Fig. 283. Protecting our Friends
It is an interesting study—the preparation of homes for the birds. Trees may be pruned to make inviting crotches. A tangled, overgrown corner in the garden will invite some birds to nest.
Wrens, bluebirds, chickadees, martins, and some other varieties are all glad to set up housekeeping in man-made houses. The proper size for a bird-room is easily remembered. Give each room six square inches of floor space and make it eight inches high. Old, weathered boards should be used; or, if paint is employed, a dull color to resemble an old tree-trunk will be most inviting. A single opening near the top should be made two inches in diameter for the larger birds; but if the house is to be headquarters for the wren, a one-inch opening is quite large enough, and the small door serves all the better to keep out English sparrows.
The barn attic should be turned over to the swallows. Small holes may be cut high up in the gables and left open during the time that the swallows remain with us. They will more than pay for shelter by the good work they do in ridding the barn of flies, gnats, and mosquitoes.
SECTION LXVIII. FARMING ON DRY LANDS
Almost in the center of the western half of our continent there is a vast area in which very little rain falls. This section includes nearly three hundred million acres of land. It stretches from Canada on the north into Texas on the south, and from the Missouri River (including the Dakotas and western Minnesota) on the east to the Rocky Mountains on the west. In this great area farming has to be done with little water. This sort of farming is therefore called "dry-farming."
The soil in this section is as a rule very fertile. Therefore the difference between farming in this dry belt and farming in most of the other sections of our country is a difference mainly due to a lack of moisture.
As water is so scarce in this region two things are of the utmost importance: first, to save all the rain as it falls; second, to save all the water after it has fallen. To save the falling rain it is necessary for the ground to be in such a condition that none of the much-needed rain may run off. Every drop should go into the soil. Hence the farmer should never allow his top soil to harden into a crust. Such a crust will keep the rain from sinking into the thirsty soil. Moreover the soil should be deeply plowed. The deeper the soil the more water it can hold. The land should also be kept as porous as possible, for water enters a porous soil freely. The addition of humus in the form of vegetable manures will keep the soil in the porous condition needed. Second, after the water has entered the soil it is important to hold it there so that it may supply the growing crops. If the land is allowed to remain untilled after a rain or during a hot spell, the water in it will evaporate too rapidly and thus the soil, like a well, will go dry too soon. To prevent this the top soil should be stirred frequently with a disk or smoothing harrow. This stirring will form a mulch of dry soil on the surface, and this will hold the water. Other forms of mulch have been suggested, but the soil mulch is the only practical one. It must be borne in mind that this surface cultivation must be regularly kept up if the moisture is to be retained.
Fig. 284. The Disk Harrow