The labor involved in true trenching has led to the development of a substitute operation called double digging. Here only a single-L
depth trench is opened and the earth wheeled to the finish line. Organic matter is worked into the bottom of the single-depth trench and topsoil from the second trench applied over this. Except for the wheeling of the soil from the first trench to the finish line, double digging actually requires no more physical effort than ordinary digging; in both methods, every clod should be turned completely over. With either trenching or double-digging, there is little tendency to develop a hardpan or "plowsole" deep in the soil because when the ground is worked in succeeding years, the spade or tiller will not penetrate to the depth previously reached.
Despite the saving in effort made possible by power-driven tillage equipment, I still like to dig by hand. There is something about this task which lifts it out of the class of drudgery, even though in turning over a thousand square feet of garden I may move several tons of soil. The smell of earth in good tilth, the sun and wind and the feeling of kinship with the world of plant life just cannot be duplicated by the chugging of a garden tractor.
Unfortunately, limitations of time and physical strength will not always permit us to use our muscles for soil preparation. With just so many hours in a weekend, we cannot afford to do a little at a time. Before we could finish the job the best time for seeding and planting would be past.
The gardener is, therefore, faced with the problem of selecting the most satisfactory form of tillage machinery, whether he buys it outright or hires his work done. Most present-day garden "plowing" is done by rotary tillers. These work on the principle of a revolving shaft to which are attached sharp tines that penetrate the soil as they make a complete revolution around the shaft. The tines tear out roots, trash and plant wastes, chewing them into small pieces and burying them in a loose, fluffy duff of soil. Any organic matter, fertilizer or soil conditioning material applied to the surface is thoroughly and uniformly mixed in.
Small home-sized power tiller units are available but are usually too low in power to do a good job of deep tilling. Six inches is about the maximum depth you should expect from these small units. Actually this is deep enough to loosen the soil for the roots of most garden plants, but not where large amounts of organic matter are to be incorporated. About eight inches is maximum for most larger units. Both sizes are adjustable so they can cultivate from a fraction of an inch in depth, down to their maximum depth.