Is this a good plan for my super-clay soil...?

On my future land (which I have free but sporadic access to until I buy it), there's a fenced in area against the house where I plan on putting my kitchen garden. It's about 22' x 26'. Twenty years ago the house was built, and in that area my dad put down thick plastic with mulch over it, intending a dog area. It was barely used as such, and weeds (mostly goldenrod) took hold, both above and below the plastic, and for most of this time it decayed & regrew every year, creating 2-3 inches of a lovely texture soil on top of the plastic. This past summer we pulled up all the plastic and hand pulled as much goldenrod as humanly possible (I know I'll be fighting it for a long time). Right under the plastic was solid CLAY. Like, mold-your-grandma-an-ashtray clay.

LAST year, in a small area (3' x 12'?) I hand dug a bit and I layered organic matter, planting some seeds to experiment. Of 9 types of veggies, I got a small pumpkin, lol. Root veggies were thin inedible roots that I couldn't even dig out of the clay, though their leaves would have been edible. I found a mullein plant (which has a long story and was a blessing & a good omen) and I scattered some of its seeds, after reading that the roots go down deep. There are now about 20 mullein plants in a 3'x 12' area.

THIS SPRING, I want to: Plant lots of daikon all over! I plan to let it grow all summer, and at my last fall visit, I'll chop & drop it, add horse manure (free from a neighbor) and then hay as a mulch (also free, from my own land).
Does that sound good?
Is there something I should plant along with the daikon, like a nitrogen fixer?
Is the manure a good idea after chop & drop, so the microbes from it will go down into the daikon and multiply & go to work for me?
Is hay on top a good or bad idea for the winter? I'm afraid its seeds will grow but I read here that a lot of people say that's not an issue. In my small suburban garden the grass took over my food, so I'm wary of that happening again. But it's free and I cannot afford anything else, though I was thinking of asking a neighbor with a wood chipper to help me; there's lots of random brush I want to get rid of.

Thanks to browsing this site, I've done some homework, now please correct me or make suggestions, Oh Wise Ones!

In a section of my yard that has clay soil I planted tree collards, tall kale varieties, and sylvetta arugula. It seems to be doing pretty well, and they are all basically perennial or self sowing in my zone (zone 10). Brassica type plants in general can flourish in clay soil. You could start with those, then down the road add runner beans to further improve the soil and grow up the tree collards and kale stalks.

I think you are looking in the right direction. I would hot compost the horse manure first for weed reduction, and to make the N more stable, with arborist woodchips, straw, and/or your hay and various weeds. Look up Dr. Elaine Ingham's composting recipes for more info. I would loosen the clay with a broadfork or digging fork, add a layer of sticks and then add the finished (not hot anymore) compost. Daikon is a good choice, but diversity is always better for soil life. Nitrogen fixators will be suppressed by the N in the horse manure, so they could be redundant together if resources are scarce. I like wild bird seed as a filler for a cheap bulk soil building mix, as birds will bring their own microbes and nutrients to the party. Locally native wildflowers are also a good addition if seed is available, but would probably not benefit from horse manure much. Horse manure is good for green growth, and can be much less helpful for flowers and fruit.

In your situation, I'd probably try to get as much manure and compost as possible and build a big huge hot pile on there this winter/spring. You need organic matter- the more, the better. Look into free resources like stable manure, chicken manure, sawdust, free bark, seaweed, coffee grounds, mushroom compost, leaves, compost give-aways, etc . Search craigslist and facebook. Then I'd make raised beds in the summer and plant a bunch of easy veggies and legumes- stuff like peas, beans (several kinds), lettuce, tomato transplants, peppers, squash. I'd get a bag or two of composted chicken manure to get stuff going. Daikon might be good, but only if it can penetrate the soil. Daikon doesn't do much in pure hard clay, although the pods are sometimes good to eat. It grows wild in my clay garden and just reseeds itself without making big long roots. But I prefer the small radishes like easter egg for fast edible root crops and legumes like crimson clover and fava beans for soil build-up and nitrogen. Daikon is also good in orchards- the flowers attract bees.

I always try to avoid hay. It almost always has lots of grass and weed seeds. Grass is the enemy. Straw is OK. Try to get  the neighbor's chipper and chip everything you can. See if you can get clean, free chips delivered. Fresh, green, leafy hardwood chips make excellent mulch. The big woody stuff could go into a hugelkultur bed or used as bedliners. There's all kinds of stuff on this website about hugelkultur and chips. Experiment with hugelkultur. Just my 2 cents...

