clay soil improvement - what to do first?

I'm trying to start a Forest Garden in southern England, zone 9.

My soil is heavy clay. Some of it is pure clay - in places you can scoop it up and make pottery with it. Most is not that bad, it has some organic matter but is still very heavy and prone to waterlogging.
At the moment there are brambles (blackberries/briars), some ferns and some grasses growing.

I have selected a small area to start with. I have dug drainage ditches to relieve waterlogging. This is off-grid, so no power tools. A spade, a fork, a billhook, a wheelbarrow. That's it.

I'm not sure what to do first. At the moment, I intend to cut the weeds, dig horse manure into the top 6 inches, then plant soil-improver plants into that and leave it for a season.
It seems like some people just dump horse manure on top and let earth worms do the mixing work. Others use a mulch layer like cardboard to keep the weeds down while their edible plants are getting established. Others don't use animal manure but rely solely on soil-improver plants. I have seeds for comfrey, red and white clovers, buckwheat, Hungarian rye grass, vetch, peas.

My problem is not too few ideas but too many!

I've included a photo of how it looks now (it's a mess). Once spring arrives, those weeds will jump up to waste height.

So most of my experience is in OM rich Agg soils. But I'm playing with lots of clay now too.

One thing. Even a nice dense clay has the potential to turn into sticky gloppy muck with the addition of Organic Matter. It can also form awesome clay loams. Number one thing I think is to have a constant and fairly substantial organic mulch on the surface. Stuff that hasn't decomposed to muck yet. I'd also start toying around with the idea of char but that just me.

PS I have unlimited quantities of dead oak and hazel leaves I could use

I have some areas of thick solid white clay so I am also interested in your solution here. I have read that gypsum could be used to help loosen the clay up. In general I am skeptical that simply putting OM on the top will improve the clay in a timely manner. It would seem that a cover crop (e.g., clover and grasses), gypsum, compost and ripping/sub soiling would be a suitable recipe; though I don't have any experience with this approach...

Is it true that grinding up eggshells and turning into clay helps unlock it? I read it from a bio dynamic person somewhere once about calcium having this effect somehow. By the sound of it the author conveyed that egg shells ground up in a homeopathic manner as well as some other things. I've never tried it but would love to know if anybody here has tried it or knows more about it.

I can tell you what I have done, in hopes it will help you with a very similar situation. First, you're on the right track with drainage though its terribly exhausting work. If you can find a source for backfill (gravel, rock etc) then use it to backfill your drainage ditches. Worst case scenario use the leaves under tons of sticks, they'll help hold the drainage ditches in place for a few years until they decompose, then you've got compost! I'd suggest using the fill from the drainage ditches/paths to put on top of a layer of leaves already applied to your beds. In fact, I use my paths (the drainage ditches) as compost piles, my back hurts enough, hauling to and from a compost pile doesn't appeal. Once you've got the structure of your 'field'/'garden', now you're ready for a soil test. Likely greenstone sulphur and soft rockphosphate applied to the soil prior to mulching with all those leaves. Your soil tests will lead you in the right direction. Once you've got all that in, now its time to plant buckwheat, alfalfa, rye etc. You're after roots making their way into the clay for you! Do you have pigs? Pigs plus leaves might really make some quick work?

btw, you're best bet is really to use that clay, drainage ditches and surrounding dead fall to build hugel beds. Like so

The visible wood fills the void left from digging the drainage, the soil from it was mounded on top of two trees which is visible in the foreground

The first question is what do you want to have this land become short term and generations from now? Next step is to define in its entirety what you are managing. This includes identifying the available resources, including money, tools, labor etc... that you have at your disposal to reach those short and long term goals. I see you partly have done that, but you need to clearly define it as much as possible. The objectives, goals and actions need to be designed produce the quality of life sought, and what the life-nurturing environment must be like to sustain that quality of life far into the future. It's not just the clay we need to address, it's the whole context for your life, and future generations. By more clearly defining the whole, you can better devise a management plan.

"Permaculture is a philosophy of working with, rather than against nature; of protracted & thoughtful observation rather than protracted & thoughtless labor; & of looking at plants & animals in all their functions, rather than treating any area as a single-product system." Bill Mollison

Next you need an objective monitoring system, and that starts now. For example, you said you have clay, but what kind of clay? What exactly is the SOM content? Ph? How does it vary over different parts of the land? How does the vegetation vary? Have you actually measured it? So start off right now with a good soil test(s). That will give you a baseline to judge the effectiveness of your plan. Then make a map of the predominant vegetation and try to quantify it's density. Again for a base line. You will probably need to actually make assessments in each season on vegetation.

