Coping w/ heavy clay?

Hi folks.  I live on Minnesota's North Shore.  I bought an old homestead here where I have an approximately 5 acre pasture.  My goal is to eventually put a portion of this field under mixed organic vegetables.  That being said, we here in Northern MN aren't necessarily blessed with ideal soil conditions.  Rather, we have mostly rocks & heavy clay.  And this isn't to say that I have a "clay loam."  Rather, beneath my approximately 6-10" of top soil I have an endless layer of pure clay before one hits bedrock.  This is the sort of clay that is near impossible to penetrate with a spade shovel or digging fork.  It's heavy and unforgiving.

Does anyone have any experience with dealing with clay in this regard?  Starting last year, I had pretty good luck with some cover cropping.. namely a mixture of oats, rye, and peas w/ tillage radish sown throughout.  The radish seemed to make some progress in terms of breaking through the top of the clay.  In the fall, I hand-crimped everything and my hope is that the radish will rot in place, leaving channels for air & water.

Additionally, I'll mention that I produce a substantial amount of compost here at my place in that I collect compost from the local food co-op.  It's been advised that I spread that regularly.  Also, I came into a year's worth of cow manure from a farm down the road and have intentions of spreading that over the next couple years.  Above all, I intend to keep cover cropping with the hopes of green manure and/or bio-tillage.

Any additional thoughts or experiences would be greatly appreciated!  Thanks for your time.. I love this site!

One trick I used on my last farm for gardening was instead of trying to remediate an entire garden area I used my gas powered auger and dug 8 inch diameter by 2 to 3 foot holes and put my remediated soil in there.  This allowed me to give good soil down to the water table for "each" plant with only a fraction of the material needed to remediate the entire garden area.

In the end it is all about organic material added to your soil, but on that scale it becomes a crazy amount of organic material.

One way in the long term to have quite an effect is to plant trees, the constant leaf litter helps to build up organic material and the trees roots bring up nutrients from deeper in the soil.

There are a lot of plants that grow crazy well in poor soil and create large amounts of organic material, keep growing things like that as cover crops and then concentrate the excess biomass in the areas that you want to remediate.  The amount of organic material needed to remediate just the top four to six inches of soil of just one acre is insane, you start getting into dump truck loads of material a year for years to accomplish it.  The scale of that can be a bit intimidating.

Some tricks that can be useful and reduce the amount of material in the short term is raised planter boxes, trenches, holes etc so that you can get to growing in the near term without remediating "all" of the soil.  

Building topsoil takes time, just like growing trees...

Will just add to Roy Long's sentiments.  A good link here:  https://renegadegardener.com/care/soil-the-way-with-clay/

And try to track down Bryant Redhawk's soil series within this Permies.com site.  Good luck!

Making Hügelbeten could be ideal here, but for 5 acre, or even just a part of it, the manual approach often seen on this site is probably not practical. You could do the same kind of thing using mechanical means, like, for example, as seen in this video: https://www.facebook.com/sparkberrybergum/videos/1674050966020364/.
I think you need to be a registered Facebook user to see Facebook videos, and they translated their content to Dutch, not English, so that's not ideal, but from the imagery most of what they're doing is pretty clear. It's not on heavy clay they're working, it was just a low lying field which remained too wet most of the time, so that was their main reason to go with Hügel culture. They're a blueberry farm, they're bringing acidic soil on top of the wood to accommodate the blueberries. The hills would be made differently for different crops, of course.

If something in the video is unclear, I may be able to clarify, as I can understand what they're saying, and this is actually in cycling distance to where I live.

Adam, one other quick item of concern.  Are you literally on the "North Shore"....as in, within a mile of Lake Superior?  If so, you may also want to consider some sort of greenhouse or hoop house to help with heat units when growing in the summer months.  And please consult with some of the longer-standing horticultural/gardening centers about what will grow at your location.  My sense is that close proximity to Lake Superior will cool your temps to a point where certain garden crops that grow pretty well just 2-3 miles from the lake will have a hard time growing if you live closer to shore.  Just something to possibly look into.

