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sheet mulching compacted clay?  RSS feed

 
Angelika Maier
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Location: cool climate, Blue Mountains, Australia
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I don't know were to put this it isn't exactly about huegelculture.
We have a very compacted thin poor soil which is 10 cm deep at most and underneath is fill, some soil, concrete, pavers roadbase...
I tried to build huegelbeds on the top of this soil, because digging a trench is incredibly hard there. I would certainly dig over a week for just one bed and break several handels.
The huegelbeds did fine as long as the weather was very wet. But not it goes back to dry and they are a nearly complete failure.
Now I think of trying sheet mulch. It is easy work. But how does sheet mulch do with less rainfall? I don't want to build timber frames around as this is expensive and not practical. Am I able to build up enough soil or will I have to bring in stuff every year? It is quite clear that no root can break through concrete under the thin topsoil so the roots would mainly be restricted on what is on the top. Is it advisable to buy soil? I mean the cheap stuff which is not topsoil. I usually buy cow manure and mushroom compost in bulk and spent lucerne hay. I can buy woodchips by the truckload. I can get some lawn clippings for free. What are your experiences?
 
Brenda Groth
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i have deep clay soil..but I don't have the rubble problem (except where a houe burned and that has a lawn/drive over it.

I would try to locate where all the rubble is and put drought tolerant species there..if it was an old construction area or whatnot..if possible have a backhoe or something dig up the area and remove the rubble..otherwise if you can't..make use of it for the drought tolerant species on top of it.

then find any areas where the soil may be deeper for planting trees and shrubs or plants that need a deep taproot.

the hugel beds might need a drip irrigation system on the top of them if it is super dry up there..in order to have plants survive the very dry conditions, but use a lot of good quality mulch as well..and put some of that clay in that hugelbed..but mix it in well with the other things in there..the clay will help it to hold some moisture.

you can also grow SOME DWARF fruit trees in pots on the property..use the largest types of pots you can find..and remove the bottoms of them for drainage and for roots to get out if they can..and put ina good amount of good soil and then add your tree and soil up to the top..

lots of vegetables and whatnot can also be planted in containers..a container can be anything..but you'll still have a problem with the drought..so you'll have to water or provide some moisture holding particulate in the fillling of the pots..use a mix of some of the clay that is already in your soil with the fill..use a dripper or soaker hose if you can? hope this helps
 
Angelika Maier
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Location: cool climate, Blue Mountains, Australia
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I realized that the fruit trees I planted directly in our soil/fill did in most cases better than those on the hills.
We have half a acre of fill, everything.
 
julian kirby
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Angelika, Plant Deep Rooted annuals like alfalfa, their roots may pull some of the debris up (I find rocks in my uncles raised bed every year and we double dig it every year), and I have read anecdotal evidence that it will grow into rock. or you could innoculate the alfalfa with mycorhizzal fungi so that there will be plenty of exudes digesting your clay/rock/dirt. inoculate as many different plants as you can with nitrogen fixing bacteria as well. Getting large amounts of organic matter into your clay is one of the best way to increase water retention. Grow plants that produce massive amounts of biomass off of your lowest quality spot, with the least amount of water needed, cut it down and either compost it or mulch it in where needed.

Do you have a worm bin? if you do spread a small amount of castings and a layer of green waste underneath your 1st layer of sheet mulch, the castings when wet release an exude that attracts other worms, kind of like an endorsement for your menu. If you don't already collect the rain water from your gutters in rain barrels, do so if you can. I have got a few rubber totes I set out on our drive way to collect rain water, I store them in the garage till needed.

Cover crops are important to keeping the soil moist.
 
Brenda Groth
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some plants LIKE rubble..the peach family seems to be one of those which might include the nectarine, plum, and cherry trees as well..but I would still make sure there is enough soil for some root ball
 
Shawn Aune
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Brenda Groth wrote:some plants LIKE rubble..the peach family seems to be one of those which might include the nectarine, plum, and cherry trees as well..but I would still make sure there is enough soil for some root ball


Agreed! One such plant is Mullein
 
Angelika Maier
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If peach like rubble that is good. Anyway I want to plant some in the chicken run they like chicken poo too.
 
