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Amending clay soil for vegetable garden and fruit trees/shrubs

 
sarah preisner
Posts: 6
Location: Zone 5B
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Hi all,
I am new to this forum and am approaching my second year in implementing permaculture techniques in my garden. A little background first. I live in a typical suburb neighborhood in zone 5 (michigan), and have pretty much solid clay soil. I also sit at the bottom of sloped yards, so my yard gets all of my neighbors rainwater (great unless it is extremely slow to drain like mine). I wanted to only do a no til approach to my garden as I knew the existing soil was not good enough to plant in. So I laid cardboard down and put organic matter (including leaves, compost, horse manure, straw, and top soil) in place for my garden beds, and wood chips down for pathways. My garden area seems to suffer, I am thinking the beds are not deep enough? I have really struggled with my fruit trees and bushes. I have apple trees, pear trees, peach trees, cherry trees, blueberries, raspberries, grapes and black berries planted. All fruit plants were planted within the last couple of years. When planting I mixed in some compost with my soil, but that was it. I've noticed a lot of the leaves turn a somewhat red color throughout the entire growing season (low oxygen?), and have not been able to get raspberries established for the life of me. I concluded that I needed to get my soil tested, so last fall I finally did.

Here is what resulted:
"Soil is hard and clumpy - needs conditioning - slow to drain. PH 6.6, Hummus 1 (very low), N 60#/A (low-mod), P 75#/A (low-mod), K 140#/A (low)"

They provided some recommendations on what to do to amend the soil, and I have some ideas, but am curious any one else's experience/recommendations. Help please!
Thank you!

Here is an aerial photo of my garden space for reference.
Screenshot 2015-02-24 at 3.34.20 PM.png
[Thumbnail for Screenshot 2015-02-24 at 3.34.20 PM.png]
Aerial Garden View
 
Geoff Kegs
Posts: 30
Location: Northern lower Michigan
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Hi Sarah,

Clay varies in our state significantly in a number of ways and is more or less permeable. If you have impermeable clay you may have to design some way for the soil to drain, (mini swales could be good for this for sure, dug by hand - using a pick axe) and/or you'll have to build a soil above the clay which will require some sand, humus and minerals. Many of the minerals are already in the clay, so what I would do is swale it (shaping the hillside as to slow the water moving down slope by running it along long contours of the hill) first, then add some clean sand and composted chicken manure to the clay, then broadfork it in, and plant it with a "permaculture blend" seed mix, innoculate the soil and start composting if you can (not sure if you raise chickens, but that is a very good asset to use to help you with your soil conditioning chores!) I'd use some cobble and gravel for the overflows and design it carefully

Ideally, you should consider a full spectrum soil test conducted in a lab - the one you got only tests the macronutrients, but there are many more important minerals and nutrients to test for. The tests cost about $50. You should mineralize your soil as necessary to ensure the plants you are growing can make the best of the soil. Soil biota is every bit as important as the minerals to ensure harmony in the soil (harmony in my mind means dark, rich humus). Once you build the soil and maintain it properly, it will work well for you for a long period of time.

Welcome to permies!

I myself haven't been on here for a while, but its an incredible community for knowledge. I hope others chime in as well.

Best,
Kegs

 
Alder Burns
pollinator
Posts: 1341
Location: northern California
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One key point I've learned the hard way more than once: never dig a hole into clay, with a view to planting a permanent plant, especially a fruit or nut tree, and then add amendments of any sort, including organic matter, into the hole around the roots. This backfill will be inevitably looser than the surrounding clay, and in wet conditions all the air space will fill with water. Since the surrounding compacted clay is so slow to absorb and drain, you've basically put the plant in a pot full of water. If this happens in the growing season it will drown in a couple of days! So the takeaway is....for more tolerant plants, plant directly into the unamended clay, tamping it well, so that the soil structure quickly resembles the undisturbed soil. Apply amendments as a mulch, or if they are nasty (like humanure) in a hole beside the hole for the roots. For sensitive plants (and most fruit trees especially fall into this category, with berries being a possible exception), plant them on mounds or raised beds of some sort, whether of improved or unimproved soil. These may settle with time, but established trees will have enough roots wandering in the general surface soil to tolerate waterlogging better. If the area floods for more than a day at a time, though, especially in the summer, you need to be planting just about everything on beds kept above that saturation level......
 