Wood chips and lot of them!  Build up instead of trying to "fix" the clay.  The worms will do the tilling at their own pace.

Gray Henon wrote:Wood chips and lot of them!  Build up instead of trying to "fix" the clay.  The worms will do the tilling at their own pace.

I've no idea about your physical location exactly, but sometimes you can get lucky and find a tree trimming company nearby or something that could make use of your property as a place to dump tree trimming materials.  A single company can produce almost unimaginable amounts of waste each year.  That material chipped up or allowed to sit and mulch over a few years could add quite a bit to your soil on a scale that might be useful to you.  My buddy owns a tree trimming service and bought 40 acres just 3 miles down the road from me and I pay him $10 a dump truck load for wood chips that he has to pay to get rid of at the landfill.  It pays the fuel and time for him to bring it to my house and saves him a bit at the landfill.  Works well for both of us.

He is still dumping probably 10 loads a month at his place, he has areas that must be a good 6 feet deep in wood chips at this point and he has only been there for going on three years now.  Before he took over the company and bought a chipper I was best friends with the previous owner and I would take 20 dump truck loads or so a year of branches at my last farm.  My goats would then strip all the bark from the branches as food and then I would pile the refuse in piles and allow them to rot down into soil additive.

John Weiland wrote:A good link here:  https://renegadegardener.com/care/soil-the-way-with-clay/

Killer article!  That was a fun read and I happen to be less than a five hour drive from the Twin Cities.  Although the article was written in 2017 I'll follow up and see if the guy who was selling rice hulls in the Cities is still around.  I'd consider experimenting with a few bales!

Roy Long wrote:That material chipped up or allowed to sit and mulch over a few years could add quite a bit to your soil on a scale that might be useful to you.

I bought a small Craftsman chipper/shredder last year and have been slowly chewing up and incorporating some of the woody brush that lives on the edge(s) of my pasture.. namely dogwood and alder.  I add it into my compost and it seems to do well..

J Grouwstra wrote:Making Hügelbeten could be ideal here, but for 5 acre, or even just a part of it, the manual approach often seen on this site is probably not practical.

My apologies.  My original post was misleading.  I have a roughly 5 acre field but I'm not intending to put it all under vegetables.. that'd be a dream!  Instead, I've started by turning over a 70' by 70' plot with a one-bottom plow, tilling in composted horse manure, and then cover cropping that last year.  This season, I'd like to more or less replicate that, maybe twice over (so 2 additional patches at roughly 70' by 70' per).  Regardless of the details, the important thing is I'm not trying to turn 5 acres of clay w/ limited topsoil into 5 acres of tillable loam.  That being said, wanna point me to some of the "manual approaches" you referenced?  I have a 35hp tractor with a couple attachments as well as an arsenal of hand tools..

Adam Dettman wrote: I'll follow up and see if the guy who was selling rice hulls in the Cities is still around.  I'd consider experimenting with a few bales!

They're used in brewing to prevent a stuck mash, so you may be able to track some down through a brew supply place or someone who sells malt.  Maybe even ask any craft brewers if they could get some bales for you.

There's a section on Hügels on this site here: https://permies.com/f/117/hugelkultur and I do not have a specific thread in mind right now. You can also browse YouTube. Often it is presented as a method that saves having to irrigate, I feel that's a bit misleading, the method has originally been applied to very wet regions, and gives benefits in any sub-optimal situation.  
The principle is hills with decaying wood underneath, and any organic matter can be added.
I'm on heavy clay myself. If I lift a spade of the original clay in the rainy season, I'm greeted with a rotten smell, as little oxygen can penetrate this compact soil I have. It's the natural habitat of several root weeds, where any crop I want to grow has a problem competing with, if they can get established at all. So I'm hügeling 100% of the vegetable field. It immediately defeats a lot of weeds and brings air into the soil. It's taking years before the soil itself is actually transforming, but it's removing a lot of frustration for me straight away having tackled an area. It's labour intensive to start with though.  

