Clay Dominant Garden Soil Remediation

Sick Plants & Problems
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I’ve heard a few different things about the best way to amend soil that is substantially clay into something usable. Many areas where I am have a whitish clay embedded in river banks, and a reddish clay in the soil around residential areas. I want to be able to advise my growing friends about what to do with their native soil to make it awesome.

I’ve heard clay soil is generally packed with valuable nutrition, but cannot easily be accesses since it compacts. I’ve heard adding sand is a great way to make bricks and block out plant roots from reaching water underneath.

So, it seems that incorporating organic material, especially that which can aerate and lighten soil density is best. I have heard a number of other things to do remediate poor soil, like planting beets or potatoes as a way to break up the structure of blocked up soil. Some recommend cover cropping (and subsequent green manure) with Fabaceae plants especially, for potential nitrogen fixation and mycorrhizal activity.

A lot of recommendations also amount to mulching to improve moisture retention and encourage active topsoil life.

What other general or specific recommendations would you make for someone trying to make do with the soil around them?

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You’re going to have a hard time planting directly in clay if that is the primary component.

As you mention above use a lot of organic material, a lot of gypsum and dig it in thoroughly. I would also add pumice or an aggregate of some kind.

The gypsum will break up the clay into much smaller particles. The gypsum will improve drainage, add calcium, add sulfur, and helps increase the ph.

It is a google-friendly topic. Good Luck!

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Your going to want to till in lots of sand and compost. Put down a thick layer of wodchips (can get usually get for free from landscaping companies and tree trimmers). Over t time, the wood chips and will all compost as well.

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Welcome to the forum @RatsboggleBiological :+1:
Good to have you and a very awesome first thread you made!

Definitely covercrops, combined with a thin layer of woodchips / sawdust
with on top of that a 2 to 5 cm (1 to 2 inch) layer of horse manure and ideally some various mycorrhizal mycelium sprinkled between the woodchips and manure.
Elm oyster mycelium is very tough.
Garden giants are extremely good at retaining water, very thick strands of mycelium.

Alfalfa has stupid deep roots, up to 10 times the height of the plant or something ridiculous like that.

Buckwheat, corn and sunflowers for medium sized deep-ish roots.

Black raddish for big chunky roots, prune half of the leaves when they’re big for mulch and leave them to rot in the ground when they stop growing new leaves.
Brings a big volume of new soil!

And vetch ofcourse!

When they start flowering, chop and drop half of the covercrops and let the other half go to seed so you don’t need to buy any more.

You can already sow your cannabis crop along with all of that and do the same, let half go to seed and return to the soil. Stronger plants every year through natural selection.
And always keep all the covercrops growing along with your cannabis for optimal endless regeneration.

Also create some waves in your soil, bare swales as footpaths in a geometric pattern, for catching water so it doesn’t all drown or wash away during a deluge, and so more water can sink into the soil instead of evaporating.

An acacia tree here and there perhaps, fixes nitrogen and can be pruned twice a year I believe, so it’s all extra mulch and woodchips if you have a chippingmachine, or firewood, or simply wood you can use for anything.

Sowing dandelion (10% calcium) on purpose is good too, makes lots of calcium bioavailable, deep roots too!

Don’t hesitate to ask any further questions here, happy to help!

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First, what are the size/scale? Is the plan to remediate/improve 100 sq ft or an acre+ or using bits of harvested clay to potting mix?

I’ve fought with.clay & it sucks.

Essentially everything posted so far is true & relevant but the long term goals should be considered too. It’s easy to waste a lot of time learning the hard way(the way I usually do :sweat_smile:).

As a general rule for potting mixes clay shouldn’t exceed 10% in my opinion.

The time aspect is the big variable— if you want it to be “fixed” ASAP then it’ll take more work than if you can wait ten years. :man_shrugging:

:evergreen_tree:

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Not exactly on point but you could dig some big holes and fill them with something better.

If it doesn’t drain out the bottom it’d be a problem though.

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Theres a product called Clay Breaker sold in garden centres, dunno if you can get it where you are

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Not sure what scale you are looking to do this on but for a single plant or small area I would dig out the clay, add organic matter like compost to the bottom of the hole, let the worms travel and aerate. Then mix the existing clay with peat (not compost) and add back to the hole. Then grow clover on it…cut what clover is above ground when it flowers, and seed again…use the cut clover as a mulch…it takes some time, but the soil will respond and will work much better in 2 seasons…all gravy after that. Fava beans, alfalfa also work. No potatoes, no sand. If it’s really bad clay.like impervious…then pitch the bottom of the hole and maybe even a small trench going away at the low point. You can do 3 crops of black eyed peas in one season also. Cut when they flower and turn in…you will get both nitrogen and tilth from that and they are in the soup bean aisle for $1.50 lb :slight_smile:

…old grow soil would be a great add to clay too. Adding perlite or rices hulls for aeration is also good.

