To amend or not to amend? Clay soil...

thaprankstaFebruary 29, 2012

I'm getting ready to start my first venture in fruit tree planting in a couple of weeks. I've gone with what I think is a healthy mix of responsibilities for the beginner gardener. I've got a Shiro plum, a Satsuma plum, a Redhaven peach, and a Shinseiki pear tree. I definitely appreciate the plum advice I received on this forum as it really helped me make my decision.

I understand that I have clay soil. I've seen conflicting advice on how to deal with it however. Some of the things I've read say don't amend and some say you should. Some say you should plant the tree so a little of the root is above the hole. Others make no distinction. I have no clear idea. If I had to make a choice at this point, I'd guess I shouldn't amend because it will be easier for the trees to adapt to the clay in the long run.

Does anyone have any good advice? Thanks.

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Much of what we have in the deep south isn't actually clay... The vast majority is some flavor of "Loam" - although everyone calls it "Red Clay"...

Before you declare it officially clay - do the Mayonnaise jar "Soil Structure Test"... 99% chance you will find it's not clay...


    Bookmark   February 29, 2012 at 9:36PM
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I say amend.
I dig a hole for ANY tree three time the dia.
I use to dig down deeper the root ball a few days before I plant & amend under the root ball, but I have been told NOT TO DIG DOWN. To put the root ball on unturned soil (solid soil). A tree will sink in new ground, but you can go out from the root ball as far as you like.
So make the hole the depth of the root ball, if you must go too low or high it is better to plant the tree above ground a little, then too deep, which will kill the tree over time.
But the right depth is best, the nursery can show you where
that is on a root ball.
In a pot the soil lever is the correct level.
The reason people say not to amend in the hole, is that you are forming a natural pot of amended soil.
Once the roots pass the "pot" the plant is let down by poorer soil.That is why I dick or till the whole bed & spread amendments over the whole bed.
I have read many things about the amanding not working, but I have never lose a tree to richly amended soil.
I have a 8 year old Moon Glow Pear & it is in a 6'x 12' bed
& it is doing great.

    Bookmark   February 29, 2012 at 10:11PM
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skyjs(z8 OR, USA)

I have lost a tree to NOT amending. Drowned in a puddle. I saw amend it to half way in between what you've got and the best possible soil for that plant. Dead plants don't grow out into the soil and make it their home. When I dig out my trees to move them, they are very happy.
John S

    Bookmark   March 1, 2012 at 2:16AM
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olpea(zone 6 KS)

"I have lost a tree to NOT amending. Drowned in a puddle."

John, I don't see how amending the soil would prevent a tree from drowning, unless you "amended" by installing a raised bed, which would be my recommendation for peaches planted in clay soils in areas of significant rainfall.

I don't amend and I don't spend a lot of time digging a big hole. When I first started I was more energetic and dug big holes, but now I dig the smallest hole possible. The trees do fine as long as they're mulched. If you want to size your new trees quickly, a steady supply of N will do it.

    Bookmark   March 1, 2012 at 10:02AM
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We all come from different areas. In Phoenix, our clay soil has virtually zero organic matter. As a result, we often amend our calcenous soil 50% in order to provide it. In other areas, amending is done primarily to increase drainage.

Your best bet is to talk to successful local gardeners and ask what they do or call your local state agriculture extension bureau and see what current recommendations are for your area.

    Bookmark   March 1, 2012 at 10:24AM
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olpea(zone 6 KS)

"In other areas, amending is done primarily to increase drainage."

Again, unless you plan to amend a large area, or amend by installing a raised bed, amending will not help drainage.

More often than not, beginners amend the small area of soil in the root zone effectively creating a "clay pot" in areas with clay soils. During heavy rains the clay pot becomes more water-logged than if the soil wasn't amended at all.

Here is a link that might be useful: Myth of soil amendments part II

    Bookmark   March 1, 2012 at 11:00AM
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shazaam(NC 7B)

I have heavy clay soil that stays very wet for most of the winter and early spring, and, for the reasons that olpea mentions above, I really like the raised mound/bed approach, especially for plants that like good drainage. Another benefit is that I can plant even when the soil is too wet to work.

    Bookmark   March 1, 2012 at 11:18AM
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alan haigh

All but the most porous soils we be better hosts for your trees if you create berns or raised beds for them- as long as enough roots are situated low enough to reach water during drought.

