Best way to amend clay soil????

[svendrix]

Greetings, question from a recently converted booholic here (took a chance trip to the PNW Chapter of ABS auction in July 2007 and little did I know how much I would enjoy getting into this). It's a little late in the year as we are getting pretty rainy, but I am asking now in order to prepare for next year. I built a house this year, and unfortunately had to cut down a lot of trees in the process, now seeing three neighbors close by. I originally looked into and purchased Thuja Plicata's after a web search, but after finding the boo, am thinking I will switch to Cold Hardy boo's for the border.

Unfortunately the biggest obstacle (besides finances!) is that my soil is completely clay. I have read some website that talk about amending soil using compost, humus, peat moss, etc, and wondered what people here have done in similar situations and had success with? Oh, and I'm a complete newbie to growing plants and landscaping, etc, so keep that in mind... =D

A couple of sites mentioned raised beds, and that it sounded like just having compost and amended soil on top of the clay might eventually break down and condition the clay into good soil over the years. Is my interpretation of that correct? I would think that I would need to plow the soil and mix it in that way like with a large rototiller. Only problem with that, is that I can't get a tractor to certain areas due to the slope and damage that would happen to my neighbors or my own asphalt driveways. Also a rototiller probably won't work here, as there are large rocks and boulders in the ground. I guess I bought a former lava field apparentlly.

Right now I am just slowly trucking in one yard of composted soil at a time when I get time, and just spreading it over the clay soil, maybe planning on making it like one big raised bed about 8" tall on top.

Thanks for any advice on this!
---Sven

[needmore]

Greetings, there is a wide variety of clay soils so I'm not sure what yours is like. Even on my property the clay varies significantly. For the most part it is not a problem for bamboo, I have some by my pond that is charcoal grey and extremely sticky/wet - I originally planted Atrovaginata here and moved them within 3 weeks as the leaves remained tightly curled due to the saturated clay. (Despite Atro's rep for wet site tolerance, you can not plant it in wet soil, but it may run into wet soil and be fine) That is the only soil I have encountered that was problematic for bamboo.

Other parts of my soil range from reddish clay to young sandstone and that is what most of my bamboo grows in. Minimal if any top soil to speak of. Bamboo is very tolerant of soil conditions, I do have some very powdery young rock soil that must be nutrient deficient as bamboo in that area seems a bit slow.

Generally when I plant, I dig a hole about 2x the diameter of the rootball and toss the native soil, backfilling with Miracle Gro potting soil. By the time the rhizomes hit the native soil they can handle it. If you mulch deeply several feet around the planting hole, the rhizomes will rise up into the mulch and grow in it.

Ideally if your site allows I would build a simple raised bed and fill it with good soil, but try to have some clay in it or the culms will lean too easily. My beds are about a foot deep, a bit more in some and that has been plenty deep.

I wouldn't bother with tilling, if you prepare the beds this fall the native soil will break down quickly under the soil in your beds. If you can get manure even better, when I prepare beds these days I put 2 feet of horse manure/sawdust down about 2 years ahead of planting and my voles come in and really mix it in the soil, preparing my beds for me/them. Worms and grubs come in within 2-4 weeks and the little rototilling moles/voles trench in after them.

[mantis]

My soil is 100% red clay. It doesn't drain at all. I plant all my boo very shallow, and they seem to be happy.

I know when my wife had a garden she'd throw down gypsum to help break up the clay, but I haven't done that with my bamboo.

[bambooweb]

I have clay here near Spokane and I put a couple of inches of compost on the ground and loosen the soil with a spading fork. I then build a mound to plant in with compost, clay and sand in whatever quantities I happen to have at the time. Over the years the compost will shrink but I add to it with new compost and straw added as mulch each year.

One advantage of planting in a raised mound is that you can see when the rhizomes get to the edge and you can deal with them.