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When we moved a year ago the garden beds in this new place needed serious remediation. It was nearly all sand. I added tons of peat and Malibu’s compost and covered it all with a thick layer of cardboard and then straw, sprinkled everything with red clover seed and let it sit for the year. It is alive now but will continue to be a work in progress.

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At our old farm I used to use a 50 / 50 mix of our indigenous clay soil and horse manure. I’d dig up the beds and just mix it all in together with a few handfuls of gypsum and kelp and it worked wonders. Top dress with worm. Castings, gypsum, kelp and alfalfa meal and you should be good
Edit : the soil was tested prior to any ammendment…
@cannabissequoia 10% is ideal when building a soil… When I’m making my potting mixes I use peat and wc with an added 10% total volume clay

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Humic acid is supposed to be really good at conditioning soil. So, with most of the other advice, adding humic and lots of microbes, is another important addition. Humic Acid feeds mircobes, too. I’m still figuring a lot of organic stuff out myself. My natural dirt here is clay also. I haven’t had it tested yet.

My neighbor’s place is almost all dirt/clay, but dandelions grow thick on it. He’s 82 and collects the dandelion greens for one of his friends who loves cooking them.

Should be a lot of reading to be had on the subject. You can also send in a soil sample to a place like Build A Soil, and they will give you a plan to proceed. Not saying you need to use them to buy stuff, but to get an opinion from an expert in soil. peace

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Building raised beds if you got access to loads of organic material and compost is how I’d go about it.

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Check out the book “the one straw revolution” the author takes a barren clay landscape and turns it into a farm plot. He used acacia trees, rice straw, and alfalfa covercrops to fix it.

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Doesn’t make sense when you can just get seeds instead and never have to spend a dime after that. Alfalfa has stupid deep roots that activates the fungi that break down rock. It’s so much more beneficial to just sow it. Such a waste of resources to bring it to your garden when you can just sow it. :+1:
On top of that you fix nitrogen through activating another group of bacteria which would otherwise remain dormant, it improves drainage, holds moisture, …

Be more lazy, stop hauling shit around.
You can fix it all with a diversity of covercrops.
There’s a plant for every deficiency you may have.
And all you have to do is SOW them, not buy the organic matter from somewhere else.
Shifting organic matter and soil all over the world doesn’t help in the long term and wastes fossil fuels, creates more packaging which creates more waste, it all costs money, etc.

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Thanks. That sounds like a really good book. I checked it out on Amazon. I think I’m going to get that for some good reading. Seems like we still have some good reading weather left in this year.

I’m trying to move on the KNF. I keep peeking in on your thread when I can and really enjoy it so far. I bought some things to start the LABS (organic milk and a turkey baster) and I’m gonna make some wooden boxes to collect the IMO. The weather is getting perfect right now. Thanks for all of the info in one place! peace

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Much love. If you ever have any questions on organic soil, knf, natural farming in general feel free to hit me up💜

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I don’t think you’ve ever done what you suggest tbh… To plant Lucerne or alfalfa as a cover correctly takes 4 years minimum.
Also why is he trying to fix his nitrogen when he’s trying to break down clay to grow in.
Cover crops are not the answer to all organic problems man.
You seem to pick at what I say like my info is wrong. You in my thread trying to school me on methods I’ve been using for decades like I need help…
To tell someone who wants to break up clay soil to plant alfalfa is just garbage

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It is really difficult to change soil texture. All our soil has clays of different varieties, and not much else :frowning: Lot of mineral value in clay, so most around here have just learned to work with it. Organic material, and mulch like pine fines (if you can keep it from floating away when it rains) help a lot. But it takes time.

If you’re just talking about holes for pot plants, dig big… wider is better than deeper, rough up the edges so roots can penetrate and hold, and add compost, and job’s a good one. The clay will help hold water if it’s dry.

We try to avoid peat products for a few reasons, but firstly because if it gets dry, it’s hyrophobic… it’s a bitch to rehydrate.

Gypsum is a really great conditioner, but it doesn’t really help loosen the soil. It’ll keep your tomatoes from getting blossom end, though… and won’t effect pH.

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Agreed… All 100 facts… Well put @HorseBadorites

Here are some pics of plants grown in a very clayee red soil that got tested, and with a bit of compost and a top dress was absolute magic… So careful not to take out things you don’t know are actually there. The responsible thing to do would be to get your soil tested and go from there.
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This plant grew wild in compacted red soil… Grew like a monster

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