However, it's not enough to just say I have a clay soil and ask what should I do. You should test your soils drainage and if it's found severely wanting then the question can be answered much better.

I've had rich silts where drainage was terrible because of a sand subsoil and I've had black clay soils that look wonderful but during wet spells torture the trees.

Olpea's idea is probably the best way to deal with it labor-wise but it can also be advantageous IMO to create a sandy loam by mixing compost with sand about 50-50 and using it for the first 2-4" of top soil in about a 6-8' diameter circle for each tree. If this is done in addition to raising the planting area and mulching, you've got a place where at least part of the rootsystem can flourish at any given time no matter what the weather.

    Bookmark   March 1, 2012 at 11:21AM
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Opea is correct, in clay soils plant the trees in raised beds. Amending the raised bed really depends on how bad the soil is. If the soil comes off your shovel in a solid chunk (ie clay), you will want to amend it so the roots can grow thru it (when its dry it is a rock), air and water can inflitrate it, and when it cracks, it will not break all the roots. Tilling in sand will greatly reduce the size of the cracks (alot of little cracks vs a few large ones), long term organic material (charcoal, compost) will help with the stickyness, certian clays will respond to gypsum (others won't) for improved drainage. Also put your Ph modifers in as you make the bed (lime or sulfur)

    Bookmark   March 1, 2012 at 12:15PM
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alan haigh

If you mix sand with clay the lit says you'd better be careful because it takes an awful lot of sand to amend clay and less than enough is said to make matters worse- unless you prefer cement to clay. In NY, cooperative extension recommends against adding sand to clay- ever, but if you add enough it will eventually help- it has to. I think if you go this route it only makes sense to amend the first 2-5". You can spread some of your roots of bare root trees into this.

I've had success using sand in combination with raised beds in a soil that was blue clay suitable for pottery (it was trucked to the property free of charge and the client thought it was top soil because it was brought from an excavation to flatten the top of a hill). I used 2 full wheel barrows of sand for each tree along with 4 wheel barrows of compost and spent a great deal of time trying to mix equal parts of that horrible clay into it. I'm not sure this was the best way to go, but the bearing age 2" caliber mixed fruit trees thrived. The peach trees took a while though.

It's a lot easier mixing sand with compost to create a thin layer of all new topsoil than trying to blend it into clay- most roto-hoes can't do it. Not even my fancy 10 HP Mainline.

    Bookmark   March 1, 2012 at 12:41PM
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I used to live in Giles Co; now located just across the state line, north of you, in Christian Co. KY. I have experience with your soil type.
I vote for no amendments in the planting hole, just put the native soil(minus the rocks) back in after you position your trees, water in, and mulch well.

    Bookmark   March 1, 2012 at 1:07PM
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blackrag(6A East PA)

5 years ago, much like yourself, I got "bit by the fruit bug". Enthused and energetic with plenty of "successful-gardening" experience, I dug 12 holes 3'deep x 3'wide, disposed of most of what came out of the holes in favor of amendments that I caringly thought at the time would be "great" for baby trees. Long story short, I "mysteriously" lost 8 of 12 trees to what I now believe was due to Olpea's description of a CLAY POT. The 1st growing season was fine as they leafed and grew, by end of the next spring, they were dead "sticks" due to wet feet or "rotting out".

Glutton for punishment, I am now at over 50 trees and 1/2 will begin their 3rd growing (and hopefully fruiting) season this spring. They all appear to be doing fine. I believe that this is due to digging a minimum hole, minimum amendment, keeping the planted height as high as I can, staking and mulching.

Going forward, I had also kept in mind slope and drainage as well. If you have areas that puddle after every rain, probably not a ideal spot for a young tree without dealing with that first.

Lastly, in the area I have these trees, not all the holes are totally clay, some have less clay content in appearance or weight of the shovel for what it's worth.

Good Luck,

    Bookmark   March 1, 2012 at 2:48PM
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I am going to say it again... 99% of people who say they have "Clay" soil don't.. They usually have 5-15% clay.... This is why it's important to do a simple soil structure test... Takes 3 minutes to prepare and a couple days to watch the layers settle out....

Yep - the reason they tell you not to dig big holes and fill them in with "Other" stuff is that you create hard pans... The small amount of actual "Clay" in most soils will percolate down through the disturbed soil and it forms a Clay Liner.... and a Clay Liner is how you make a pond hold water....

