organic matter to the soil and feed the earthworms so pull out your mulching mower and mulch them into little pieces that will fall to the ground for earthworms to munch on and get fat and poop out great stuff that will really help plants do better.


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RE: How do I amend black clay?

If you truly have clay soil...go the organic way. It's not recommended to dig in amendments very much because a lot of shoveling--or worse, a tiller tends to compact it. here I can make clay pots practically. I keep mowing over leaves to leave them on the lawn (no pun intended) and leaving the grass clippings. The clay is still horrible (I plant stuff that can survive it well, or use raised beds.), but for the first time this year, I saw earthworms when I was digging in that stuff. Before there were absolutely none. And I have not tried a program like lou suggests (I'm a little lazy and short on budget most years)....but that is certainly the way I would go if I wanted to speed up the process.


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RE: How do I amend black clay?

Hi, I'm in central Austin and probably have the same soil. I moved into an old home about 3 years ago and didn't know much about the soil here, nor lawns. And finally I've figured out that clay isn't the problem. It's hard to dig into, and if you want flower beds, you'll probably have to make raised beds. I spent a few weekends last fall hauling around a soil/compost mix (I had delivered from the Natural Gardener in Austin) to make all new beds.

But with a lawn, you don't have to worry about having clay. After a year or two of doing some basic organic care, you will notice your lawn filling in and the St. Augustine taking over the weeds. I even got it to take over Bermuda last year by letting it grow higher, as Lou suggested. St. Augustine is pretty tough.

It's kind of a pain in the booty to spread around compost on the entire lawn but everyone says this is probably the best thing you can do for your lawn. Now is the time of year people recommend doing this in Austin. (I see lawns all over our neighborhood with compost in them!) I also take the time to spray it with Ladybug Terra Tonic about once a month during the growing season (which is a mix of seaweed, compost tea and other soil goodies that you can get at almost any local nursery in Austin). You will notice worms by the end of the summer if you do either of these, or both.

I didn't use any fertilizers last summer, just the above two, and my lawn is getting better and better. So basically it is about making the soil more fertile organically, than making it 'less clay'. Hope this helps!


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RE: How do I amend black clay?

In flowerbeds, I spread expanded shale. It is a gravel sized, 'popped' rock that is porous. Shale in the top foot of your soil allows air and nutrients to move around. The soil will drain faster allowing more plants to survive. ES is getting more popular with the garden nurseries, so you should be able to find it in bags. We did all our beds at once and had a truck load delivered.

We've found that a constant moisture level is critical to having an active earthworm population. When it is bone dry, the wormies dig deep and hibernate. Mulch helps tremendously.

Here is a link that might be useful: Creative Soul


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RE: How do I amend black clay?

Lots of advice -- most good but I'll put in my 2 cents.
If preparing beds, till the soil (make sure it's not WET-
damp, not wet) 6 - 8 inches deep. Lay down 2 inches of a mix of expanded shale and a GOOD quality compost with little
sticks in it that snap in two, not bend. Till again. Add 2 more inches of ES and Compost, Till, Add the third layer of 2 inches of ES and Compost, till. Plant , add 3 inches of hardwood mulch. Your are through. Every year add about 2 inches of hardwood mulch (not cedar or cypress). The breakdown of the hardwood mulch is constantly providing additional nutrition. Plant hardy, Earthkind or native Tx plants. It IS a lot of work at first, then SOOO easy to care for. Like a good paint job----it's all in the preparation.


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RE: How do I amend black clay?

I have the blackest, tightest clay in my yard and have fought it for years. First I made the mistake of mixing in regular concrete sand in my garden (20'x20'). It turned to concrete that summer...hard as a rock. Finally, after several failed attempts to amend my clay (a couple of years I just tilled it really good, but it packed back down before the summer was over)I went to the City Compost facility and got a cubic yard of compost for free...then tilled it in my garden area as far down as the tiller would go. I rented the biggest tiller that I thought I could possibly handle at Lowes. The next day I went back to the Compost facility and got another cubic yard and tilled it in with the previously tilled soil. The compost facility calls a cubic yard a "scoop". Well, a scoop is equal to the amount that a huge front end loader can scoop up at one time. It filled the rear of my truck and mounded up almost to the top of the cab. But, so far the compost has worked out great. I use mulch, but not cypress mulch (it packs down). I like little hard wood chips the best--they break down over time and don't pack together. For the past 2 years I have been mowing my autumn leaves with the bagger. When the bagger gets full, I take it to my garden and sprinkle them on top of the soil. I put about 4 inches of coverage all over my garden and flower beds. Then I take the bagger off and mow the rest of my leaves and leave them on the lawn.
This Spring, I was removing extra leaves in some of the areas where I wanted to plant some transplants and my garden is full of huge earthworms. Everywhere that I dug I was bringing up earthworms..lots of them.
I don't till my garden every year now since I have perrenials now. But i don't have to anymore. I have stepping stones throughout the garden so that my foot traffic doesn't pack down the soil, and the decaying hard wood mulch and leaves naturally break down into good soil. Every now and then I take my garden fork and work it through the soil just to keep it loosed in some areas.
I now have what is called "good garden soil"...loose and rich and full of worms.
good luck. I had to wheel barrow my compost from my truck back to my garden and then shovel it over the clay before I could till it. It took 2 long, full days to finish it and 3 days to get over being sore. But once done, I have not had to do it again....5 years ago.


