method of soil treatment that will insure good germination.  For this purpose the summer fallow has been demonstrated to be the most desirable practice.  If the soil has been treated according to the principles laid down in earlier chapters, the fallowed land will, in the fall, contain a sufficient amount of moisture to produce complete germination though no rains may fall.  Under such conditions the main consideration is to plant the seed so deep that it may draw freely upon the stored soil-moisture.  This method makes fall germination sure in districts where the natural precipitation is not to be depended upon.

When sowing is done in the spring, there are few factors to consider.  Whenever the temperature is right and the soil has dried out sufficiently so that agricultural implements may be used properly, it is usually safe to begin sowing.  The customs which prevail generally with regard to the time of spring sowing may be adopted in dry-farm practices also.

Depth of seeding

The depth to which seed should be planted in the soil is of importance in a system of dry-farming.  The reserve materials in seeds are used to produce the first roots and the young plants.  No new nutriment beyond that stored in the soil can be obtained by the plant until the leaves are above the ground able to gather Carleton from the atmosphere.  The danger of deep planting lies, therefore, in exhausting the reserve materials of the seeds before the plant has been able to push its leaves above the ground.  Should this occur, the plant will probably die in the soil.  On the other hand, if the seed is not planted deeply enough, it may happen that the roots cannot be sent down far enough to connect with the soil-water reservoir below.  Then, the root system will not be strong and deep, but will have to depend for its development upon the surface water, which is always a dangerous practice in dry-farming.  The rule as to the depth of seeding is simply:  Plant as deeply as is safe.  The depth to which seeds may be safely placed depends upon the nature of the soil, its fertility, its physical condition, and the water that it contains.  In sandy soils, planting may be deeper than in clay soils, for it requires less energy for a plant to push roots, stems, and leaves through the loose sandy soil than through the more compact clay soil; in a dry soil planting may be deeper than in wet soils; likewise, deep planting is safer in a loose soil than in one firmly compacted; finally, where the moist soil is considerable distance below the surface, deeper planting may be practiced than when the moist soil is near the surface.  Countless experiments have been conducted on the subject of depth of seeding.  In a few cases, ordinary agricultural seeds planted eight inches deep have come up and produced satisfactory plants.  However, the consensus of opinion is that from one to three inches are best in humid districts, but that, everything considered, four inches is the best depth under dry-farm conditions.  Under a low natural precipitation, where the methods of dry-farming are practiced, it is always safe to plant deeply, for such a practice will develop and strengthen the root system, which is one big step toward successful dry-farming.