Next step is to put the plan into action. It is important not to limit the management tools you use. The eight tools for managing natural resources are money/labor, human creativity, grazing, animal impact, fire, rest, living organisms and science/technology. To be successful you need to use all these tools to the best of your ability. In any ecosystem regeneration plan, don't forget animal impact!

“As the small trickle of results grows into an avalanche — as is now happening overseas — it will soon be realized that the animal is our farming partner and no practice and no knowledge which ignores this fact will contribute anything to human welfare or indeed will have any chance either of usefulness or of survival.” Sir Albert Howard

In permaculture we always think about the crucial role animals play in the nutrient, carbon, water cycles. They can be wildlife, or domestic animals if wildlife is lacking, it even includes small animal impact like insects and worms, but the land absolutely needs animal impact if it has any chance of regenerating in your lifetime. Always remember that.

Next step is a simple tool for every decision you make. Just do this EVERY time. Write it down if you must. It is critical that this become a habit. All decisions, large and small must ask 6 things: Is this course of action socially, environmentally and financially sound short term? and: Is this course of action socially, environmentally and financially sound long term? Every course of action needs all 6 questions answered. Not all answers must be perfect, but they need answered, so you can identify where improvement is needed.

Get all that done, and then we can talk specifics. Until you do that though, it is hard for an outsider to give advise. I could for example recommend goats to clear the brambles, but are you allergic to goats? Is there adequate fencing? Is the land zoned for large farm animals? Do you have time to care for them properly? Do you have the money to afford both the goats and fencing and vet bills should they come up? All these questions you need to answer first from the above framework. Then if you decide goats are feasible, will you keep them long term? Maybe "renting" some goats is a better option than owning them. Get the idea?

Landon Sunrich wrote:

One thing. Even a nice dense clay has the potential to turn into sticky gloppy muck with the addition of Organic Matter. It can also form awesome clay loams. Number one thing I think is to have a constant and fairly substantial organic mulch on the surface. Stuff that hasn't decomposed to muck yet. I'd also start toying around with the idea of char but that just me.

Oh and roots and a canopy. Obviously.

Sounds like you've got plenty of advice to start chewing on, eh Paul?

Chop and drop the weeds, the problem is the solution, and if you can find any sand anywhere that helps.

I understand that adding sand to clay makes a concrete-like substance. In any case, there are numerous data sources around that warn not to do that. Again, this is not something that I've done, but I would be very cautious with that idea.

My garden was all clay when I started, I added and forked in, about three inches of sand on top and I pile all sorts of leaves on top each fall, never had any concrete.

Chris Barnes wrote:I understand that adding sand to clay makes a concrete-like substance. In any case, there are numerous data sources around that warn not to do that. Again, this is not something that I've done, but I would be very cautious with that idea.

It depends upon the type of sand being used. Yes, there are types to stay away from, but there are some very applicable, useful types as well for this situation...sharp builder's sand (I believe some refer to it as masonry sand).

I have clay too.
I dumped some mixed sand on and tried to turn it in as best I could then raked it fairly smooth. Then I freely broadcast many carrot and daikon radish seed and covered them over lightly with some compost. They did a remarkably good job of drilling their roots into the clay.
The daikon mostly grew above ground and were eaten by bugs but I got a few. Most carrots were too small to bother picking but a lot got to thumb size. They were mostly just too close together- I never thinned them. They were only there to break up the soil. I'll plant the same again next year and I think we'll have the beginnings of soil.

A layer of cardboard will do a lot at first to knock down the plants that are there now, should have had it there over the winter though.
If you have a bit of compost I would just spread plenty of cheap carrot, daikon and plain radish seed down, then cover lightly with compost and see what happens. Let them do the work for you.

Looks like we have the same clay as you do. It turns into really great soil eventually.

