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I intend to propagate trees and distribute them in bare root form after they grow for 1-3 years. Lots of good info on that process is available at https://depts.washington.edu/propplnt/Chapters/Bare%20Root%20Chapter.htm

The location I have for this project is generally clay soil. I've yet to do a thorough soil analysis so that will help inform what amendments are needed, but I already know from observation that the soil is generally heavy clay. It does not become inundated except in heavy rains, but it is heavy soil and can flood in storms. I know I'll want looser, better-drained soil for rows of trees growing for eventual bare-root transplanting.

How can I amend this clay soil to make it better suited for bare root tree propagation? I imagine I need to make it looser and better-drained.

I envision tilling the existing soil a few feet down, then adding plenty of organic matter year-after-year on top of that to build up better soil. However, I generally think of no-till as being good so I wonder if that can be avoided (minimal till seems necessary in this case), and I wonder if I should refine my idea about adding organic matter. For example, should I add fiberous structural material like coconut husk fluff piled on top of existing clay? What role does mulch or fresher wood chips have in this if any?

  • What kind of trees are they? And, have you attempted growing any of the trees in it before? With what results? – Shule Apr 27 '18 at 20:59
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    @Shule They're a wide variety of mostly edible trees: black currants, hazelnuts, pear, apple, elderberry, willow, blueberry, raspberry, blackberry. I realize not all of these prefer the same conditions and some may require dedicated beds (like blueberry needing more acidic soil, or oaks needing a bed that facilitates air pruning of tap roots). I haven't attempted any trees in this soil yet. It could be that the best technique is to use the soil as is. I'd agree with that for trees staying on site but am less sure in cases where I plan to transplant the tree as a bare root specimen. – cr0 Apr 30 '18 at 18:25
  • That's great information for the answerers. FYI: Black currants and elderberries seem a lot more tolerant of the clay in our soil than things like blueberries, raspberries, and hazelnuts. Blackberries take a while to get established in our soil (which isn't pure clay), but they do fine once they've been there a few years. – Shule Apr 30 '18 at 18:39
  • The success of different species in clay is one thing, but does the fact that I'd hope to dig them up for transplant as bare root trees change their soil needs? @Shule – cr0 Apr 30 '18 at 18:46
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    I'm still working out the process but basically I envision starting seedlings/cuttings in these beds or in pots and then transplanting to the beds; growing rooted seedlings/cuttings out for 1-3 years; then digging up for transplant (I figured as bare root but stormy's answer has me considering ball & burlap more seriously). – cr0 Apr 30 '18 at 19:29
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Great question crO. I have to jump in an say CLAY is great soil. Period. You just have to learn to manage, Clay soil which is soil made of of: sand silt and clay sized particles. That is all soil is; tiny little rocks. Clay is the tiniest as well as flat which means electrostatic electromagnetic properties are heightened...Sand is the largest and has its own problems that are worse than clay. It is all about knowing your soil, knowing soil properties to be able to 'manage' the soil you already have.

The ONLY way to improve any soil type is the addition of DECOMPOSED organic matter. To the surface of a once dug, double dug, plant bed. The life in the soil, not the decomposers, need DECOMPOSED organic matter to eat for energy. Let's call it DOM, okay?

Trees are different than all other plants because they need to be planted in undisturbed soil...that is best for them to acclimate to the soil they will live with forever.

What I am disturbed about is you wanting to grow trees and then make them bare root. If you are growing in clay, you have the best soil to grow trees and be able to make them Balled and Burlapped. Clay keeps the root ball tight and smaller so nurseries can start the root ball sequestration that fills the root ball with feeder roots and prevents major stress in transplanting; to pots or left B&B in sawdust.

Bare root style nursery trees have to be very young, a whip only, dug during the first year or two during the dormant season and sold before the growing season.

Since you have clay, you should think about B&B, not bareroot. Far easier, you will have lots more time to sell and your trees will be more successful.

For clarity, you do not want to amend your soil to grow trees. Amending soil using...gravel, sand, gypsum, lime...all you'd need to do is add water and rotation and you will have concrete. DOM is the ONLY amendment to any soil any one should ever consider. Trees should be grown in undisturbed soils. All other plants I insist on making the planting bed by double digging (one time...). Not trees. Clay is perfect for growing trees as a product. Not amended one little bit.

And I have to point out that I disagree with this NO TILL fad. Bogus. Trees are different. You should consider growing your trees in buried pots of potting soil if you are set on bare root. B&B would give you an awful lot more flexibility. Those trees should be no more than a whip of 3 to 4', dug up during their dormancy only and sold before the next growing season.