Marianne Cicala
gardener
Posts: 660
Location: south central VA 7B
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Hi Sarah
In VA, we have terrible clay also. I always plant trees, bushes etc proud - for a fairly big fruit tree (5-6' tall and 1" caliper or better) I leave the root ball almost 4" above ground level, berries about 2". You'll have root rot otherwise. You may even consider putting some gravel in the bottom of the hole (only about an inch or 2) then mix dirt, compost and native soil and fill. I would strongly suggest doing a sheet mulch (at least 8 pages of newspaper thick) around the tree going out as much as 5' in all directions, cover with the dirt, compost, clay mixture and them cover that with straw or wood chips. I leave that for about 6 months, usually spring and summer months, then I'd begin to add companions, bulbs, yarrow, coreopsis, lavender, comfrey etc. Next spring add more plantings including berries. Good luck - it looks like a great layout!
M
 
alex Keenan
Posts: 487
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I can tell you what I found from some tests I did that were published and some studies done on soil compaction.
The key is pore space in the soil.
If you add organics to permanent crops the soil tends to revert back to the soil profile it was before over the years.
You have leaf litter layer on top, than organic declining until you hit subsoil.
I was working with host under maples in silt/clay soil.
If you put iron rods in the soil you will get red rust and black iron on the rods.
The black iron is where soil went anaerobic. Roots need oxygen and they tend to die without it.
Many times oxygen is the limiting factor in how far roots can go.
Also a root tip grows into a opening and expands. So there has to be a minimum pore space for the root tip to grow into.
What I found is if I added non-organic materials to the subsoil areas that are lower in organics I tend to create Macro and Meso pore spaces for the long run.
Once these are created roots will grow into them providing organics and allowing water storage and oxygen flushing as water fills pore space and drains away.
I worked with expanded shale, perlite, porous sand, non-toxic bottom ash, broken bricks, pottery, etc. The key was working with a porous material that is non-toxic and does not break down.
I also found that carbon as in bio char tended to last reasonably well.
If you double dig and add this type of material to clay at 20 to 30 percent you should get good results.
Also by adding this to the clay instead of organic material you do not get wicking action you can get with high organic content. So you do not get the pond effect that kills roots.
Also organic material mixed in soil decays. Sometimes the rate of decay is very fast. The non-organic material will not decay.
So once you have subsoil and soil porosity ok you can mulch and let soil critters do their stuff and have your different concentrations of organics that will develop stable levels within your soil over time.

My two cents worth
 
sarah preisner
Posts: 6
Location: Zone 5B
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Thank you all for your suggestions! Sounds like I should be focusing on building some swales in areas that collect water the most, would filling them with gravel and woodchips be the best approach, maybe even some broken pots or other inorganic material? My thought with the garden beds was to double dig them and amend the soil and then top dress them with some fresh compost. I had recently heard about the expanded shale, and to hear that suggestion from someone else is encouraging! I think I will go that route and add it to the soil with all of my new plantings as well.

My question then is regarding my existing trees and shrubs. Should I attempt to dig them up as best as possible and add inorganic material to the soil and raise them up above the soil by a few inches? Followed by adding mulch around them? They are very small so I'm not too concerned about damaging them. Should I also add any fertilizer to the soil as I add the expanded shale or other inorganic material to make up for the lack of nutrients in the soil? The soil results suggested adding a 12-12-12 fertilizer, and as I'm not familiar with fertilizer at all I have no idea where to start, any good organic brands? Do I top dress or add it directly to the planting hole?

Thank you again for all of the suggestions, I am learning more and more every day!
 
alex Keenan
Posts: 487
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If you are adding 12-12-12 think about how soluble it is.
Adding a highly soluble material to soil will likely leach out quickly.
If it is things like bone meal, feather meal, etc. things that break done over time than you get long term results.
As for where to added it.
In a natural setting everything makes it to the leaf litter.
The worms and other ground critters move it around and decay it.
The solubles work their way into the soil and are taken in by the roots.
So for me the key has always been creating a living layer of 12-12-12 by feeding the microbes and critters.
Goal should be to create soil sturcture that will support soil life.
Once you have the right starting structure you feed the soil life.
Soil life will increase good soil structure and recycle nutrients.
Normal decay from recycling will feed your plants.
Just add organics to supply 12-12-12 as soil life builds.
Make sure you create a nice leaf litter layer after you plant. Some leaf mulch, a little bone meal, some wood ash, etc.
 
sarah preisner
Posts: 6
Location: Zone 5B
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Ok, I've been searching and searching but cannot seem to find a local source for expanded shale in large quantities. Suggestions on sources? Other materials that might work? Gravel or crushed concrete? Would fill sand equal coarse sand? What about lava rock?
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