It has been attempted in this chapter to demonstrate that water falling upon a soil may descend to great depths, and may be stored in the soil from year to year, subject to the needs of the crop that may be planted.  By what cultural treatment may this downward descent of the water be accelerated by the farmer?  First and foremost, by plowing at the right time and to the right depth.  Plowing should be done deeply and thoroughly so that the falling water may immediately be drawn down to the full depth of the loose, spongy, plowed soil, away from the action of the sunshine or winds.  The moisture thus caught will slowly work its way down into the lower layers of the soil.  Deep plowing is always to be recommended for successful dry-farming.

In humid districts where there is a great difference between the soil and the subsoil, it is often dangerous to turn up the lifeless subsoil, but in arid districts where there is no real differentiation between the soil and the subsoil, deep plowing may safely be recommended.  True, occasionally, soils are found in the dry-farm territory which are underlaid near the surface by an inert clay or infertile layer of lime or gypsum which forbids the farmer putting the plow too deeply into the soil.  Such soils, however’ are seldom worth while trying for dry-farm purposes.  Deep plowing must be practiced for the best dry-farming results.

It naturally follows that subsoiling should be a beneficial practice on dry-farms.  Whether or not the great cost of subsoiling is offset by the resulting increased yields is an open question; it is, in fact, quite doubtful.  Deep plowing done at the right time and frequently enough is possibly sufficient.  By deep plowing is meant stirring or turning the soil to a depth of six to ten inches below the surface of the land.

Fall plowing far water storage

It is not alone sufficient to plow and to plow deeply; it is also necessary that the plowing be done at the right time.  In the very great majority of cases over the whole dry-farm territory, plowing should be done in the fall.  There are three reasons for this:  First, after the crop is harvested, the soil should be stirred immediately, so that it can be exposed to the full action of the weathering agencies, whether the winters be open or closed.  If for any reason plowing cannot be done early it is often advantageous to follow the harvester with a disk and to plow later when convenient.  The chemical effect on the soil resulting from the weathering, made possible by fall plowing, as will be shown in Chapter IX, is of itself so great as to warrant the teaching of the general practice of fall plowing.  Secondly, the early stirring of the soil prevents evaporation of the moisture in the soil during late summer and the fall.  Thirdly, in the parts of the dry-farm territory where much precipitation occurs in the fall, winter, or early spring, fall plowing permits much of this precipitation to enter the soil and be stored there until needed by plants.