This picture are my raised beds now going on 5 years all I do is clean out the trenches, throw that soil on top of the bed, rake, compress and plant. I just love this picture. The soil is unrecognizable from original...oh, I always fertilize after planting...according to specific plant needs. Balanced NPK. Always. Plants usually are getting their second shot of fertilizer when planted into the garden soil. My fertilizers have formulas in the single digits, never in double digits unless using Osmocote. Proper fertilization just enough not too much will produce a tree that is able to 'fight' disease and insect infestations.

There is always 1 to 2 weeks of acclimation for plants from artificial lighting to the light of the green house. 2 weeks minimum to acclimate to the raw sunshine. I have to cover the starts with reemay for a few nights to reduce the shock of temperature change from the 90's down to the 40's every day.

After planting DOM is dumped on the surface (AWAY from any bark) an inch or two to feed the soil organisms and smother weeds. If there are any.

my beds 2018 volcanic pumice with DOM

Growing baby trees this would be important to do. Planting your b&b or bareroot in the garden, you would only dig down to UNDISTURBED soil to plant a tree. No disturbed soil beneath the root ball of a tree. Bark stays out of the soil, mulch. Completely.

  • Thanks for the info @stormy. A couple of follow up questions: 1) could you expand on "so nurseries can start the root ball sequestration"? I'm not as familiar with B&B preparation, though I've planted a few trees that way, and am under the impression it is significantly harder to prep since nursery soil is lost, and units (trees for sale) are much heavier. 2) What do you mean by double digging? Regarding undisturbed soil, I did plant some trees in this soil that are intended to stay there permanently. In doing so I dug out a hole for the tree and filled it back in, gently compacting as I went. – cr0 Apr 30 '18 at 18:31
  • A tree has to have x amount of roots to support the topgrowth. Clay keeps the roots together and holds onto moisture better. Sequestering roots means growing the roots within a manageable root ball size. Clay is also heavy, I never stake B$B. I do stake bareroot trees if there is any foliage, for a few months. The only problem is when a clay root ball is planted in a sandy or silt soil. The water will run around the outside of the root ball never getting the clay wet again. PVC pipes with holes fix that problem nicely. – stormy Apr 30 '18 at 20:02
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    Some nurseries grow their trees in the field and start trenching the proper sized root ball for; inch caliper, 1 1/2 inch caliper, 2 inch caliper trees, fill the trench with straw until the tree has reached the caliper desired then popped out, wrapped in burlap infused with copper sulfide to inhibit root growth through the burlap. Larger calipers get a metal frame around the root ball before being burlaped. These trees are then placed in thick sawdust beds until they are sold and transported away. You have to go check out some nurseries...not retail, wholesale. – stormy Apr 30 '18 at 20:12
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    They will tell you who their growers are. They might grow a lot of their own plants but always procure plants, such as bare root, to round out their stock in wholesale to landscrapers, contractors anyone with a resale card. Bare root is a season perishable. B&B a longer term perishable. Years long. Once you have a client base, growing bare root might become feasible. When you plant B&B, you only disturb the soil to the depth of the root ball no more. Disturbed soil will settle and the kiss of death to trees and other woody perennials is being planted a little too deep. – stormy Apr 30 '18 at 20:20
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    Then I rake it to a flat top, get a chunk of plywood, thicker the better, throw it on top and start jumping up and down to compress big air pockets. Then I dig the trenches all around the base of the bed, throwing that soil on top of the bed, raking and compressing again. Learn how to flip soil using a rake from the sides up onto the top of the bed (great for covering seed). While I make this bed I am throwing DECOMPOSED organic matter by shovel fulls into the pile of soil. 2 cu. ft. per a 10X3' row? My beds are 3' to 6' wide not including the little trenches. Cover crop for winter. – stormy Apr 30 '18 at 20:39
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Investigate the use of gypsum as a soil amendment.

Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4•2H 2O.

Gypsum is often known as a “clay breaker” but in fact it does the opposite - it binds the tiny clay soil particles together to form clumps, thereby greatly improving water penetration and drainage. The calcium in gypsum also helps to “sweeten” (make less acidic) clay soils that are often acidic. A soil ph test kit can be purchased cheaply and may help you decide whether to add extra lime (calcium carbonate) to balance soil pH.

Generally spread gypsum at a rate of 2 pounds per square yard / 1 kilogram per square metre.

It may be worth obtaining some professional advice on the application rate however - this relatively minor cost could save you many hundreds of hours work. It could also make a large difference in the growth rate of your plants.

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