To dig or not to dig?
Where possible, organic gardeners use green manures to protect the soil and reduce nutrient loss through leaching over the winter. But what about bare soil that can’t be treated this way?
The ‘traditional’ method
Rough dig and spread muck or compost over the ground. Unfortunately winter rains wash away a lot of the benefits of this nutrient, so I believe it’s best to apply them in the spring when growing plants will absorb the goodness. Most gardeners never have enough compost anyway, so the last thing you want to do is to see some of it being washed away into the rivers, causing problems there.
Is rough digging without a top dressing a good idea?
Yes,
especially with clay soils. Pests, like slugs and cutworms will be
brought to the surface and will be hoovered up by blackbirds and
attentive robins. Depending on the weather, an occasional dig over will
help clean up a piece of ground. In fact, there is no better pest
control than a small flock of hens or ducks working over the ground, as we have
in our kitchen garden.
Rough digging does also break up the soil. Frost will be able to
penetrate all the exposed surfaces, breaking them down to a finer tilth
by spring. Rough clods will not be compacted into an airless skin.
Remember healthy should consist of 50% soil particles: 50% air, so
compacted soil should be avoided.
What to avoid
It’s tempting to turn the soil with
a rotavater, but this can cause damage. The top 10 – 15cm of soil will
be finely worked, while everything beneath that is untouched. This will
lead to ‘panning’, with compacted soil lying on top of unworked loam.
Many people are tempted to use a black plastic sheet as a mulch. This
does prevent winter rains from beating down and causing compaction, but
it does also prevent birds from picking over and removing pests. A build
up of pests, like slugs, can easily be a result of this winter mulch.
How does no-dig work?
In the autumn, weeds are hoed down and covered by 5cm compost or leafmould mulch. A biodegradable mulch like cardboard or straw may be placed on top of this. A large worm population will be protected from marauding birds and the top layer of soil will be very fertile by the spring. It will also be fine, airy and friable – perfect growing conditions. There will be some disturbance when roots – carrots and potatoes – are harvested, and some argue that is enough disturbance.
But...
You will need large quantities of
compost. Leafmould rots down to almost nothing, so concerted dedication
results in a modest amount being available. How frustrating that so much
of this will be leached away over the winter months!
No-diggers argue that a ‘natural balance’ between pests and their
predators is achieved in the soil. I simply don’t believe that. My
experience over many years has shown that mulching often protects some
of the worst pests from their key predators.
And remember, rich soil can be just as bad as when it’s impoverished.
Soft, sappy growth will result from overfeeding and this will lead to
serious pest attack.
Conclusion
‘Balance’ should be the most
important word in the organic gardener’s vocabulary. No-dig plots
protect the soil, add nutrients [albeit at the wrong time] and help
improve its structure, but rough digging is equally important for
controlling pests and breaking down heavy soils.