Adam Dettman wrote:... Instead, I've started by turning over a 70' by 70' plot with a one-bottom plow, tilling in composted horse manure, and then cover cropping that last year.  This season, I'd like to more or less replicate that, maybe twice over

I don't know but from what I have gathered from this site so far is that you are doing an excellent job with the cover crops But you'd create more top soil by not tilling it under.

That being said, my garlic bunches (used daily for cooking in the winter) seem to flourish in the clayey soil where the compost has been turned under.

Adam Dettman wrote:  Starting last year, I had pretty good luck with some cover cropping.. namely a mixture of oats, rye, and peas w/ tillage radish sown throughout.  The radish seemed to make some progress in terms of breaking through the top of the clay.  In the fall, I hand-crimped everything and my hope is that the radish will rot in place, leaving channels for air & water.

Additionally, I'll mention that I produce a substantial amount of compost here at my place in that I collect compost from the local food co-op.  It's been advised that I spread that regularly.  Also, I came into a year's worth of cow manure from a farm down the road and have intentions of spreading that over the next couple years.  Above all, I intend to keep cover cropping with the hopes of green manure and/or bio-tillage.

Any additional thoughts or experiences would be greatly appreciated

Unfortunately,  when I live in N Minnesota, I was at the latitude of Duluth, but in the central part of the state. We had sandy soil .....and lots of rocks.  I will second the motion to use high tunnels.  They will add a month or two to your growing season.  They will also provide a framework for you to systematically improve the soil.  There have already been a lot of good posts on that.  

start a pottery

I know a guy near duluth who grinds his own granite to make glazes for his locally sourced clay

I have 3.5 acres kike that. Previous stewards of the field trued ti ditch ti drain the shallow ponds that are in a natural big Z across the field so that they could plow in the spring. This was a mistake because it quickly dries rock hard during our 4 month dry season.I have worked to restore the water retention.  Alfalfa and vetch are established  in some areas and I mow them with a scythe when the seed is ripe and move ti to bare areas of the field where it seeds. moles the ponds tunnel towards as the field dries Then the water fallow the tunnels out into the dry areas when the rains return.
For areas in zone 2 where I want to garden I take what I mow from the field and pile it a foot deep then cover it with a fabric to keep the sun and wind from drying it out. Keeping the clay from drying seems to be the key to its productivity. A system that avoids working the soil when it is wet but allows planting in the spring in protected soil works best.

Add me to the list of folks that vote build.your soil up. But at a larger field.scale I have heard of folks using chisel plows in a keyline pattern to improve infiltration. That might be something to look into.

For garden scale though, woodchips, hugels, rotten hay/straw, whatever massive organic pile up you can manage on your beds

Since you say you aren't trying to make the entire 5 acres tillable, I'll tell you what I've done in my garden, with permanent mounded beds. Caveat: I live in WV, zone 6, so I'm not dealing with the short growing season and brutal winter that are an additional obstacle for you, and my clay is mostly not the most pure and awful stuff. When I got here 11 years ago I chose an area near the upper and best end for the garden, but the uppermost I reserved for the orchard as it has the best drainage and the fruit trees need deeper drainage than the vegetable garden. Someone mentioned "poor soil" but clay is usually rich soil--you should certainly have yours tested. Having permanent beds means I don't ever walk on them and can heap all the topsoil in the beds leaving the aisles hard and poor, and my annual improvements stay in place...mostly. Of course, the produce I remove and the weeds I put in the compost pile are removed organic matter so that has to be returned every year, in the form of compost or manure or leafmold. I keep good records and have found I get best results from leafmold. If I remember from my one winter in Little Marais and Finland, you don't have a lot of hardwoods for leaves...my other secret, and this is controversial, is adding sand. I argue with my neighbor about this as he believes the common mythology that clay plus sand equals concrete. The proof is in the pudding, my soil is much improved by adding quite a bit of sand...I've read it should be coarse sand, and I think you need to be sure to always add organic matter as well as sand. This is a trick for improving small areas. I argue with the same neighbor about tilling--he is against it, but he has sandy soil (only 700 feet from garden), and non-till works for him. I turn my beds with a shovel and work in amendments once or twice a year.