If you want to experiment with making a clay liner... dig a hole.... Pour in a whole bunch of water and stir stir stir stir stir stir... until it's all stirred up..... Then, let it sit...... Come back a day or 2 later and pour water in.... WOW - look at how it forms a puddle that never drains.... Yep - there's a thin layer of clay that formed a sheet that's waterproof....

Now.. There are amending practices that work... They mostly revolve around mixing in minerals that don't permeate soil particularly well - like Minor elements, Calcium, Magnesium, and Phosphate.... It can also help to mix in a teeny bit of mulch or organic matter... but usually - putting it on top is a much better idea in the end... It doesn't rot and leave a hole where there used to be dirt - and your tree falls over sideways... and it doesn't create a hardpan that makes a kiddie pool and prevents root growth...


    Bookmark   March 1, 2012 at 3:54PM
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I work for forest service as a tech and while a pine is not a fruit tree in the simplest explanation we create a slit in the ground, insert seedling to root collar, make sure roots are straight (random check by digging up a planted seedling), and squeeze closed the slit. Wait 20 years and harvest lumber.
Now even with this knowledge for pines I also know that our local soil is very nutrient poor as is most of the soil in the deep south. I therefore add some compost to my sandy soil when planting out fruit trees. Think of a boil of soup you want to add crackers to. Don't go crazy just add a little nutrients for flavor.
Oh and we have red 'clay' down here for sure. Do a squeeze test. Grab a handfull of soil. Add a little water. Does soil hold together when squeezed? If not sand. Yes but is somewhat crumbly then loam. If yes and you can make a tight ball that feels slick then clay. That is it in a nutshell.
The perk test works well too if you have patience as does the jar or water test noted above.
So with all of that mulch for sure, you can add just a touch of compost or bark or what have you you desired but native soil should be the bulk of what goes back in the hole.

    Bookmark   March 1, 2012 at 4:23PM
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alan haigh

When I talked about amending clay it was a blue subsoil in which nothing could grow- not typical southern red dirt. I would listen to those who have experience in that stuff. There's nothing around my area like that. Sounds like you've got some good ideas to work with. I don't think you should hesitate to grow the trees on raised ground, however, that will help the productivity in most soils with less than stellar drainage and is widely recommended for peach production- even in pretty good soil it improves productivity and longevity of the trees.

    Bookmark   March 1, 2012 at 6:50PM
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Right on.. I have seen the stuff you are talking about Hman, when I visited folks up north... It's worlds different from what folks call "Red Clay" - which is usually properly classified as some flavor of soil with Sure.... It's red and slimey when wet.. but it's almost never "Clay" If it was - our soils wouldn't have a Ceq of less than 5.... which is also pretty typical for bare scraped soil at a new homesite....

When the lady at the USDA office did the smoosh test on my dirt - she squished it out into a pencil shaped stick.. It crumbled pretty quick... where true "Clay" will hold together like a wet spaghetti noodle. If it's clay - you can tie it in knots and it won't crumble....


    Bookmark   March 1, 2012 at 7:42PM
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Yeah, there are some pretty good ideas. I'm going to try the mayonnaise jar test to get a more accurate assumption of what I've got. I assumed that since I was told it was clay (even by the local extension office), it is red in color, and that puddles and wetness lingered after a rain storm that it was indeed a high percentage clay.

After going out back and really picking up some of the wet soil, I noticed that while a lot of it retained its shape when squeezed together there was quite a bit that crumbled in a "loom"-like fashion. I think John has made a pretty fair assessment.

Lucky is definitely local and has an interesting suggestion with the basic "just plant it" approach.

It seems that it is highly recommended to plant peach trees in raised beds from the experience on this board. Does anyone have a good link or more detailed directions as far as how to do that? What type of soil do I need? How deep do I dig the hole? How high should the bed be?

    Bookmark   March 2, 2012 at 11:12AM
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fruitnut Z7 4500ft SW TX

It doesn't matter if it's clay or not the important factor is how well it drains. Dig a hole, fill it with water, let it drain, and repeat. If water stands in the hole a long time the second time around you've got issues. Clay soils can drain pretty well if they have good structure.

