Digging the soil helps to aerate it—although in a fertile soil earthworms do that task anyway. Digging is also necessary if you wish to incorporate bulky organic material and bury weeds. Perennial weeds are more readily removed from the soil as digging proceeds. Some gardeners do not dig at all. They rely on vast quantities of organic material placed on the surface to smother weeds, and a high earthworm population to take the organics down into the soil. Total weedkillers, which become inactivated when they touch the soil, are useful if soil is not dug.
My soil turned into lumps like house bricks after digging. What went wrong?
You have a clay soil, and it sounds as if you dug it over during late spring or summer. The sun and drying winds made the lumps go solid, and they became very difficult to break down. Clay soil should always be dug in autumn, before heavy rain sets in to make the clay sticky. Turn the soil over and leave the surface rough so that frost will shatter the clods. If your soil is too acid, you should apply lime (also in the autumn). Garden compost or other bulky organic matter is useful, but do not apply lime and manure at the same time. (Do not, of course, use lime where lime-hating plants, such as rhododendrons, heaths, and potatoes, are to be grown.
How deep do I need to dig?
Generally one spit is sufficient: that is, the depth of your spade blade or the tines of your fork. If the topsoil is less than one spit deep, then dig more shallowly: you must avoid bringing the subsoil to the surface. Deep-rooted plants benefit from deep digging if the subsoil is compacted, and it may be necessary to dig deep to remove a pan .
In order to dig the subsoil, or second spit (a method known as double digging), first dig out a trench one spit deep to gain access to the lower level. The subsoil is then forked over and the topsoil from the next trench to be dug is placed on top of it. The subsoil from the final strip is filled with the topsoil from the first trench.
Weeds are growing on my soil. Can I dig them in, or must I remove them?
Weeds are a useful source of humus, provided they are dug in before they flower. But you would be well advised to remove completely all deep-rooted perennial weeds, and those with creeping roots or stems.
Is hoeing really necessary?
Hoeing is carried out to cut through weeds, to loosen a caked soil surface so that air will circulate in and out of the soil, and to create a mulch of dry soil to conserve soil moisture below. It is an effective way of incorporating fertilizer into the soil; and soil pests are often chopped up as hoeing proceeds.
On the other hand, in a well-stocked bed, border, or vegetable plot, hoeing can easily damage the stems and surface roots of plants unless it is done very carefully. In such cases, a surface mulch is the better alternative. It will suppress weeds, conserve moisture, avoid caking of the surface, and will not bring weed seeds to the surface to germinate, as often happens with hoeing.
Is mechanical cultivation better than digging by hand?
On a plot of any size, mechanical cultivation is obviously quicker and far less tiring. But often it results in perennial weeds being chopped up—and thus effectively being increased. Soil structure can be harmed if the soil is tilled too frequently, and there is the possibility of creating a mechanical pan if a rotavator is used at the same depth each time.
Should soil be firm before sowing and planting?
As long as you have created a fine tilth, the soil should preferably be firm: loose soil is inclined to dry out too quickly in windy weather, especially in strong sun, and most plants require firm soil to establish their roots properly. In fact, certain vegetables, such as brassicas (the cabbage family), should be planted so firmly that it would be difficult to pull them up after planting without snapping off the leaf.
Seed beds should be firm enough to enable the seed to make good contact with the soil and to prevent it drying out. It is also far simpler to draw out a straight shallow seed drill in firm soil. The best way to firm the soil uniformly is to tread it over without leaving spaces between foot marks. Do nc firm wet soil, otherwise tilth and structure may be spoiled.
How can I level a sloping site?
You will need a digging fork, a spade or shovel, a wheelbarrow, several long stakes, a straight edge and a spirit level. First remove the topsoil and place it to one side, preferably away from the site to b< levelled. Next drive the stakes into the ground all over the site, the distance between each being slightly less than the length of you; straight edge. With the aid of the spirit level, make the top of each stake level with the others. You now have a guide to work to. Move the subsoil around the site until it is level in comparison with the stake tops. The topsoil is then returned.