Good luck!

Kim,

I have hard clay myself, so I understand the predicament. Not sure how hard your clay is, but daikon is not some miracle plant, if the clay is tough enough, it will not drill itself into the soil, but will stay in your top soil and just have a fat turnip type form.

I would create pockets of fertility in the area: drill or dig a hole (again, if possible, my clay is pretty easy to work with in the fall/winter as it is wet, maybe yours is different), make it a foot or more deep, fill it with your manure, cover it with your topsoil in a mound form. Next spring, you can plant your melons/squashes in these mounds. Melons/squashes need a lot of space for their vines, but their root system is very local, you don't need to improve the whole area, just the places were roots are.

Now, if you have a lot of time to dig/drill and enough manure/compost/..., you can make those holes close enough so that the worms can travel from one hole to the other holes, so you will also improve the soil in-between the holes (a technique sometimes used to fertilize trees).

M

I can offer you one year of experience with clay soil plus what I've learned from online research, not claiming to be any sort of expert. But it sounds like you're tearing up the whole area anyway, so in this scenario you would probably benefit from tilling as deep as you can with the tools you've got, and mixing in whatever organic matter you can get your hands on. No-till is trendy and has many well-researched advantages, but that doesn't mean that "absolutely never till not even once" is the answer to everything. The downsides of tillage are generally far less applicable when it comes to compacted clay -- you won't really kill the soil microbiome or destroy soil aggregates if there's barely any microbes or aggregates to begin with. Once you have a healthy soil food web going, that's when the daikons become a more useful tool than a rototiller.

Any idea on how deep the clay layer is, and does it extend beyond the area covered by the plastic?   It might have been added as a base for the dog area, in which case it could be possible to remove it completely.

If you're not averse to adding minerals to the mix this article might help:-
https://www.gardeningaustraliamag.com.au/fix-clay-soil/


Good luck, and watch your back - if all else fails it might make good pottery.    A nice raku firing can make good use of the branches etc.  

Hi Kim -

It sounds like you are not planning to use this plot of land for a vegetable garden in the near future, but you want to improve the soil so that you can have a nice garden there someday.

I'm with M.K. I'd put as much organic material on it as I could. Arborist chips are free and break down quickly. Put them on top of cardboard if you want, and then add leaves, branches, kitchen scraps, etc. and put the the horse manure on top to get everything to break down more quickly. Add at least 6 to 9 inches of material a year. It will break down into a nice, loamy soil and it will help to kill the weeds underneath the organic material too.

If you are not planting vegetables in it any time soon, you shouldn't have to worry about the horse manure burning plants or about any of the material stealing nitrogen. Sure, that is happening (that is part of how this suppresses weeds), but the nitrogen will be returned once the composting process is complete. Plus, that phenomenon is only occcuring on the very top of the soil.

I don't advocate tilling. Besides it disturbing the soil biome, potententially compacting the soil, and bringing weed seeds to the top to germinate, it is really darn hard to do with clay soil! I've tried and have the trenching shovel and pick axe to prove it. I no longer try to do that for the most part. Instead, I either add a lot of organic material and let it decompose like I mentioned earlier or I build a mound of soil on top of where I want to plant, put the plant in, put on a couple inches of compost, and then mulch around. All my vegetable beds are raised. These methods have worked very well for us and our soil is much better than it was when we moved in.

I'd skip the daikons for now. What the soil needs is lots of organic material to start with. Just about any plant you put in the ground later will appreciate that.

I've been dealing with clay all my life. First Daikon radishes are are great idea BUT they are a cool weather crop not a mid summer crop. Here in Virginia they often will grow all winter. The longer you let them grow the more good they do. The best time to plant is in late summer after the heat is starting to die down. But in truth they can be planted at  just about all times that aren't 90f+ or below freezing. You should also consider Buckwheat and a few other things.  Buckwheat breaks up the soil fast up on top. It is a warm season crop and will not handle even light frost most of the time.

Go on Yourube and check out Gabe Brown he has some great videos on soil and soil regeneration.

Also read the book Ten acres enough by Edmond Morris circa 1860's.

If you can let things grow until they die and leave them lay while planting other stuff amongst their refuse, this feeds the soil faster and better.

The more diverse you can make your ground changing plants the better. This is a place to use the double barrel shotgun approach! Lay on any and every kind of seed that might help improve soil health while breaking up that clay!

