[Higster]

I today made a effort to dig a area of my plot which I have not touched yet, I have only had the allotment since Sept. It seems that I have a seam of clay how is it best to treat. Help please

[Trillium]

If it's just a thin seam, then work around it. If the whole area is clay, it'll need a few years of work. You'll need to find loads of rotted manure (checked that it doesn't contain aminopyrallid), loads of compost, shredded leaves and straw, some sharp sand and whatever else you can get to build the tilth. In this, I'd recommend you mark paths that you'll keep as paths and improve 'bed' areas only to save effort and supplies.

The other alternative is to build raised beds about 12" tall and fill the with good soil mixed with compost/manure. For this some folk purchase used scaffolding planks to cut costs, others manage to salvage free wood from places.

[Higster]

Thank youTrillium, I have raised beds on the other side of the plot, so that would seem to be the way to go.

[mumofstig]

That doesn't look too bad to be honest, working/digging it each year will make a huge  difference.
Specially if you leave it rough dug over winter for the frosts to work on it, and dig in a bit of compost/manure as and when you can, adding lime can also help break it up.
It makes very fertile soil with a bit of effort 

[Goosegirl]

You may have a clay "pan" where there is an impermeable layer on which your top soil lays. Dig in grit and sharp sand (not builders') in the lower layer for "instant" results to make a start for drainage improvement, then decide if you want raised beds (I did) and add lime to make the clay particles bind together as Trillium said. Clay can be acidic (do a pH test) so this, and/or adding spent mushroom compost which also contains lime and shouldn't be expensive for the amount you get, will also help. Add as much compost and well-rotted AP-free manure on the surface and leave for the worms and the winter frosts to work. You should have a reasonable tilth to sow seeds in next year. If you continually break up the clay clods on the surface and incorporate them with your grit, compost etc, you should soon have a good and fertile bed. Raised beds do need watering more than you think but that shouldn't be a problem if this year's summer is anything to go by!

[potatogrower]

i'd use a rotivator to break it up, add sharp sand, manure and cheap compost. moisten the clay by hosing water to ease the load on the rotivator and break and mix the lot up.

was wondering if the bigger peices could be moisten and used to make some pots. i've seen pots being made without a rotating table 

[yorkiegal]

my entire plot is like this and i couldn't afford to buy a load of topsoil. I double dug everything, added sand, mixed in a bit of compost and then whenever I planted anything I made a big hole and added more compost, chicken manure pellets and blood and bone and everything is doing fine in it. The plot is draining a lot better now and I plan to double dig again in autumn and add lots of manure. My plot was previously left untended for quite a few years.

[Higster]

Thank you all so much, the way to go is rotivate some compost and sand in, the soil is very wet, so hopefully I should be able to use the rotivator

[Yorkie]

I'm slightly concerned by the lighter orange coloured clay.  This can often be sub-soil, which is very difficult to work and has no nutritional value at all.

When you dig down, Higster, do you have a layer of darker clay and then you reach the layer of lighter clay?

[mumofstig]

I know that subsoil clay needs a lot of work for it to reach a state where it is easy for plants to access the nutrients in subsoil, but there are nutrients in it.
The subsoil is a 'zone of accumulation' where all the nutrients that leach down from the topsoil end up. Comfrey is one of a few plants that can access the nutrients from that layer and we access those nutrients by using the leaves in compost or as a liquid feed.
Subsoil usually just needs a lot of compost/manure added to it to increase microbial activity and digging/rotovating to aerate it sufficiently

[Yorkie]

Interesting point, MoS.

Certainly in my City and Guilds gardening course we weren't taught that; merely that it was nutrient-free and shouldn't be gardened.

[Higster]

I'm slightly concerned by the lighter orange coloured clay.  This can often be sub-soil, which is very difficult to work and has no nutritional value at all.

When you dig down, Higster, do you have a layer of darker clay and then you reach the layer of lighter clay?

The top layer on top is indeed dark and it goes lighter lower, will I need to remove this lighter clay

[mumofstig]

Interesting point, MoS.

Certainly in my City and Guilds gardening course we weren't taught that; merely that it was nutrient-free and shouldn't be gardened.

I just remembered stuff from my OU unit, back in the 80s, about soil and modern farming methods which were eroding topsoils and the required amelioration of the subsoil.

[gremlin]

Does garden lime break down clay??

[mumofstig]

Does garden lime break down clay??

Yes, as I mentioned above