[itsajungle]

Hiya,
I've just been very lucky to take on a plot! I'm very excited - I had a plot while I was living in Bradford, and after being on a waiting list in London I've just moved on to a plot that's clearly been well loved and cared for.
The past owners have left lots of that heavy black plastic material over some fairly weed-free, dug-over beds - I don't know when it went down, but it's over about a 1/3 of the plot, I'd guess. The soil underneath is really quite dense and compacted, very moist and rich, but also exceptionally heavy. I've never dealt with this before - would you recommend doing anything particular? I was going to take the covers off a few weeks before starting to plant anything in those beds and give them a light fork over. Would you recommend anything else for getting a better texture?
Cheers - great site! 

[Madame Cholet]

Personally if you are on clay I would  create 4 ft beds with paths and only walk on paths to avoid compaction.
Then just keep adding organic matter to the top of beds which will improve any soil structure.

[New shoot]

Congratulations on getting your plot 

It sounds as if you have some London clay under that plastic.  My plot is also fairly heavy clay based soil.  On a plus point, it is a fantastic growing medium once you get it into workable condition.  On the negative side, it can be heavy, dense soil as you have found.

I would get it roughly dug as soon as you can so it drains a bit.  The best thing then is to build lot of compost bins as clay will take as much compost as you like.  On areas where you are growing stuff that doesn't need fine tilth, this can be pretty rough old compost.  I dug a big patch over on Sunday where the squashes will be and  incorporated the contents of a couple of compost bins.  Its heavy work, but well worth it.  Straw based manure is another option if you can find a source close to you 

[Kristen]

I agree with the 4' wide beds, paths between, and never walk on the beds   I would dig out the soil from the paths and put it on the beds - just raising them a few inches, (or lowering the paths if you prefer ) will improve the drainage IME.

I'd dig a bit to see whether it is just heavy and claggy, or actually compacted (from having been walked on, over the plastic).  I'd also check if there is a hard pan under the top soil - e.g. if the plot was rotavated year-after-year, and if so I'd trench/double dig it to loosen the second spit in the process

Personally I'd then put the plastic back and plant-through for no-dig, no-weed and no-irrigate!

[sunshineband]

How fantastic to get a plot in good condition -- you are sooo lucky 

I can echo what others with a heavy clay soil have said already, but would add not the throw the plastic away. Once you have decided on how you are organising your plot and have dug over the planting areas, you could cover them again until you are ready to plant, to help warm the soil a degree or two.

Under the first ten inches or so of my soil there is a pan of compacted stones and gravel, which I have had to break up to help improve drainage... just check you don't have something like this. My plot is on a flood plain so the actual top soil is not that deep, but yours may well be much deeper.

[Goosegirl]

I would also add getting some sharp/coarse sand/grit (not builder's sand) and dig it in the bottom layers along with some mushroom compost which isn't expensive until you have made your own. Could you put your location in your profile as it helps us to give advice later on for where you live. Good luck! 

[ptarmigan]

Mushroom compost was really good on my clay soil, and yes, add as much organic matter as you can - so rotted leaves, home made compost, seaweed (in London...maybe not so accessible?). 

Also if you are trying to plant into the soil which is a bit rough and you don't have a fine tilth it can be worth growing on into small plants at home that will cope with that, and where you do want to put seeds, put a drill of bought finer compost down and sow the seeds into that to give them a start. 

[itsajungle]

Hello!
Thanks for all the awesome advice. Today I marked out some beds that I won't ever be standing on (I've been volunteering at a volunteer permaculture farm which has just one rule - never stand on the beds!' so I'll remember that one  )

A closer inspection today makes me think it isn't compacted, it's just heavy clay. My allotment site gets a regular delivery of horse manure (seems to be a mix of straw and wood chip based), and I've started piling that on nice and thick, especially for the brassica beds. I hadn't thought of mushroom compost, I'll look into that!

Thanks again - I'll start to use this site a bit more regularly, I think!

[itsajungle]

Oh, sorry to double post, but does anyone have any tips on a supplier for mushroom compost?

Cheers
Andrew

[New shoot]

Oh, sorry to double post, but does anyone have any tips on a supplier for mushroom compost?

Cheers
Andrew

Mushroom compost is just horse manure that has been used to grow a crop of mushrooms.  It still has a fairly coarse texture and that's why it is so good at helping to lighten up clay.

You can buy it bagged at a garden centre, but finding a bulk source may not be so easy.  The stuff you are getting delivered to site with straw and woodchip will be fine if you can't  find one or the bagged stuff works out too expensive for what you want to do.  I know permaculture requires good deep layers of organic matter

A well looked after plot and deliveries to site of some great soil conditioner.  You have been really lucky and should be able to grow some great produce on your plot 

[ptarmigan]

You might find the horse manure does the job. I use a mixture as the manure deliveries to our plot can be a bit erratic.

I get 60 blocks of mushroom compost delivered once a year that happily does all my no dig beds on a full size plot. I find it lighter and easier to deal with than the manure. We have a local farm that grows compost and delivers the by product which is the compost. It was £50 from memory for about half a small van full.  It's also quit alkaline which is good on chalk. 

But use whatever you can get esp if it's free!

[itsajungle]

Great, thanks! London Waste collect food and garden waste, turn it into compost, and sell it cheap or give it away for free sometimes, so I'm going to find out about that too. I heard it's not the most nutritious compost going, but the volume available makes up for that, especially when trying to loosen up clay soil. I'm going to see whether it's possible for the association wants to get a bulk load delivered.

And yeah, I'm feeling really lucky - the folks on the plot seem really lovely and welcoming, an active association, manure deliveries... seems like a good example of what an allotment site should be like, so far!

A

[Kristen]

I've had bulk deliveries of Mushroom Compost - they came on a whacking great big artic - not sure that would easily manoeuvre into an allotment, or that you could barrow it to your plot before everyone else thought it was a free for all!! Might be available in smaller loans of course ...

Pretty sure that Mushroom compost contains peat (used for capping), so basically horse manure that has been composted at high temperature (unlikely to be any surviving weed seeds) and some peat. It has a very fine structure.

I reckon you'll be fine sticking to the communal manure delivery your site has

If you are allowed to heap & compost it (rather than having to apply it direct to beds - I'm thinking "Heaping it" might be seen as hoarding??) then that would be good - give it time to rot down before being applied.

[Goosegirl]

Mushroom compost also contains lime which binds together the fine soil particles you get on clay and silt soils which will help with drainage.

[anchorman]

Itsajungle,

My plot is also heavy clay in south Northants. I've had it about 3 yrs and its slowly coming into shape.

Clay can be quite acid so probe with a soil tester to see if you need to fork any lime in. One thing i found works well is growing a hefty crop of potatoes helps to cultivate and subsequently break down the heavy clay. I found digging peat in was also helpfull. I would dig lime in if needed but well before planting spuds; you dont want scabs caused by direct contact with fresh lime.

In that heavy clay I plant spuds in Trenches, dug a full spade deep and make the bottom flat, then lay in a shallow layer of compost. After setting the seed potatoes I backfill with loose soil.

As the spuds show their haulms, I earth up a little but not to a large ridge; I found that the clay soil ridges clump and bake hard and dry out in the hot summer sun drying the new potatoes too much. At harvest time opening up the trenches carefully reveals lush tatties still down in the untrodden loose earth, no doubt hepled by the shading provided by top growth.

I hope you have a great time on the new plot.