Adam Dettman wrote:Hi folks.  I live on Minnesota's North Shore.  I bought an old homestead here where I have an approximately 5 acre pasture.  My goal is to eventually put a portion of this field under mixed organic vegetables.  That being said, we here in Northern MN aren't necessarily blessed with ideal soil conditions.  Rather, we have mostly rocks & heavy clay.  And this isn't to say that I have a "clay loam."  Rather, beneath my approximately 6-10" of top soil I have an endless layer of pure clay before one hits bedrock.  This is the sort of clay that is near impossible to penetrate with a spade shovel or digging fork.  It's heavy and unforgiving.

Any additional thoughts or experiences would be greatly appreciated!  Thanks for your time.. I love this site!

I used to live in a heavy clay site, near Vesper, WI. and it was low land, to boot and very acid, like 5. We didn't *even* have rocks, that would break up the soil. I can tell you how to NOT remedy. We thought that indeed, it was too heavy, so we added sand. [Yeah: I hear you all laugh already. Stop it: We were young and stupid, OK]. The first spring after our "intervention", we had to let the soil 'dry' before we could till [low land, remember].
Long story short, by the time the land was ready to be tilled [yes, we were tilling too in these days] the soil was the consistency of dried cement. We absolutely could not plant. Had we made elevated beds in which we added good soil, we might have done OK. Since it was low and very acid, we put in blueberries. That kinda worked.
So I'm not in a good position to give you good tricks for dealing with rocky clay, but at least I will have made you laugh.
Incidentally, I think you are on the right track with daikon/ field radishes: They will break the soil and help... some. 5 acres is quite a lot of ground but perhaps you could work the area in elevated rows? gathering the rocks in the alleys?

Like I said, adding sand has worked very well for me. However, my beds are somewhat raised--no sides but they're kinda mounded, like 3 to 6  inches above the aisles, and I added organic matter as well. I want to use daikon radishes, not so much in my main vegetable garden which is in good shape but in my remaining flat space, 25 by 65 feet. That soil got very hard and unproductive because I was counting on cover crops to add organic matter and had trouble getting them in early enough to be productive--one year they didn't take at all. Here, I can plant rye and hairy vetch until late October or into November, but daikons need to be in by the end of August. Trouble is, I'm using that flat ground for field corn or sorghum and potatoes or tomatoes...the corn and sorghum being about the only things that don't like raised beds and the other two just needing a place to rotate into. All are typically ready for harvest in October here so it's hard to get daikon in or field peas  and sometimes the rye and vetch don't take well. I am still learning about cover crops; I know it's possible to sow them before the previous crop comes out but I have not managed this yet. I have taken to using them in my garden now but mostly only winter peas and vetch, which are easy to remove in the spring--rye and wheat come out of the way easily in my neighbor's sandy garden but in mine, digging up a rye clump gives me a solid, hefty thing that won't degrade and chop up easily. What does work--thank you, Cindy Conner--is planting the rye or wheat in rwide ows and cutting it when it's shedding pollen or even at maturity if I want to harvest the grain. Cut then, 95% of the plants die and the roots quietly rot into the soil while your new crop grows in the open lanes--you can use the cut stalks as mulch too. You do have to wait two or three weeks in some cases because rye and maybe wheat exude something to inhibit germination, but it doesn't bother transplants or usually, big seeds.

Was it in something Paul Wheaton posted where I read to dig about ten deep holes spaced around the area and dump a bunch of organic matter into it and leave it? That the worms and soil life would use it to break up the rest of the soil?

What I'm wanting to do is dig five-gallon buckets drilled full of holes down into places along my path, then put a round stepping stone over the top as a cover. It'll look like a path, but there will be organic materials inside for the worms to go in and out and dine on. I'm thinking about actually pouring my own stepping stones using a bucket lid sprayed with cooking spray to keep it from sticking, and then I can get a secure fit that will be more stable than just trying to put a 12" stone on top...which will just barely cover the bucket rim. Or maybe go for the 14" ones if I can find them.

