How to Break Down a Heavy Clay Soil

Heavy clay soil like this presents many problems, especially at this time of year. What on earth do we do with it? How can we break it down into a fine tilth so that we can sow or plant?





There are two ways to deal with any heavy soil:

• Leave it to the frost
• Let it dry out completely

LEAVE IT TO THE FROST

The best way to have handled a clay soil like this, especially during the winter we have just had, would have been to let the frost deal with it. Constant freezing and thawing would have broken down these large lumps of clay through expansion and contraction. This would have left it in a more manageable state.

For some reason, this ground has been turned over too late. Best to do the digging (or ploughing) before the hardest part of winter sets in, whilst the ground is still dry enough (or frozen enough) to stand on without causing compaction.


LET IT DRY OUT COMPLETELY

As clay dries out, it bakes harder and harder, shrinking in the process. Eventually, it fractures into large sticky clods which are seemingly impossible to break down further (If you look carefully, you can see these fractures just showing).

The golden rule with clay soil (or any other heavy soil, for that matter) is NEVER ATTEMPT TO WORK IT DOWN TOO FINELY UNTIL IT HAS DRIED COMPLETELY.

Yes, I know what you are thinking: 'If you can't break it down now, how are you going to do it when it has baked even harder?'

Simple - WATER IT. Get the hose pipe and give it a good soak (or let the rain do it for you, but you will have to be quick to respond).

The action of the water will release the ionic (chemical) bonds which are binding the clay platelets (the clay's equivalent of particles) together. It will then crumble in your hands. In other words, in the garden, all you need do is rake the surface. It will break down into a wonderful tilth as if by magic.

TOO EASY! WHAT'S THE CATCH?

This will only work if the soil is COMPLETELY DRY. Partial dryness, as in the photograph, is no good. And these clods are too large to dry out before the next rain.

The only way to work this soil is to break it down in stages:

Firstly, encourage the fissures (cracks) to split completely by using a fork or a spade. Break it down into lumps about the size of a small fist if you can. This will allow the sun and air to get into it better. Leave it to dry out.

Then come back to it when it has completely dried, and water it.

Don't be afraid to leave a few clods on the surface, if you have to. The seeds and plants will work around them to a large extent, and there should be some hot dry weather ahead to complete the process.

Most novice growers break down soil too much, causing it to pan (seals the surface) during the first heavy rain.

It's the old story: Don't be in too much of a hurry. Nature seems to have its own way of dealing with things.