278 MISCELLANEOUS FARM SUBJECTS 



service. (F. B. 138; Ex. S. 1904; Y. B. 1895; Ex. S. A. R. 1908, 

 and Cir. 226.) 



In choosing land which is to be irrigated a careful examination 

 should be made of the character and depth of the soil, its behavior 

 when irrigated, the slope and evenness of the surface, the presence 

 of injurious salts, and the facilities for drainage. One of the best in- 

 dications of the character of the soil is the native vegetation which 

 grows on it. When sagebrush, 'buffalo grass, or cactus is found on a 

 tract, it is reasonably certain that the soil is fertile, easily tilled, and 

 well drained. The plants named are but a few out of a large group 

 which grow on good soil, easily irrigated. On the other hand, the 

 presence of greasewood, saltwort, salt weeds, or other similar plants 

 is indicative of a heavier soil, less easily cultivated, and containing 

 more or less of the injurious salts usually grouped under the common 

 name of alkali. 



In arid regions cultivated plants are deep rooted. They draw 

 their supply of plant food and moisture from considerable depths, 

 and the deeper the soil the larger is the feeding ground for the roots 

 and the greater is the capacity to store water. In the warmer parts 

 of the West the top layer of soil is used chiefly as a sort of blanket to 

 protect the moist soil beneath, which furnishes both food and water 

 to the fibrous roots. The presence of any hard, impervious stratum 

 lying between the first and fifth foot prevents deep rooting and the 

 storage of moisture. A hard stratum lying between the fifth and 

 tenth foot is likewise injurious, but to a less extent. On the other 

 hand, a porous stratum of coarse gravel may waste large quantities 

 of irrigation water by permitting it to percolate beyond the root 

 zone. It, however, insures good drainage, and is more desirable than 

 an impervious subsoil. The character of the subsoil may be readily 

 determined by boring holes with a suitable soil auger to a depth of 

 10 feet, if necessary, and taking samples of soil at different depths. 



Absorption of Water by the Soil. Easily irrigated soil will ab- 

 sorb sufficient water in twenty-four hours after an irrigation to be- 

 come moist to a depth of 2 or 3 feet. Some soils are so impervious 

 that it is difficult to wet more than a few inches below the surface 

 and others are so porous that the water soon percolates through them 

 beyond the reach of the deepest roots. The surface of other soils 

 bakes and cracks after each wetting, which renders cultivation dif- 

 ficult. It will usually be possible to find similar soils under irriga- 

 tion in near-by fields, 'but if this is not possible, a trial may be made 

 on a small scale to determine how the soil acts under irrigation. In 

 general, sandy loams irrigate well, while clay is hard to cultivate 

 when wet, does not absorb water readily, and bakes and cracks when 

 drying. 



Surface Conditions. The farmer should likewise examine with 

 much care the nature of the ground surface. The 'best conditions 

 are a smooth surface, with a uniform slope of 10 to 20 feet to the 

 mile. Such land costs little to put in shape for the spreading of 

 water over it, and the slope insures good drainage. At the other ex- 

 treme, one finds land full of buffalo or hog wallows. These alter- 