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RE: How do I amend black clay?

Thanks for all the great advice! Looks like I need to get a bigger worm bin so I can create mini colonies in the yard! I also picked up a couple bags of Dillo Dirt for now until I can try some of the other suggestions. I live close to Round Rock Gardens now and feel lucky they have a lot of Lady Bug brand and other organic products and actually have staff that knows how to use them! I'll be asking them about some of these ideas!


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RE: How do I amend black clay?

Xeriscaper - We did basically the same as you, only we skipped the tilling completely. put thick layers of compost, leaf mulch, and grass clippings everywhere we wanted beds, then caught some tree trimmers for a few dumptrucks full of their chunky mulch. In about 6 months, things were looking good, and we dig down and find gigantic worms all over the place. I'm working in an area now that's very packed down clay, trying to get a little ground cover started. I've been bagging lawn clippings and piling them up in a small section, and it's already looking so much better when I dig around there.

I really don't think you can ever mulch enough in Texas.


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RE: How do I amend black clay?

I think what Lou is talking about - the light dusting of compost - is look for top dressing. But, just about any compost will break down eventually and help build your soil and keep your plants healthy. Encourage the St. Augustine since it will choke out the weeds and even the Bermudagrass. It is even tolerant of a little bit of shade. Someone also mentioned coffee grounds. Starbucks used to give away their used coffee grounds to gardeners, but I don't think they have that program anymore. It wouldn't hurt to ask a local coffee shop that if you brought a clean bucket if they would deposit the used coffee grounds in it for you to pick up later in the day. Earthworms love coffee grounds and it doesn't hurt the soil either since most of the acidity has been brewed out of it. My husband has a little one cup coffee maker and I even take that little filter out and dump the coffee into my garden.


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RE: How do I amend black clay?

I just became the proud owner of a lovely 1950s home in Central Texas, and I'm looking into how to work with my black clay soil, too.

We have St. Augustine grass, and I plan to keep only a limited turf area. This might sound like a dumb question but, uh, how do I add compost to GRASS? I can't really till it into the soil without ripping up the grass, can I? How do you get it in there? Just dump it and leave it? (Can you tell I have never had a lawn before?)


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RE: How do I amend black clay?

For grass you use sifted compost and just spread it about a 1/2" deep a couple of times a year. It takes a couple of years but it really works. The earthworms like the mulch and come.


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RE: How do I amend black clay?

Good compost seems to be the key. I used to use peat moss, but it was expensive, didn't work all that great and I read recently in Howard Garrett that it is anti-microbial. Expanded shale is said to be the best for clay, but it costs $9.99 for a 40 lb bag at the nearest nursery (maybe it will become cheaper when the big stores start carrying it). If you have the money, good compost, Texas green sand, expanded shale, and time will do wonders.


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RE: How do I amend black clay?

Ditto. No tilling compost,compost,compost... PJ


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RE: How do I amend black clay?

Basilete, there are no "dumb" questions on this forum. :-)
To add compost to your lawn, just dump the compost and very gently rake it where you want it. Making sure that it gets below the grass blades and goes down to the soil. Some people use a push broom instead of a rake. Just make sure the compost goes all the way down to the soil -- don't leave it on top of the grass.

I have dark clay soil, too, and I'll tell you, once it's composted, it is the best soil medium around. I didn't till anything into it (it would have been impossible to run a tiller through that concrete-like soil anyway), but slowly added compost to it -- Starbucks used coffee grounds, cotton bur compost, mulched grass clippings, leaves, any organic matter I could get my hands on, and everything covered in mulch. And now the soil is like butter, and dripping with earthworms.

Starbucks does still give away used coffee grounds, usually bagged up in a bucket near the door. If you don't see any, ask one of the workers if they have any ready to give away. If the bag is big enough, they'll usually carry it to your car for you.

Carla in Rowlett


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RE: How do I amend black clay?

LOTS of grass clippings, compost from the kitchen, ground up leaves in the fall, lava sand, green sand, tea & coffee, sand, we've used it all but I think the grass & leaves are the best. Throw lots of worms in there.


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RE: How do I amend black clay?

So I did put Dillo Dirt (that's compost, right?) right on top of the St. Augustine last spring. Just cut open the top of the bag and slowly drug it across the yard to spread a thin layer. Then used a rake to spread it some more. I wish I had thought of the broom - that's a great idea! Then I watered it in.

I haven't gotten to do it again yet...but I will say that I'm seeing fewer of those little pony foot weeds. Last spring they were rampant under one tree. Everything I read said they crop up where you have drainage problems. So the Dillo Dirt really helped!


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