How can I improve my compacted soil - without digging?

I have dozens of fruit trees planted and doing moderately well. They are in compacted clay-ish soil (not clay, but clay-ish). It floods around them twice annually - though I have the trees raised 10-12" in little planter boxes, to keep the root ball above water levels.

I have cow manure, chicken manure, and woodchips (Unfortunately, woodchips do tend to get washed away by the flooding, except on the raised planter boxes).

Grass grows around the trees regularly, which I mow and leave the mowed grass in place.

How should I improve the compacted clay-esqe soil immediately around each tree (on the ground outside the planter boxes)?

Just spread manure and woodchips?
What about pelleted gypsum - should I spread ALOT of it around the trees (2 ft from the tree), or be more cautious with it due to the nearby trees?
What about planting hundreds of daikon radishes in a circle around each tree (several feet away) - Is this a good idea in my situation or no?

What cover crops should I perhaps mix in with the grass that already grows there? (I think the current grass is a type of brome grass, but there's several other grasses and even a type of wildflower that volunteer there too)

The trees are mostly apples and pears and peaches - I'm not sure if that'd change your suggested cover crops.

What other suggestions would help loosen or otherwise improve soil without me digging?

So your trees are all in containers sitting in a low lying area?
The reason I'm asking is you say they are in little planter boxes but you want to mulch the soil around the containers?

If the trees are in containers to keep them from the water of the semi-annual flooding, there is no need to treat the soil around the containers.
The soil in the containers is where the roots are living, so what is under them could be concrete, gravel, grass, it just doesn't matter to the tree roots since they are inside the container.

It would seem that I need some more explanation before I can give good recommendations.


Redhawk

Could you define "digging"?  Broadforking may or may not be something you considering digging, but it's a great way to get some amendments down to break up your clayish soil.

Trace Oswald wrote:Could you define "digging"?  Broadforking may or may not be something you considering digging, but it's a great way to get some amendments down to break up your clayish soil.

Digging is using tractors or deep earth-diggers. The trees are close together (8-10 ft, sometimes farther), so not much maneuverability for larger vehicles, also I have irrigation lines buried that some digging in bulk wouldn't be able to avoid.

Digging also includes me going around with a shovel around each tree. Too many trees for me to manually dig through clay-esqe soil - I have limited time to devote to it. I mean, I could just dig three or four every month or so when the ground is thawed, for two years.

Broadforking sounds like a good idea - I've seen a video of that tool once before, but forgot those existed. That would enable me to avoid the irrigation lines easily (though I might accidentally snag one or two, that's an easy repair), and seems like alot less labor than shoveling. I don't know how easy it digs through clay-esqe soil with deep grass roots, but picking up one of those would likely be also useful in my vegetable garden.

Jamin Grey wrote:I don't know how easy it digs through clay-esqe soil with deep grass roots,

That's what I use mine for.  Obviously the first couple times are more work, but if you use it more often than once in a spot, it gets easier each time.  I rarely do any area more than once though.  It's pretty pleasant work.

Bryant RedHawk wrote:So your trees are all in containers sitting in a low lying area?

Yea, a failure of studying the land before planting, and then stubbornly persisting afterward. Huzzah!

The reason I'm asking is you say they are in little planter boxes but you want to mulch the soil around the containers?

If the trees are in containers to keep them from the water of the semi-annual flooding, there is no need to treat the soil around the containers.
The soil in the containers is where the roots are living, so what is under them could be concrete, gravel, grass, it just doesn't matter to the tree roots since they are inside the container.

They are just 2x10 or 2x12 boards screwed together in a 2½ x 2½ ft square, with no bottom. They are rested on the ground, and I prepped the soil maybe 18" underneath the boxes and the box soil itself, when planting the trees. My assumption/hope is that the transport roots of the trees will eventually find their way down to ground level, and then out horizontally from there.

The soil immediately within the boxes is good, and mulched. The soil immediately underneath the boxes is good. Under most the trees, deep in the hole I set the boxes over, I'd bury whatever I had available: dead fish, chicken intestines, aged cow manure, chicken bones, grass cuttings, coffee grounds, etc... (Only thing I wished I remembered to bury would be maybe old nails or something). I also tossed in some gypsum in later ones.

I mixed the native soil with some compost soil (and a little coconut fiber I had available), so it's not a huge shock transition to the clay-esqe native soil, but the biggest difference is compaction: inside and underneath the box the soil was loosened when I planted (though no-doubt the floodings have re-compacted some of it), but everywhere else around the box the soil is compacted.