Good Luck!

The more organic material you can mix in the top foot of soil the better!!!

I am letting dandelions grow on one plot, hoping their deep roots will help.
Now wondering what to do to control the dandelions!

Ben Zumeta wrote:I think you are looking in the right direction. I would hot compost the horse manure first for weed reduction, and to make the N more stable, with arborist woodchips, straw, and/or your hay and various weeds. Look up Dr. Elaine Ingham's composting recipes for more info. I would loosen the clay with a broadfork or digging fork, add a layer of sticks and then add the finished (not hot anymore) compost. Daikon is a good choice, but diversity is always better for soil life. Nitrogen fixators will be suppressed by the N in the horse manure, so they could be redundant together if resources are scarce. I like wild bird seed as a filler for a cheap bulk soil building mix, as birds will bring their own microbes and nutrients to the party. Locally native wildflowers are also a good addition if seed is available, but would probably not benefit from horse manure much. Horse manure is good for green growth, and can be much less helpful for flowers and fruit.

Thank you, that's a lot of tips you crammed in there! I really appreciate it! The last part, about horse manure: my grandfather always put it in our vegetable garden, so are you saying in the future (not this year yet) if I want to grow veggies I should *not* use horse manure? I guess you're saying (at the beginning) to compost the horse manure with other stuff beforehand, for best results. Or have a bed for greens and use it there; not with peppers, tomatoes, etc. I will check out Dr. Elaine Ingam. Thanks

Jill Dyer wrote:Any idea on how deep the clay layer is, and does it extend beyond the area covered by the plastic?   It might have been added as a base for the dog area, in which case it could be possible to remove it completely.

If you're not averse to adding minerals to the mix this article might help:-
https://www.gardeningaustraliamag.com.au/fix-clay-soil/


Good luck, and watch your back - if all else fails it might make good pottery.    A nice raku firing can make good use of the branches etc.  

Funny you mention that!! I was looking up how I might be able to use the clay, lol, or let people come take some! I wish I could trade it for compost, wood chips, and manure, lol!

I do know that the clay was not put there on purpose. The whole area (acres, neighbors, etc) is very clayey, and this garden area used to be a mowed-grass backyard between a house and a barn. The aerial photos from when the barn was torn down and the house was built shows a large brown area around the house, of destroyed grass from equipment leveling the land and building the house. Then my dad put down plastic (in other areas, too, he was black-plastic-happy!) with wood chips on top, and then the weed/decay process began on top of the plastic since 2004.

Jen Swanson wrote:Hi Kim -

It sounds like you are not planning to use this plot of land for a vegetable garden in the near future, but you want to improve the soil so that you can have a nice garden there someday.

I'm with M.K. I'd put as much organic material on it as I could. Arborist chips are free and break down quickly. Put them on top of cardboard if you want, and then add leaves, branches, kitchen scraps, etc. and put the the horse manure on top to get everything to break down more quickly. Add at least 6 to 9 inches of material a year. It will break down into a nice, loamy soil and it will help to kill the weeds underneath the organic material too.

If you are not planting vegetables in it any time soon, you shouldn't have to worry about the horse manure burning plants or about any of the material stealing nitrogen. Sure, that is happening (that is part of how this suppresses weeds), but the nitrogen will be returned once the composting process is complete. Plus, that phenomenon is only occcuring on the very top of the soil.

I don't advocate tilling. Besides it disturbing the soil biome, potententially compacting the soil, and bringing weed seeds to the top to germinate, it is really darn hard to do with clay soil! I've tried and have the trenching shovel and pick axe to prove it. I no longer try to do that for the most part. Instead, I either add a lot of organic material and let it decompose like I mentioned earlier or I build a mound of soil on top of where I want to plant, put the plant in, put on a couple inches of compost, and then mulch around. All my vegetable beds are raised. These methods have worked very well for us and our soil is much better than it was when we moved in.

I'd skip the daikons for now. What the soil needs is lots of organic material to start with. Just about any plant you put in the ground later will appreciate that.

Correct, I don't plan to plant much, if anything, this year or next. Anything I plant would merely be an experiment, and I can't be there regularly to water, weed, etc. But I'm seeing this as a great opportunity, because I'm not *relying* on this to feed me; I have time to plan & prepare. My experimental planting last year was just to see if anything could break down into the clay. Turnip did, but they remained as thin as my pinky finger. So, I will probably plant some daikons to see what happens, because I can't *not* experiment, lol, and it will be satisfying to see something to bust down there, but I will no longer think that covering the area with them will solve my problem.