Robert dicosta
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I would certainly dig over a week for just one bed and break several handels.
The huegelbeds did fine as long as the weather was very wet. But not it goes back to dry and they are a nearly complete failure.
 
wayne stephen
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Funny , I was just reading the JLHudson,Seedsman catalog. Quote regarding Milk Thistle { Silybum Marianum } "California ranchers claim it loosens hard , compacted soil , and make their own "clod buster" from chopped plants soaked in 55gallon drums of water." He sells for $2.00 - 100 to 500 seeds. Thistles will grow anywhere. They are dynamic accumulators , can be sold as medicine , are good eating - stalks taste like artichoke.
 
dj niels
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Location: CO; semi-arid: 10-12"; 6000 ft
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Angelika, when you say "cool" I'm not sure exactly what you mean by cool; when I lived in Maine, and in western Washington, they were both cool, but different. Anyway, in Maine my sheet mulches didn't work very well because the summers were so short, and the permanent mulch kept the soil from warming up until almost too late to get a crop.

When we lived in Delaware, my small garden was built almost entirely with the grass clippings I collected from neighbors, and it was very productive for a tiny space, but you need to be careful about herbicides used on many lawns, in the "weed and feed" a lot of people use.

A sheet mulch does a good job of catching and holding moisture from heavy rains, into the dry season, but sometimes prevents light rains from getting through to the soil and plants. Here in Colorado I find I need to run a soaker hose under the mulch so I can get water to the plant roots, but as my soil improves I hope to be able to do less watering and hold the moisture from the fall, winter, and spring rain and snow (most of our precipitation comes in the "off-season"). After some experimentation, I have noticed that the beds we dug out deeper and have the mulch layers sunken instead of raised, seem to do better in my dry climate, but if in an area with lots of rain that might not be as desired.

My back yard has a heavy clay soil. When we first moved here 6 years ago, I raked off the gravel a previous owner had spread over the yard, and just put down sheet mulches and lasagna beds. Two years ago when we needed to move the beds, I lifted off the beautiful soil we had created with the sheet mulches, and the ground underneath is still hard-packed clay. My sons had to work hard with picks to loosen the soil so we could dig out our new partially sunken greenhouse. In fact, even in our sandy soil at my market garden site, there is a compacted layer that requires the pick and shovel routine. I know it can be very frustrating to look at our individual situations and try to figure out how to turn a "problem" into a 'solution."

The hugel beds will probably work well for you, but based on my reading in this forum, and the videos, etc, you may need to use a soaker or drip system in the first couple of years until the wood starts to rot down and hold moisture for your plants. And it might take a couple of seasons with pioneers and cover crops and nitrogen fixers etc to build up the soil so it can support trees.

djn
 
Rick Valley
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So without answering anyone in particular, here's some of my experiences- Digging into rubble, especially of a burn, could be exposing heavy metals in active forms. I'd build soil on top. sheet mulch varies tremendously. If you want the mess to heat up more, make a broader seeding zone, even if some of it is very shallow, so it is helpful in heating up. Crushed charcoal can help darken the area. Mound beds won't dry out if they have good clay content in the soil which is well-distributed in the mound. (I eschew verbosity- why say "hoogle" if the one-syllable "mound" says the same thing? You can certainly use wood in a sheet mulch, too. Don't neglect to plant good N-fixers in your mounds to help get the wood decaying.
Compacted clay will pool water- if you contour it and make sure the low areas are well-compacted, you'll have interesting water patterns to play with. Burying wood deeply before sheet mulching can also have nice effects, such as deeper rooting & better water reserves.
 
Marco Banks
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The best remedy for any sort of compacted soil (clay or otherwise) is mulch, mulch, mulch, mulch, mulch and moisture.

The forest service has found that the best way to decompact service roads in order to plant trees is simply to pile on organic matter on the roads and to leave them alone.

Organic mulch and moisture will get all sorts of good things happening, most significantly earth worms and fungi. If you build it, they will come. Wood chips are fantastic for this, easy to transport, easy to spread, and for most people, readily available. You'd be shocked how quickly an 18 inch layer of wood chips breaks down if there is rain or irrigation to keep them moist.

After a year or two, the soil should be soft enough to begin planting some deep rooted cover crops to punch through the compaction and pull the fungi and bacteria down into the soil profile.

We had a little path to the back of our lot where a boat had been parked and it had been driven on by a truck for years. Apparently, they'd driven on it while it was wet because the ruts on that road were 5 inches deep in places. Within 2 years of mulching with wood chips and planting cover crops, you couldn't tell that there had once been tire ruts, and the garden plants we planted the next summer did fantastic there. Now that whole space has fruit trees thriving, and I can easily dig down a foot with my bare fingers (Yeah, I know . . . half of that depth would probably be decomposed wood chips, but still . . .).

