PREPARING THE SOIL WITH SINGLE DIGGING
Soil that has been used for growing crops will be in a more or less fertile condition, according to the treatment it has received. It should be deeply dug in the autumn, and there are two ways in which this may be done. If the ground has recently been double dug, all that is necessary is to turn over the surface 10 in. of soil, I.e., one spade blade deep, or one spit deep. This is what we call single digging. The really important points to observe in dealing with soil in this way are first that each spadeful should be completely reversed, so that all weeds are buried—not just tipped on one side. Secondly, that the finished clot should be roughly level. Some people dig evenly and their plots remain level, while others tend to throw up soil into heaps in one place, and finish elsewhere with a shallow depression. Even digging should be aimed at, and if this is found difficult when single digging is done, a trench should be opened as for double digging, and the soil always turned into the previotr trench.
If the cultivated soil has not been well dug for some time, or has been only dug over as above described, it will benefit from double digging in autumn or winter. Double digging really means that the soil is broken to double the depth of the spade blade, but it also means that though the top spit is turned over it remains at the top, while the underneath soil is broken up well with a large digging fork, so that the roots can penetrate deeply, and so that moisture can pass freely through the lower soil.
It is quite easy to double dig a plot of ground if it is tackled in the right way. This is how to proceed. Begin by marking off a strip of soil 18 in. wide. If grass has grown over the plot, or if surface weeds are very rampant, strip them off to a depth of a in., and pile this mass of weeds on one side to be buried at the bottom of the last trench.
Then dig out the top spit of soil, and stack this also in a heap. If you can conveniently move these heaps at once to the part of the plot where digging will end, so much the better, but a tip to allotment cultivators is to divide the plot in two, dig the trenches across one half of the plot only, proceeding down one half and up the other, so that the digging ends near to where it began. You do not have to move the excavated soil from the first trench quite so far!
When you have opened your trench, which should go well down at the side, so that the bottom is square-angled, get into it, and clear out any loose, soil. Then take the largest digging fork, and with it break up the soil all along the trench. Over this loosened soil throw the surface turf and weeds from the next strip of soil, and any available organic manure (I.e., grass clippings, leaves, household refuse etc.), and finally fill in the trench by turning over into it the soil from the .next strip across the plot.
This of course will leave you with a second trench, alongside the first, which you will treat in exactly the same fashion, and so continue all down the plot, until at the end, you can fill into the last trench the weeds, and then the top soil taken from the first.
While you are digging you may come across large brickbats and stones : unless these are really very large indeed you need not remove them. Just drop them into the trenches below the organic refuse : they will help soil drainage, and will not harm crops. On no account try to remove all small stones from heavy stony soils or you will do more harm than good.
Trenching is a different matter from ordinary digging. It implies that the general position of the soil layers is altered. It is necessary sometimes on new land to get rid of surface rubbish left by builders, or deposits of unfertile clay, chalk, or gravel dug out during excavations for foundations or for drainage works.
It is generally pretty obvious if the infertile subsoil has been distributed over the top of the old soil, as the top fertile soil of any land is darker in colour, and different in texture from the subsoil, on account of the decaying vegetation, fibrous roots, etc., that it contains.
If you should find that some or all of the ground you have to dig is in this condition, I.e., with the fertile soil buried under rubbish or subsoil, trench the land at once, for to leave the infertile soil on the surface will ruin the chance of good crops for several years.
The procedure is not unlike that of double digging, with the exception that the trench must be opened to two spits deep, and the top infertile layer of the next strip thrown into the open trench first, and followed by the darker fertile layer. This will leave you, as before, with a well broken layer of infertile subsoil, and a top layer of darker fertile soil.
If you are breaking up what we call virgin soil, where turf forms the top layer, work exactly as described above for double digging, but as you mark out each 18-in. Width for digging, strip off the turf to a depth of 2 in., and throw this upside down in the open trench. The turf will decay and form excellent manure.