Lousy soil

[Grumpy Git]

The soil on my allotment is awful. I dug an area over with the spade and two days later I had clods that were as hard as concrete!  I think I'll be smashing these clods with a spade or fork, unless anyone can suggest another way to break them down.

[Grumpy Git]

[Palustris]

If your soil is clay, as it sounds then get one of those cheap soil testing kits and use it to estimate how much lime to add to make your soil slightly on the alkaline side (which most vegetables like). Lime causes the particles of the clay to stick together (flocculation)and this strangely enough makes the huge clumps fall apart. (John Miller will no doubt cringe at this simplistic explanation).
Then you also need to add humus, manure, compost, spent hops (good for clay) green manure dug in, anything organic.
If you wish for a more expensive addition, then sharp sand is useful, but it must be really sharp, full of bits of odd shaped gravel. (Run your fingers through it, if it cuts you then it is sharp enough, if it feels like silk then forget it!)
One good point about clay soil (if indeed this is what you have), is that it holds plant nutrients better than sand or silt, so whatever plant food you put in it remains available to your plants rather than washing out as it rains.

[Moggle]

No use to you now, but I have similair clay soil, and dug 3 beds over roughly from Oct - Jan this year, and the frosts and rain broke it all down fairly finely on the surface.

My other trick has been to get my 8 and 10 year old brothers-in-law to have a good (well supervised) bash at it with a hoe, they loved it!

And I second the advice from Palustris re organic matter - get as much in as possible  :)