Clay is the basis tremendously fertile soil, but you've got to have organic matter being incorporated down into it if you want the plant roots to access all the nutrition that bond with the clay particles. So mulch, mulch, mulch, mulch, mulch.

 
Daron Williams
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Been going back and forth on how to deal with the clay on my property. My initial idea was fairly labor intensive (required a lot of cardboard) so now I'm trying to think of a better option and I would appreciate any feedback. I just got a scythe and have been practicing using it and so far that is going great. This is resulting in a large amount of thick grass cuttings that I have already been placing around some willow live stakes to protect them from the heat. I also found out that I can likely get one and perhaps more dump truck loads of leaves brought to my place this fall. With the scythe I'm planning on starting to cut my fields 2 times a year (spring and fall). So what I'm thinking is that I would pick out the area I want to mulch and then place the grass cuttings from the fall over that area. This would be really thick and would make a decent mulch layer. Then I would place a large amount of leaves on top of the grass cuttings. I might then followup with woody debris and wood chips on top of the leaves depending on the area and what my long term plans are for it. My thought is that the combination of grass cuttings and leaves could let me avoid cardboard or newspaper which would save me a lot of time and energy collecting it all and then pulling tape off the cardboard. I have over 2 acres of fields that I can harvest material from and a dump truck load of leaves can cover a large area. My thought is that the mulch layer would be upwards of a foot thick when fresh and would then shrink overtime as it settles and breaks down.

To summarize I would place thick cut grass/hay down at least 6 inches thick and potentially upwards of a foot thick while fresh. Then I would add several inches of fall leaves on top of that with some woody debris and/or wood chips as the final layer.

What do you all think? Would this be an effective sheet mulching strategy for covering existing grass and other plants (vetch, n such)? I know it will improve the soil regardless but I want to be able to go in and plant in the mulched area the following year or potentially the year after that.

Thanks all!
 
Todd Parr
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Daron, if it were me, I would only put the grass an inch or so, and then, leaves, and then more grass, and then more leaves...  If you pile grass too thick, it turns in to a slimy, stinky mess that is pretty awful.  I've done it, and won't do it again.  If you layer it with the leaves or wood chips, it won't do that and will break down into really great soil.  If it's hay rather than actual grass, you can go deeper without problems.  I have used pretty thick layers of hay without the same issues, and you're right, if you pile it thick enough, you can do without the cardboard, especially if you have a nice thick layer of wood chips for the top layer.  Just be sure to always have enough brown mixed in with your greens so it doesn't go anaerobic.
 
Daron Williams
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Thanks for the advice! I will give it a go doing the alternating layers and mixing in some woody material. I'm not sure if I will have enough woody material but I can at least alternate grass cuttings and leaves.

Would you recommend starting with leaves or grass? Since I will be placing it on top of living grass I was thinking it might be best to start with the leaves and then add the cut grass and go from there.

What do you think is a minimum for the thickness of the mulch when fresh?

Thanks again!
 
Todd Parr
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Daron Williams wrote:Thanks for the advice! I will give it a go doing the alternating layers and mixing in some woody material. I'm not sure if I will have enough woody material but I can at least alternate grass cuttings and leaves.

Would you recommend starting with leaves or grass? Since I will be placing it on top of living grass I was thinking it might be best to start with the leaves and then add the cut grass and go from there.

What do you think is a minimum for the thickness of the mulch when fresh?

Thanks again!


I would probably start with leaves as well, but in practice, it probably won't matter.  The minimum thickness really depends on what is growing there already.  If it's something like quack grass, you have to go really deep to kill it, and even then it can often grow up through.  When that happens, I usually pull it out as well as I can and pile more stuff on.  If it still comes through, then I use cardboard and pile stuff on again.  If you are just trying to break up your clay and build the soil, 6" or 8" works well, but the deeper the better.  Given the choice between doing a 200 sq ft area with 4" or a 100 sq ft area with 8", I would go with the 8" on the smaller area.
 
Grace Gierucki
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Location: Southern Michigan
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We have clay soil here, although it's not ultra heavy and no rubble. I'm no expert but I can tell you that last year I used 3 year old wood chips (the kind the tree trimmers deliver free and it just sat exposed in the field) to hill up potatoes.  After the season I dug it in a bit, maybe the top 6 inches and that is BY FAR the nicest area in my garden.  Once it was spread out over the whole bed I would guess it was only 2" of mulch but wow has it lightened up the soil. If it was me I would use an out of the way spot to collect as much soil building material as I could and then let it sit.  If your aren't in a hurry to plant in some spots you can certainly mulch in place.
 
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