Red soil is nearly always well drained. It's red because the iron is oxidized to a rusty color. Grey soil indicates poor drainage. Subsoil color is more important than topsoil. And topsoil color is more influenced by organic matter.

Soils that are bad for fruit trees usually have a high water table at least part of the year. High being above 24-36 inches depending on soil texture and water permeability.

    Bookmark   March 2, 2012 at 12:00PM
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olpea(zone 6 KS)

"It seems that it is highly recommended to plant peach trees in raised beds from the experience on this board. Does anyone have a good link or more detailed directions as far as how to do that? What type of soil do I need? How deep do I dig the hole? How high should the bed be?"

For my peach trees I use mounds and terraces. It doesn't seem to make a difference how tall the mound is. Some of my mounds are 1' tall, others started out 4' tall (before settling). The peach trees do about the same either way. Some people enclose their raised beds with a raised border of some kind. I think that's fine too.

I don't think it makes much difference what soil you use for the raised beds/mounds. Several years ago, I installed drain tiles in the orchard area (The drainage was horrid and I was tired of losing peach trees.) In places we had to excavate to a depth of 4' to install the tile. What we dug out was pure clay. I used this material for some of the mounds. The peach trees have done fine in the clay mounds.

Per the above posts, I would only use mounds if the drainage is poor. But since you mention puddling, I strongly suspect you could benefit from raised beds/mounds. Mounds not only provide good drainage, they also loosen the dirt so there is minimal resistance for the roots to spread. Mulching on top keeps the soil moist longer into the growing season, further encouraging root growth.

It's hard for peaches not to succeed when they have moist (but not overly wet) loose soil with no weed competition and plenty of sunshine.

Here's a picture that's a couple years old. You can see some tall and shorter mounds. Some of the older trees aren't in mounds. The drainage tile helped them.

Here's a pic of some terraces I built last fall for planting peaches this spring.

By the way, I don't bother with mounds for more water tolerant trees like apple, pear and plum, unless the drainage is really bad.

    Bookmark   March 3, 2012 at 1:26AM
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alan haigh

I believe Rutgers has done research on this so you might try searching their information. Unlike Olpea's method, which obviously works well, they recommend raising the entire row- the soil is taken from the middles and, as I recall, about a one foot difference in elevation is created. In a traditional 20' spacing between trees of different rows that would mean scraping about 6" of soil from the middles. In traditional spacing, the trees in the rows would be about 12' apart.

I use a method similar to Olpeas and have used it for fruit trees for over 20 years. I discovered it in my wild days well before that, growing cannibas in marsh land. No internet back then.

    Bookmark   March 3, 2012 at 5:36AM
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ozzz(5b AZ)

Someone mentioned adding a steady supply of N to put size on trees ... what kind of materials would you guys recommend for this? Blood meal? Composts??

    Bookmark   April 2, 2012 at 4:09PM
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olpea(zone 6 KS)

"Someone mentioned adding a steady supply of N to put size on trees ... what kind of materials would you guys recommend for this?"


That was my comment. I used to use wet grass clippings to mulch new trees. Once a week, I'd collect bagged grass from the city. I'd fill the bed of my truck full of bagged grass. If I had to go into town twice, sometimes I'd get two loads. I memorized what day was "trash day" for various neighborhoods. I also learned which neighborhoods and which houses regularly set out the most grass clippings.

In a given season, I'd put literally hundreds of bags of grass on an orchard of 60-70 trees.

I also put a sign up out front indicating I wanted grass clippings.

The grass was easy to apply. Just open a bag and dump. New trees take off like a rocket.

There are some disadvantages to this method.

1. The grass stinks for a little while.
2. The grass gets so hot it will cook the trunk if it touches it.
3. Don't use it if your drainage is poor and you don't have your trees in mounds. Lots of grass clippings will make poor drainage worse.
4. Don't use it on mature trees. It's too much N for the fruit.

Some people worry about herbicides in grass clippings. I never noticed a single problem with my trees. Once I think I had some herbicide damage from grass clippings on tomatoes, but tomatoes are much more sensitive to herbicides.

I don't get pickup loads of grass anymore and I took my sign down in front of our house. I still occasionally get a lawn service that brings twenty bags or so of grass, but for the most part, I don't mulch with grass clippings anymore. They go away too fast. I try to use wood chips which have more longevity.

    Bookmark   April 3, 2012 at 5:13PM
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