Making and maintaining a soil-mulch

After the land has been so well plowed that the rains can enter easily, the next operation of importance in dry-farming is the making and maintaining of a soil-mulch over the ground to prevent the evaporation of water from the soil.  For this purpose some form of harrow is most commonly used.  The oldest and best-known harrow is the ordinary smoothing harrow, which is composed of iron or steel teeth of various shapes set in a suitable frame. (See Fig. 79.) For dry-farm purposes the implement must be so made as to enable the farmer to set the harrow teeth to slant backward or forward.  It frequently happens that in the spring the grain is too thick for the moisture in the soil, and it then becomes necessary to tear out some of the young plants.  For this purpose the harrow teeth are set straight or forward and the crop can then be thinned effectively.  At other times it may be observed in the spring that the rains and winds have led to the formation of a crust over the soil, which must be broken to let the plants have full freedom of growth and development.  This is accomplished by slanting the harrow teeth backward, and the crust may then be broken without serious injury to the plants.  The smoothing harrow is a very useful implement on the dry-farm.  For following the plow, however, a more useful implement is the disk harrow, which is a comparatively recent invention.  It consists of a series of disks which may be set at various angles with the line of traction and thus be made to turn over the soil while at the same time pulverizing it.  The best dry-farm practice is to plow in the fall and let the soil lie in the rough during the winter months.  In the spring the land is thoroughly disked and reduced to a fine condition.  Following this the smoothing harrow is occasionally used to form a more perfect mulch.  When seeding is to be done immediately after plowing, the plow is followed by the disk harrow, and that in turn is followed by the smoothing harrow.  The ground is then ready for seeding.  The disk harrow is also used extensively throughout the summer in maintaining a proper mulch.  It does its work more effectively than the ordinary smoothing harrow and is, therefore, rapidly displacing all other forms of harrows for the purpose of maintaining a layer of loose soil over the dry-farm.  There are several kinds of disk harrows used by dry-farmers.  The full disk is, everything considered, the most useful.  The cutaway harrow is often used in cultivating old alfalfa land; the spade disk harrow has a very limited application in dry-farming; and the orchard disk harrow is simply a modlfication of the full disk harrow whereby the farmer is able to travel between the rows of trees and so to cultivate the soil under the branches of the trees without injuring the leaves or fruit.