First off, yes clear the brambles, and dig out their roots, also any convolulous and nettles, although with diligence, they can be eradicated gradually later, so don't go digging just to get them out. Try not to tread the ground into mud while you're doing that! mark out beds 4ft wide by about 12-16 long, with paths 1-2 ft wide, then keep to those paths. If you can get old scaffolding boards, or broken concrete slabs to out on the paths, that will help keep muddiness under control too. Someone I've met (also on the same clay) uses compostable waste on the paths and moves the path a little every year.
I find potatoes make an excellent first crop, but my method is different from the usual. Most people suggest potatoes because it involves major soil disturbance three times in one year. Personally I don't think that's a good thing, especially if you're trying it on claggy clay! Not to mention breaking your back! Do NOT dig. Just leave the weeds (minus the nettles and convolvulus) where they are!
Can you find a source of large pieces of corrugated cardboard? In theory, you can use multiple thicknesses of newspaper, but cardboard is so much easier. Lay the cardboard/newspaper over the beds, overlapping the pieces to discourage gaps. Cover that with 6" or more of well rotted manure. It must be well rotted, not smelling of urine/ammonia. Compost is ok too, but you do need a lot. Plant the potatoes at the normal spacing, two rows to a bed, directly in the compost, don't make holes in the cardboard. (You can plant broad beans with the potatoes, too. ) when needed, to avoid walking on the beds, use a draw/onion/swan neck hoe to earth up. When you have earthed up as much as possible with the manure/compost, you can use those leaves as a final light proof layer. (Grass cuttings are the usual thing. ) When the potatoes are ready for lifting, use a fork rather than a spade, and just let the mulch get mixed into the soil, as you're picking out the spuds.
With enough compost/mulch you can even grow veg on concrete; you have the advantage that your clay will provide valuable nutrients to your plants!
Another low effort method to get you started is growing directly into straw bales, I haven't actually tried it but it ticks all the boxes. I have some neglected ground I need to cultivate, so I might get around to trying it this year.

HTH

Edited to add chalk or lime is more use than sand, as it chemically breaks up the clay as well as physically. A couple of hundred years ago they used a lot of it round here, brought up on sloops from Kent, when they changed from animal farming to wheat. You still see it used occasionally even now!

Second edit to add, choose soil improver plants that are simply cut and left as much rather than ones that need to be dug in.

We have clay - red, orange and white. I love the acidity levels and patience is foremost. Looks like you have lots of organic material to layer (although I would not use chopped brambles as they are impossible to get rid of and a blackberry stick will propagate around here). I started with a thick layer of newspaper (not a fan of the glues in cardboard), laid a thick cover of sawdust & chips from a local lumber mill and topped with dirt/compost, finishing with straw and planting every root crop seed & red clover I could get my hands on. After 3 seasons aka 1 year, of growing all kinds of annual herbs, veggies and flowers, letting the remains of the plant decompose into the soil and before winter took hold, I layered more sawdust & chips topped with compost and straw. I left that lasagna to heave all winter and the following spring started to implement my garden design and carve out very high beds & swales; this manipulation helped to mix in all of the layers and wick excess water away. The paths are covered with straw, which breaks down over the course of wear throughout the year and at year end, this broken down yummy straw is then spread on top of all of the beds for the winter. In the spring, the beds are topped with compost and a fresh layer of straw is put on the paths. Our soil is now deep, rich and wonderful. It took a few years, but we were still able to have decent harvests in the working stages of this. I still don't pull up spent plants between seasons, but chop & drop everything above ground level, leaving the roots to breakdown. Good luck - clay soil is great....eventually.

Paul,

My 1/2 hectare plot is also really heavy clay. The previous owner had grown alfalfa on it for 7 years, mowing it with heavy machinery (=compaction).

Initially I thought that by heaping organic matter (e.g., alfalfa hay and other herbaceous plants) onto the surface I could improve soil structure in the mulched area. After about 12 months under mulch, the covered areas improved only superficially - about 1/2 an inch of comparatively looser soil on the surface, but the same compact heavy clay underneath that. (In addition, the thick mulch attracted a population of field voles which multiplied like crazy and started attacking my newly planted trees.)

I tried to observe what my next door neighbours were doing (my neighbours are subsistence farmers who own small strips of land of a couple of hectares max; they have the same clay soil but really crumbly and nice !). What they do is - horror! - they plough the fields every autumn.

So last November I asked a local guy with a tractor to plough the area where my future veg garden is going to be. The winter frosts also lent a helping hand (we had minus 20 degrees Celsius this winter) by breaking down the big dollops that the plough had turned over. The result: soft rich soil over 1' deep. In order to keep it that way, I have divided the area into fixed beds separated by footpaths. So hopefully compaction will not return, and thus I will not need to plough or dig again.

Now, I know that in Southern England you don't have such severe frosts, and I'm not sure how heavy the frost must be to achieve that effect on clay soil, but it may be worth trying.

In addition, I have ordered a truckload of spent mushroom compost, which I intend to partly mix into the soil, partly spread onto the surface. I have had very good experience with mushroom compost on this plot (around trees and shrubs) as well elsewhere, in veg gardens.

I hope this helps.

Best of luck
Levente

I'm using nitro radishes and cover crops myself.