Engines are often used for pumping water from streams and transferring it to ditches or canals. The canals distribute the water over the land or over the growing crops.
[Illustration: FIG. 287. THE MAIN DITCH OF AN IRRIGATION PLANT]
None of these methods, however, can be used for watering very large areas of land. Hence, as the value of farm lands increased other methods were sought. Shrewd men began to turn longing eyes on the wide stretches of barren land in the West. They knew that these waste lands, seemingly so unfertile, would become most fruitful as soon as water was turned on them. Could water enough be found? New plans to pen up floods of water were prepared, and immense sums were spent in carrying out these plans. Enormous dams of cemented stone were thrown across the gorges in the foothills of the mountains. Behind these solid dams the water from the rains and the melting snow of the mountains was backed for miles, and was at once ready to change barrenness into fruitfulness. The stored water is led by means of main canals and cross ditches wherever it is needed, and countless acres have been brought under cultivation.
Water is generally applied either by making furrows for its passage through the fields or by flooding the land. The latter plan is the cheaper, but it can be used only on level lands. Where the land is somewhat irregular a checking system, as it is called, is used to distribute the water. It is taken from check to check until the entire field has been irrigated.
[Illustration: FIG. 288. THE PROCESS OF IRRIGATING CORN]
The furrow method is usually employed for fruits and for farm and garden crops. In many places the grass and grain crops are now supplied with water by furrows instead of by flooding.
Irrigated lands should be carefully and thoroughly tilled. The water for irrigation is costly, and should be made to go as far as possible. Good tillage saves the water. Moreover, all cultivated crops like corn, potatoes, and orchard and truck crops ought to be cultivated frequently to save the moisture, to keep the soil in fit condition, and to aid the bacteria in the soil. It was a wise farmer who said, "One does not need to grow crops many years in order to learn that nothing can take the place of stirring the soil."