No-Dig Gardening

No-dig gardening

In no-dig gardening, the soil is never turned over; all manure, compost and other organic materials are applied to the surface.

Digging is such a common practice that it is rarely questioned, despite the fact that it is such hard work. In fact, it is possible to grow a full range of vegetables without even lifting a spade, and you certainly do not need to dig the ground between fruit and ornamental plants.


When to dig

Traditional reasons for digging include improving the aeration and drainage of the soil, and burying weeds and organic matter.

However, most soils do not become airless and waterlogged if they are not dug, provided they are mulched with organic matter. The material spread on the surface will gradually be taken into the soil by worms and other creatures, creating drainage channels and a good soil structure in which there is plenty of air.

digging can be detrimental to the soil Digging can in fact have a detrimental effect on the soil structure by disrupting the aggregates of soil particles and disturbing the soil life. It can also lead to the loss of organic matter from the soil by continually exposing it to the atmosphere where it breaks down more quickly. Loss of moisture from the soil is another disadvantage.

Digging is certainly a quick way of clearing ground that is covered in annual weeds. The benefit is short-lived, however, since below the surface of the ground there are hundreds of dormant weed seeds, all just waiting for the right conditions in which to germinate. When you bring them to the soil surface by digging over the ground, they will do just that. Instead, it is far more efficient to get rid of troublesome surface weeds by shallow hoeing or mulching with a non-degradable or biodegradable mulch. You do not even have to dig a new patch of ground — you can clear weeds or grass using a long-term mulch.

However, there are times when digging is beneficial. Soils that have been compacted or have a hard pan benefit fi an initial digging to break up the solid layer. Digging can also expose pests to predators and cold weather, so dig over any ground that you know is infested (for example, an old strawberry bed where vine weevil has been a problem) before you grow another crop.

Obviously, you need to dig holes in order to plant trees and shrubs, and you may want to grow some crops such as potatoes in the conventional way, or to dig in a bulky green manure such as grazing rye. There is no need to be fanatical about not digging, but be aware that over-cultivating the soil is not necessary and can be harmful.


To Dig or Not to Dig?

No Dig

Digging

Encourages the activities of soil-living creatures which do the digging for you

Hard work is required

Protects soil structure and produces friable soil surface

Can destroy soil structure

Protects soil structure and produces friable soil surface

Increases loss of moisture and organic matter from soil

Does not bring weed seeds to the surface

Kills annual weeds and surface-rooting perennials, but turns up weed seeds

Does not expose so pests to predators and cold

Exposes soil pests to predators and cold

Can take longer to improve poor soils

Breaks up compaction and hard pans.


Growing on a no-dig vegetable plot

If starting a new plot from pasture or weedy ground, clear it by putting down a light-excluding mulch for at least a growing season. This does not necessarily mean you cannot grow crops during this time: vigorous, widely spaced plants such as Brussels sprouts, broccoli and squashes can be planted through some mulches.

Once the ground is thoroughly cleared, growing on a no-dig system is easy. You will need the same amounts of compost, manure or fertilizers for individual crops as you would on a conventional plot, but instead of digging them into the soil, simply put them directly on the surface.

Remember to make sure that the soil is moist before you apply any mulch.


Sowing seeds on a no-dig bed

Crops such as carrots, beetroot, peas and parsnips can be sown directly in a seedbed on a no-dig bed, in the same way as on a conventional plot. If any compost or other nutrient-rich organic matter is required, it is usually easiest to apply it once the plants have become established and start to grow.

Before sowing, remove any weeds by hoeing the soil and rake aside any coarse remains of the mulch from the previous crop. Draw a shallow drill in the soil using a hoe. Water along the drill if the soil is dry and sow the seeds thinly.

On an established no-dig bed, the surface soil will be fine and crumbly and can be raked back over the drill. If the soil is cloddy, however, use leafmould or old potting compost for covering the drill. Firm the surface lightly with a rake.


Growing transplanted crops

Before planting out vegetable crops such as courgettes and brassicas, hoe the ground to remove weeds and spread compost, manure or other organic matter required by the crop on the surface.

Part the mulch where you want to plant and make a small hole with a trowel. Keep the soil removed separate from the mulch. Put in the plant and firm it in with the spare soil. Even out the mulch, but in general keep it 5-10cm (2-4in) away from the stem of the plant to prevent rotting.


Growing potatoes

This is the only crop that needs more mulching if grown on a no-dig system. The tubers are placed on the soil surface at the same spacing as on a conventional plot: typically 30-38cm (12-15in) apart in rows 38-50cm (15-20in) apart for early potatoes, and 38cm (1 5 I n) apart in rows 76cm (2-1/2ft) apart for maincrop. Layers of organic matter are used to exclude light: initially, cover the tubers with 7.5-10cm (3-4in) of moist hay or straw. When the plants are 20-30cm (8-12in) tall, add another layer of hay or straw the same depth as the first and top with grass mowings. Add grass clippings every so often throughout the season.

The main advantage of growing potatoes in this way is that they are so easy to harvest — you simply pull back the mulch and pick up the tubers from the soil surface without having to loosen and lift the soil around the roots of the plants. With new potatoes you can harvest the biggest without disturbing the plant and then replace the mulch to allow the rest to grow on. There is also some evidence to show that the mulch can help reduce tuber damage from potato blight.

However, in practice there are problems with this method and results can be poor. In cold areas, a light-coloured mulch can prevent the ground from warming up and may make the air above it even colder, so that frost is more likely to damage the foliage of the potatoes. Furthermore, because rain cannot easily get through the mulch extra watering may be necessary, and penetration of light through the mulch can give a high proportion of green tubers at harvest.

You can avoid some of these problems by planting the potatoes in holes. Use a trowel or dibber and dig individual holes approximately 15cm (6in) deep. You can either mulch the plants as before once they have come up, or make the planting holes through a black plastic mulch. If you use a type of good-quality, thick plastic, it should be reusable for several years afterwards.


Growing green manures

On an established no-dig bed the surface of the soil will be friable enough for you to be able to broadcast fine green manure seeds as normal. Larger green manure seeds should be sown in drills.

As an alternative to digging in, annual green manures can instead be hoed off or chopped down to ground level and left on the soil surface in the form of a mulch. One treatment will be sufficient to stop most of these regrowing, although grazing rye is likely to be a little bit more persistent. If this is indeed the case, an easy way of clearing the crop is to chop it down and cover it with a light-excluding mulch for a couple of weeks. This treatment is also necessary in order to incorporate longterm green manures.

28. January 2011 by Dave Pinkney
Categories: Organic Gardening, Soil Cultivation | Tags: , | Comments Off on No-Dig Gardening

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