If your clay is acting as a kind of hard pan, since you have a tractor why not buy, rent or borrow a single foot subsoiler?  Put your organic matter on then subsoil the garden plot. Some of it will fall down into the clay and help to keep it broken up.  If your clay is anything like what I used to deal with in GA you will have to keep up applying the organic matter.  Red GA clay just consumes organic mater like there is no tomorrow.  

I think giving compacted clay room to horizontally melt/expand can rapidly increase the rate at which it can be made more loamy and useful to plants.  

As a shear or steep clay wall slumps out horizontally over the course of a few years, it creates a lot of porosity in the way of cracks filled with air (rather than only displacing lost height. I think)

A person could take flat pasture land and make it corrugated, with like shear 4 foot box trenches, piling the dug up/tilled earth on the level ground between each trench.   Massive project, but I think in a few years you will have quickly created massive amount root space in otherwise compacted ground that a person can't really get from a till or planting alone (2 or more meters in depth).   A person would also need to plant perennial deep rooters and be sure not to compress the clay while wet or till it again...

Also the amount of rainfall could be linearly related to how much useful melting/crack action is had in steep clay embankments.  Also rock content.  If it's mostly rock, it might not melt much at all.

Best of luck with your clay!

I live in Detroit, MI. I bought a fixer- upper house adjacent to a vacant lot.  The other 2 houses next to the vacant lot were bulldozed into their basements and I bought those lots two.  At the time, it was legal to bulldoze a house into its basement and cover everything with fill dirt.  This was 2001.  I didn't know anything about restoring land let alone nasty fill dirt where dandelions wouldn't grow. I was also spending most of my available money on fixing up the house 'cause I moved in with no windows, no doors, no furnace, no plumbing, etc... long story.

Anyway, I read that white clover seed might enrich the soil over time.  So I bought 5 lbs and spread it out by hand over three 40' X 125' city lots.  Somehow that clover took root in patches, died, and new clover took root in the new organic matter.

By the next year, the clover patches were widening and  filing in.  I grew a few vegetables in containers cause when I tried to dig into the soil, after 4 inches, I hit clay, bricks and other debris.  The soil tested fine, but it was full of bulldozed junk.

By the 2nd year, I decided to build keyhole beds.  That worked really well and my love of organic gardening began.  I currently only have raised beds for any type of gardening here: vegetables, fruit bearing shrubs, 4 fruit trees, and hardy kiwi vines.  The lawn/field is lush with all kinds of grasses, clovers, and even some mullein.  I always dread April/May because I have to pay a contractor to mow it every 2 weeks!  But by focusing on mowing over clover and leaving it in place as a mulch, the land has come back.  I've notice 4 types of bumblebees, dragonflies after the Summer rains, and lots of moths and butterflies.

Wood chips are good for paths and will still build the soil underneath them.  I also get spent mushroom "cubes" a local grower, and hops waste from a local brewer to help build my soil in the raised beds.  Since you have 5 acres, you might be able to get truckloads of veggie waste to spread where you need it mixed with a few yards of topsoil.   Alfalfa has 5' deep roots.  That and peas are a good grow-then-cut cover crop. One year I mixed 50gallons of horse manure with wood chips and grass clippings for an interesting 1 cubic yard compost pile.  It worked in under 4 months but stank!  Hope this helps.

Compost/manure; no-dig raised beds and time are the only suggestions I can offer. What I have here in sunny Devon to grow on is very heavy clay with flint. Very difficult to work, that is why most farms in our very rural area grow grass for all the cattle and sheep that we grow. So get nature to do the work for you and minimise the back-breaking idea of doing any digging. I wish you the best of all growing seasons. I hope that COVID-19 has not visited you and yours yet; stay safe.

Adam,

There is a lot of great information here.  Have you considered starting out with some raised beds?  Raised beds can be incredibly productive and you can start them pretty much immediately while you take a longer approach with the other areas you intend to plant.  I am not suggesting that you cover your entire garden area in raised beds, merely start a couple just for starters.

I, too had issues with dense, hard clay and the best thing I did for the clay was to get a bunch of woodchips piled on my garden beds.  Within a year the soil was dramatically better.

Just a thought,

Eric