Zero Dig

This re discovered concept involves minimal/no digging. It is championed by Charles Dowding in the UK. His books and videos are full of test data on the benefits of no dig.

The RHS are also now trialing no dig at Wisley in their allotment & world gardens.

What is no dig

For an established allotment, a 20mm layer of compost/mulch is spread each autumn across your no-dig area. The worms do the work taking the compost into the ground. The quantity of compost matches what a dig approach would put in for double cropping.

For a new area it’s possibly best to do a gradual process to go to no dig. Brambles and dock roots have to be dug out. For general weeds including bind weed, couch grass, etc double cardboard and a 2-inch layer of compost / mulch could be used if you don’t plan to use until next year. A 3-inch mulch/compost layer would be applied over cardboard if you want to plant that season. This is a lot of compost to make in one go. We had dug most of our allotment before we came across no dig, so we transitioned a dug allotment to a no dig allotment.

There is no particular crop rotation pattern applied although 6 months is recommended between harvesting a crop and planting the same crop in any area. Ground cover planting is done by always having crops growing. Weed little and often pulled out or hoeing as you see them.

As you are not digging wood chips can be used on paths. Surface wood chips have been shown not to cause problems with nitrogen depletion in the soil depth. If you were digging then any dug in wood chips would be likely to be detrimental to crop yield.

Amount of compost needed

At plot 31w on the Folly Lane site we don’t use compost under our soft fruit. We have about 68 square metres growing vegetables requiring (68 x 0.02) = 1.4 cubic metres of compost. Our current compost setup yielded 2 cubic metres of compost in 2022 and we are aiming to expand that to 3 cubic metres in 2023. Most will be from hot green/ brown heaps and about one third from a wood chip composting heap. For hot green brown materials, we use cardboard, well-rotted wood chips from our paths and well-rotted leaf mould from the communal heaps. We have a leaf mould stock in bags rotting down for next year when it is 14 months or more old. We put all weeds, old crops, etc onto the compost heap. We also incorporate grass cuttings from the communal paths along with weeds donated from neighbours' allotments. Wood chips for wood chip composting come from the site wood chip piles. We alos put small twigs in our wood chip composting system.

Pros

Yields supposedly around 10% above that when digging for equal amounts of compost. This is due to the benefits of not disturbing the bacterial and fungal growth in the soil that symbiotically helps with plant growth,
Soil physical structure with worm holes etc is not disturbed. (fewer problems with mud when wet and baked surfaces when dry).
One simple set of compost / fertilising rules regardless of soil types and crop types.
Predators of pests less likely to be killed than in a digging process.
Buried weed seeds don’t come to the surface so old weed seeds don't grow.
Wind born weed seeds on germination tend to be easy to pull out from the loose surface.
The layer of autumn compost/mulch suppresses wind-born weed seeds.
As not digging (and putting in compost) between crops two different crops in a season per area is possible.
You can ignore any stones on the ground.
Double cropping is made easier by minimum crop rotation protocols. The only rule is 6 months between removing a crop and planting the same crop in the same area.
Wood chip path surfaces become part of your growing area as over the long term (years) providing nutrients to neighbouring plants.
Does not need any spacial adjustment of soil chemicals between crops. Just apply a compost layer each autumn.
Weeds are removed by just light hoeing or pulling out from the loose surface.
Crop roots are left in the ground to add to the organic matter content (potatoes, carrots, parsnips, and other root crops are obviously removed)

Cons

Needs a lot of low seed compost on hand for the autumn. Quantities though only match what most people should dig in for two crops based on recommended levels.
To start in new areas if you want to plant/grow that season then cardboard layers and very thick 3 inches of compost/mulch are recommended which is a lot of compost.
Some people like digging and regard it as good for you if done with the right tools. Greenhouse/germination location needed to bring on seeds in plugs to facilitate double planting and cropping.
Compost really should be seed and root free from a hot composting system, or you just have to weed a lot in spring.
Needs seeds to be sown in plugs/ pots that are transferred to the plot using a dibber technique.
As you leave stones in the ground you may get fewer straight carrots and parsnips.

Tim & Liz have been on a no-dig course and are happy to pass on the principles that are being trialed on plot 31W.