I don't want to till, and honestly I don't think our little electric tiller will get through this clay! I was thinking of getting my hands on a broadfork (odd birthday request, lol, huh?) and just doing it a little here & there and jamming organic material down in there however I can. Like, shove twigs & dead matter in whatever crevices I can make. This is how I spend my vacations, btw :-D the land is my dad's old hunting cabin, and when my husband & I go there we daydream, repair, plan, kayak, dream, repeat, lol

M.K. Dorje Sr. wrote:In your situation, I'd probably try to get as much manure and compost as possible and build a big huge hot pile on there this winter/spring. You need organic matter- the more, the better. Look into free resources like stable manure, chicken manure, sawdust, free bark, seaweed, coffee grounds, mushroom compost, leaves, compost give-aways, etc . Search craigslist and facebook. Then I'd make raised beds in the summer and plant a bunch of easy veggies and legumes- stuff like peas, beans (several kinds), lettuce, tomato transplants, peppers, squash. I'd get a bag or two of composted chicken manure to get stuff going. Daikon might be good, but only if it can penetrate the soil. Daikon doesn't do much in pure hard clay, although the pods are sometimes good to eat. It grows wild in my clay garden and just reseeds itself without making big long roots. But I prefer the small radishes like easter egg for fast edible root crops and legumes like crimson clover and fava beans for soil build-up and nitrogen. Daikon is also good in orchards- the flowers attract bees.

I always try to avoid hay. It almost always has lots of grass and weed seeds. Grass is the enemy. Straw is OK. Try to get  the neighbor's chipper and chip everything you can. See if you can get clean, free chips delivered. Fresh, green, leafy hardwood chips make excellent mulch. The big woody stuff could go into a hugelkultur bed or used as bedliners. There's all kinds of stuff on this website about hugelkultur and chips. Experiment with hugelkultur. Just my 2 cents...

Good luck!

Sorry everyone, that I'm quoting nearly everyone, lol, but I'm thankful for all your comments...

M.K. - I like your sentence that says to borrow that chipper and chip everything I can. There are large areas of brush & weeds that I'd like to clear, so if I can chop that all down, I could just send it all through the chipper and make my kitchen garden area into one big 'compost pile', I guess. I'm not there full time so I won't have kitchen scraps, but if I do this again in early summer with lots of leafy matter or grass clippings (which I'll be abundant in a few times), then I should be getting somewhere. I can look elsewhere, but even from my own property and my neighbors I can already get:
- chipped bushes
- horse manure
- grass clippings
Thanks for the brainstorming!

I don't have large enough trees for hugelkultur; nothing bigger than a sapling.

Compost will not fix this.  It will help, but that will not last.  You need to change the physics of the soil.  

Heavy clay is an oxygen problem.  You need to mix coarse sand into that soil.  Given the size of that plot, I'd rent a trencher for the afternoon and trench deeply across that garden as tightly as you can while still keeping the trenches open.  Backfill the trenches with a blend of wood chips, compost, gypsum, and sand.  Do that across the whole garden one way, like all east to west lines.  Backfill them all, and level it off, and then do it again the other direction north to south.  The trencher will rip up and through what you just put down, but also rip into all the spots you missed between the rows.  

If you can pick the trencher, get one that goes narrow and deep.  If you're gonna have this garden for many years, I'd do this and get it fixed right, and right away.  Skip the rehab years and just get it done.  

I'm sorry to disagree with Christopher, but sand and clay make cement.  Look it up.That apporach is not advisable. Lots of organic material will make your soil amenable to being a vegetable garden over time, and it's way easier than renting a trencher and buying a whole bunch of material to fill in your trenches with. I've done it myself and so have many of the other people on this forum.

You might get woodchips free ... check out chipdrop.com

USGS has a soil survey for various elements, including essential and toxic ones to plants.
https://pubs.usgs.gov/sir/2017/5118/sir20175118_geo.php
The color is national percentile based as well as absolute values for top 5 cm. At least I found it correlates with my soil test results fairly well. (Utisol of Ozarks is very low in fertility.)

