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. [Illustration: FIG. 284. THE DISK HARROW] Some experiments in wheat-growing have shown how readily water might be saved if plowing were done at the right time. Wheat sowed on land that was plowed as soon as the summer crops were taken off yielded a very much larger return than wheat sowed on land that remained untilled for some time after the summer crops were gathered. This difference in yield on lands of the same fertility was due to the fact that the early plowing enabled the land to take up a sufficient quantity of moisture. [Illustration: FIG. 285. RED KAFIR CORN IN SHOCK] In addition to a vigilant catching and saving of water, the farmer in these dry climates must give his land the same careful attention that lands in other regions need. The seed-bed should be most carefully prepared. It should be deep, porous, and excellent in tilth. During the growing season all crops should be frequently cultivated. The harrow, the cultivator, and the plow should be kept busy. The soil should be kept abundantly supplied with humus. Some crops need a little different management in dry-farming. Corn, for example, does best when it is listed; that is, planted so that it will come up three or four inches beneath the surface. If planted in this way, it roots better, stands up better, and requires less work.