I got maybe 30 boxes like this, and an additional 10 trees planted without boxes (above the flood area). I'm trying to figure out how I can begin improving the soil, for when the roots eventually reach the regions outside the boxes. 'Improve' meaning both loosening the soil, and supplementing it.

We're talking fruit trees like peaches, apples, pears, and plums. The trees are only a few years old.

(Eventually, ten years from now, the trees might burst the boxes. That's fine by me. If they start to burst them, I'll unscrew the boxes and remove them, or something)

Here's some diagrams:




Currently the trees are young enough the roots haven't reached much outside the boxes, so no worries harming existing roots by tilling or whatever. Here's how I'm hoping the roots eventually grow:

Trace Oswald wrote:That's what I use mine for.  Obviously the first couple times are more work, but if you use it more often than once in a spot, it gets easier each time. I rarely do any area more than once though.  It's pretty pleasant work.

I will definitely do this for aeration; and then supplement the soil with gypsum, manure, and wood-chips. Thank you very much for recommending it!
Maybe I'll even plant the diakon radishes there as well.


I'm absolutely interested in any other ideas people have!

Great diagram, thank you for drawing that, as it clears everything up. 🍎 worthy!

I'm a novice...that said...

My concern would be long term root-binding within the "improved hole" if the surrounding pink zone remains compacted.  With the flooding, I think the water, nutrients and looser soil would cause the roots to lazily circle around in their happy zone rather than branch out as desired, so good call taking action!

Broadfork sounds perfect. They're fun to use, in my opinion.  A little expensive, but they last forever, right?  

1)Maybe break up the soil of each tree in a 3 or 5 spoked-radial or star pattern  (rather than forking all the way within the pink circle area) in order to save broadforking time per plant.  

2)Broadfork all the way out to the desired drip line radius.  Don't let the spokes overlap between trees to avoid encouraging root competition.

3)Manure or compost and mulch each of the spokes, to further encourage the roots to grow along those lines.  Avoid walking on the mulched spokes by using any designated pathways.

4)Consider if the broadforking pattern could help channel or divert water to where you really want it to go.

5)Consider planting comfrey roots or other dynamic accumulators in between each of the star spokes for chop&drop.  Consider nitrogen-fixing ground covers or shrubs instead of the current tree-competing grasses.

Thanks, George Yacus: all of those sound like great ideas! I like the idea of using soil-improvement to guide root growth in desired directions.

I love tillage radish for leaves and seedpods,  but they haven't done much to decompact the clay soil I have.
I find the bulk of the root grows above ground, rather than down into it.
Maybe true diakon radishes do better?

I've been trying out an idea to improve water  infiltration in my yard that consists of driving wooden stakes into the soil and cutting them off flush with grade.

I've also tried using a bulb planting auger to create a hole to fill with carbonous material, but my 1/2" drill struggled against the wet clay.
After letting a little smoke out of the drills motor,  I tabled that idea.

A simple way to improve the tilth might be to expand the raised beds.
Carbon over soil brings worms,  and they improve tilt.
Expand the beds to 8 or 10 square feet, lay down card board and fill the new beds in with woodchips.
Plant comfrey in the wood chips and use it for chop and drop.

William Bronson wrote:A simple way to improve the tilth might be to expand the raised beds.
Carbon over soil brings worms,  and they improve tilt.
Expand the beds to 8 or 10 square feet, lay down card board and fill the new beds in with woodchips.

Yea, that's a method I used before. The city offers free well-composted grass clippings (potentially with lawn herbicides, but eh, I haven't had a problem with it yet), so in some areas in the past I've laid cardboard, covered with 3-4" of compost, and an inch or two of woodchips, and just leave it there for a year or two to absorb sun.

I may do that in some areas - though not where the rainwaters would wash it away. Expanding the beds would help, but also would cost money - about $40 a bed. Unless I build one expanded bed, and just move it from tree to tree every year, after grasses or w/e get established to lock the dirt in place - there's a thought worth thinking about!

Mulch and cover crops.  Rinse.  Repeat.

One of the principles of permaculture I appreciate most is utilizing biological resources to solve problems.  Yes, you can broad fork or double dig or utilize other physical resources, but I've found it easier to put down a thick layer of mulch and let the earthworms do the heavy lifting.  Wood chips are ideal for this.

Any cover crop will ultimately sink its roots into the soil and de-compact it.  Tillage radish, yes, but throw in both cool season and warm season grasses, as well as cool season and warm season broadleaf plants -- preferably nitrogen fixing broadleaf plants.

Best of luck.

Amen Marco!

I completely agree and couldn’t say it better.