Look up the interactive maps for a general idea of soils in your area. If something essential is significantly low, now is a good time to amend it before you grow perennials. Or if the contamination of heavy metals is high, you may want to avoid eating root crops.

larry kidd wrote:I've been dealing with clay all my life. First Daikon radishes are are great idea BUT they are a cool weather crop not a mid summer crop. Here in Virginia they often will grow all winter. The longer you let them grow the more good they do. The best time to plant is in late summer after the heat is starting to die down. But in truth they can be planted at  just about all times that aren't 90f+ or below freezing. You should also consider Buckwheat and a few other things.  Buckwheat breaks up the soil fast up on top. It is a warm season crop and will not handle even light frost most of the time.

Go on Yourube and check out Gabe Brown he has some great videos on soil and soil regeneration.

Also read the book Ten acres enough by Edmond Morris circa 1860's.

If you can let things grow until they die and leave them lay while planting other stuff amongst their refuse, this feeds the soil faster and better.

The more diverse you can make your ground changing plants the better. This is a place to use the double barrel shotgun approach! Lay on any and every kind of seed that might help improve soil health while breaking up that clay!

Good Luck!

The more organic material you can mix in the top foot of soil the better!!!

Ten Acres Enough - can't double that recommendation enough. Wonderful book.
We have tons of clay here and using wood mulch and using the pitchfork as a broadfork to aerate the soil and then building on top of the clay. Double digging and working in kitchen scraps and topping with cardboard and leaves has really helped too. That all and raised beds, which may or may not have a box of scrap untreated wood around them. Nothing fancy. All very low key here. And compost compost compost!

Thom Bri wrote:I am letting dandelions grow on one plot, hoping their deep roots will help.
Now wondering what to do to control the dandelions!

Get chickens?
Plant some tall things to shade them out?

Honey bees do adore them, at least in my ecosystem.

if it ever gets really dry there, the clay will crack ... sometimes over a foot at my place.   It wouldn't hurt to have a couple bags of play sand on hand to pour in those cracks ...no dig trick #1.

I'm on lunch @ work off property, so this will be much shorter than I'd like.
Western West Virginia,  up on the ridges of the hills, and a foot or less down I hit a fairly pure yellow clay that goes for at least another foot. So far I am amending spots for fruit trees (dig extra deep and backfill with purchased soil/compost), no amendment for stuff like horseradish or comfrey, and building raised beds and hugelkultur beds for larger crops in the future.
I will be checking the suggested links.

Clay + sand = adobe. Resist any temptation to "lighten" clay soil by adding sand. You want organic matter, and lots of it. If you have cracking, that is your opportunity to pour sieved compost and biochar down those cracks. Put mulch on top. Wood chips are your not-so-secret weapon. Add more mulch. Avoid digging, especially when the soil is especially dry or wet, but avoid it in general. Get roots into it. Add more mulch.

Phil Stevens wrote:Clay + sand = adobe. Resist any temptation to "lighten" clay soil by adding sand. You want organic matter, and lots of it. If you have cracking, that is your opportunity to pour sieved compost and biochar down those cracks. Put mulch on top. Wood chips are your not-so-secret weapon. Add more mulch. Avoid digging, especially when the soil is especially dry or wet, but avoid it in general. Get roots into it. Add more mulch.

To add to my little plan, we are raising rabbits as much for the meat and pelts as for the butt nuggets of pure gold. It's often mixed with waste hay or straw that falls through, and urine. It all goes to a "compost" heap for a couple months until it gets distributed to raised beds, hugel beds and side dressing for fruit trees and just about anything else I'm putting in.

Come spring I'll be purchasing a few cups of fish bait worms to add to the raised beds to help work their magic to the layers of leaves, bunny compost, wood chips, chop n drop comfrey that's scattered everywhere near garden beds and what I hope to make a food forest with the mini orchard area. I plan to use any mown grass in the mix as well.

I'm going to have to come up with a very sandy raised bed for some root crops until the soil builds deep enough in all the other grow beds.

Heavy clay is quite foreign to me,  but now I have an abundance of clay to play with!

Deedee Dezso wrote:I'm going to have to come up with a very sandy raised bed for some root crops until the soil builds deep enough in all the other grow beds.

If you don't have big rocks in your topsoil, a broadfork can do wonders. Spread compost and fine organic matter (like bunny butt nuggets - love that term!) on the surface, then use the broadfork to lift and open up crevices for the good stuff to fall into. This gets the loosening activity happening at depth and as a huge bonus you won't be disturbing the layered soil ecosystems all that much, so you don't get the fertility hit and erosion that comes after tilling.