Bill

[svendrix]

Cool, sounds like the recomposting over time will break down the clay, so I guess I did read that correctly! I am definitely adding some of the red/brown clay back into the composted soil I am bringing in, as we get a TON of wind here in the Columbia River Gorge (windsurfer central!). I have some tall trees around, but it is still so windy, and even more so since I had to deforest most of the scrub oak off the lot.

Bill, I think that your soil isn't too far off from mine (only 4 hours away!), so it sounds like I might be on the right track. Also I agree, one of the things I liked about the raised beds in this situation is that it will be easy to track down and prune the rhizomes. Its just taking so long to truck in 1 cubic yard at a time, heh. We have a temporary break in the rain, so I am going to pick up another load today at lunch!

For what it is worth, I am not sure what this composted soil is, other than it sounds like it is a combination of bark chips and mud/silt in the tanks of a local sawmill. It apparently is free of industrial toxins (they had it tested), and looks pretty fertile. It is pretty black and loamy, with lots of composting woodchips still visible, but it definitely looks more like dark soil.

Haven't come across the Gypsum idea, so I may look into that too. Needmore, it sounds like we are also pretty close in soil type, so I hope I can turn my small lot into a miniature version of your bamboo compound... =D I am definitely adding some clay back in so the wind doesn't overturn the upright culms. I am hoping to avoid staking them. For the 9 bamboos I have now, I have been adding a smaller proportion of sphagnum peat moss and perlite and sand to the mix of clay soil and composted soil I mention above. I was planning on this for backfilling the holes I dig in the ground when planting.

I still haven't decided if I'm going to plant this fall, or winter them inside my house. They are all Phyllostachys so are cold hardy, but they are still in 2 or 3 gallon containers at this point. I'm leaning towards wintering inside only because I don't know how much more of the good soil I will get trucked in before the weather starts getting too rainy and nasty.


---Sven

[BruceLofland]

I used this product on my soil: http://www.earlmay.com/cart/viewitem.ph ... &catid=145
It is essentially granules of clay pots. Since it is fired, it doesn't stick together and keeps the clay from sticking together but still retains moisture. I prepared all my bamboo beds with it before planting and they are all doing well. I have plenty of clay, more in some places than others. This product seems to have helped.

[pld5000]

I added tons to a property I had in Atlanta Ga. The county had a program that distributed ground-up, partially decomposed yard waste to various points in the city. I also added to the mix horse manure and black topsoil, which I bought. Some of the lessons I learned:

1. It is better to break up the top layer of clay very well and as deep as you can. This will help with water infiltration. Since water drains through the compost faster, and through the clay slower, you can easily have a root-rot problem. This depends on the grade of course.

2. If your compost is not fully composted, wait a year after the initial compost dump to plant any real valuable stuff. Even still, add lots of nitrogen to the soil, along with lime(extremely important), and gypsum.

3. You cant add too much. It is amazing how a depth of 4' wastes away to 1.5' in a year.

4. You will grow the biggest, baddest, most envious ANYTHING you want, including doorknobs.

[bambooweb]

2. If your compost is not fully composted, wait a year after the initial compost dump to plant any real valuable stuff. Even still, add lots of nitrogen to the soil, along with lime(extremely important), and gypsum.

The lime depends on where you are at. Here the soil has a natural pH of 7.5 so I have to add sulphur to make some of my bamboos happy. The gypsum will help break up clay if it is high in sodium but my clay is high in calcium so it does not help.

Bill

[southlatropical]

I am currently amending clay soil in south Louisiana. I turned it all over and chopped it up a little with the shovel. Then added manure and 40# bags of cheap potting soil. Then I topped it with live oak leaf compost retrieved from beneath the cast iron plants that surrounds my live oaks. I have bananas, iris, and other easy to grow stuff planted in it now. But by next year it should be suitable for anything. I used this same process in an area to plant P. nigra this year in early spring. The results have been great. Don't hurt your back heaving all those heavy chunks of clay. I did not add lime, maybe I should do that.