"TheScullster" wrote in message
...
Jane

The OP (original poster?) has been assimilating all the information from
the
wealth of responses gratefully received.
There appear to be a number of contradictions in the messages and other
web
material - to add sand or not to add sand etc.

A summary appears to be that if I throw sufficient organic material at the
clay base I may just get somewhere.
I intend to remove the blue/grey stuff which is very localised (about 1 sq
metre) and looks the most unhealthy.
Having done this and removed concrete topping etc I am left with about 8"
height to make up, so if I make this up with top soil I will have some bed
depth to play with before the plants reach the clay even without moving to
"raised beds".

The unanswered parts of the original question a

Will fresh manure break down by next spring?
Is 12" sufficient depth of workable soil for veg patch?

I am a wee bit woried that if you till the top 12", say, and leave the stuff
below it as compacted clay, you will find yourself with a drainage problem.
If I were young again, I would have done an old fashioned double dig on it,
and
would have incorporated every rolled up chunk of newspaper and/or all the
straw that I could lay
my hands on, into the lower spit. I did in fact do it once, and it worked
wonders.

How do I work out a weight of topsoil knowing the volume required to be
filled?

Take the uncompacted density of it to be approximately of 2,000 Kg per cubic
metre.

Franz