Eric

Mulch with a foot or two of hay. If the weeds are tall, then wack them down first. If it's spring in your neck of the woods, throw some potatoes on the ground before you pile the mulch on and in the fall collect the harvest.

All that hay will break down and soil life will use it to decompact the clay. The first you you may gain 4 to 6 inches of soil. The next year a foot.  Keep on doing it until you have enough topsoil.

I like the mulch/woodchip idea. It sounds like the only real obstacle is them washing away in the floodwaters. How deep does it get? Can you divert or slow the water down so it doesn't carry them away? Would something like sunflower stalks be enough to hold mulch in place? Would you have to grow small bushes to do that? Currants might fit that bill here but I have no idea where you are. I had visions of more boards making sort of riffles to catch/trap mulch but I don't think that would work as well and would be too labor intensive. That said, if you had tree branches that would be heavy enough to not wash away it might work. Big rocks to slow the water? But I like the idea of using plants since they'll give you so many other inputs, too.
DK

It's just a time factor for me.  My absolute best areas for planting are areas where I put down a ton of wood chips and just left it alone.  That takes quite a bit of time to get really good though.  If I want to create a new garden this spring and get it up and productive quickly, I broad fork a lot of organic material in, put down compost, and then put down my mulch layer of wood chips.  I can create a planting area much more quickly that way for what I feel is an acceptable amount of work.  If I had trees that I was worried about drowning, I would broad fork as large an area as possible around them and get a bunch of organic material with biochar in the ground right away, and then mulch it.

Daniel Kaplan wrote:I like the mulch/woodchip idea. It sounds like the only real obstacle is them washing away in the floodwaters. How deep does it get? Can you divert or slow the water down so it doesn't carry them away?

Worst I've seen is about 10 inches, with moderately strong flow. The waters only stay 10" for the first two days, and fall to 6" or so after 48 hours, and 1" after 72. They've lifted up and moved logs. In some of the tree's ""planter boxes"", the floodwaters would erode the dirt from under the boxes. I've solved that a few years back by putting a little concrete at the front of the boxes, facing the oncoming currents.

I can't really divert most of it - but I could box of some areas to keep some areas less floody. One thing that's kinda worked is weed-block fabric. I've laid down logs and woodchips and put weed-block fabric over it, held in place with heavy bricks, and they 95% stayed put.

I could do that on a larger area: broadfork, pile with 4-6 inches of mulch and manure, sow with daikon radishes and grass, cover with weedblock fabric to hold everything in place, put bricks on top of it, wait for the flood season to end, uncover, let grass and radishes grow up and hold everything in place.

Would something like sunflower stalks be enough to hold mulch in place? Would you have to grow small bushes to do that?

I don't think sunflower stalks would work - too much space between each sunflower stalk.

Probably what I'd need to do is put the mulch down, and sow it with grass, and let the grass hold it all in place.

Hey, I found a two-second video I shot on my phone from 2018 demonstrating the problem:
(that particular box the tree is planted in is a 2x10, so the water at this spot is probably 8" high)


This is showing one tree, but I have about a dozen like that.
The trees survive fine - the bulk of the water drains quickly (within 48 hours), though an inch or so stays around for five or so days, and it stays muddy for about 10-12 days.
The trees don't even show signs of stress, as far as I can tell as an newbie. I've kinda learned the hard way which species don't like flooding (apples, peaches, pears = can deal with it fine. Cherries, Apricots = extremely vulnerable to flooding).

NOTE: I can't plant potatoes or mushrooms or anything else in a flood area, or the flood will likely put botulism on the veggies.
Planting anything like bushes or whatever where the fruit/veggie is always above the water is fine though.

NOTE 2: Don't worry, my entire garden isn't like this. My garden is up the hills and not affected by the flooding. This is just my tree area.

I’d recommend planting some perennials and shrubs that are flood tolerant in the area. Over time they’ll do most of the work of breaking up the soil. If you keep adding manure and mulch around them they’ll work that into the soil too. With the help of beneficial fungi, earthworms, etc of course. That’s how I’ve improved my compacted clay soil. It’s all clay too. After a couple years of this, the soil has much more organic material and is far easier to dig. If it’s easier to dig then it’s also easier for the roots to expand in. I’m starting a new area that  I have to replicate the process on. This time I’m adding some annuals too. Sunflowers, daikon radish, cow peas and squash. The squash will act as a natural mulch if it grows thickly enough. Granted... I’m trying to avoid mowing and I don’t have to deal with flooding. Rain garden plant lists are great for finding plants that can take inundation, but don’t always need to be wet.