Roots follow moisture. — Very striking examples of deep rooting as 

 ihe result of vertical moisture penetration can 03 observed in some of 

 our native trees, which, while naturally at home on moist ground, are 

 nevertheless sometimes found forming luxuriant clumps on the slopes 

 and even summits of our coast ranges and foothills. If we examine 

 the ground where this occurs in the case of California laurel, we will 

 generally find that the soil in which they grow is underlaid by slate or 

 shale standing on edge, into the crevices of which the roots penetrate, 

 wedging them open ; while themselves flattening out, and thus pene- 

 trating to moisture at considerable depths. The same" may be observed 

 in the case ef the erect " bedrock" or foothill slates of the Sierra, on 

 which native as well as fruit trees flourish in very shallow soils, some- 

 times reaching permanent moisture at the depth of ten or more feet 

 below the surface. It can readily be observed during rains that there 

 is comparatively little run-off from the surface of these lands underlaid 

 by vertical shales. 



On the same principle, the grape vines which bear some of the 

 choicest raisins of Malaga on the arid coastward slopes, are m*\de to 

 supply themselves with moisture, without irrigation, by opening around 

 them large, funnel-shaped pits, which remain open in winter so as to 

 catch the rain, causing it to penetrate downward along the tap-root of 

 the vine, in clay shale quite similar to that of the California Coast 

 Ranges, and like this latter, almost vertically on edge. Yet on these 

 same slopes scarcely any natural vegetation now finds a foothold. 



Similarly the " ryots" of parts of India water their crops by applying 

 to each plant immediately around the stem such scanty measure of the 

 precious fluid as they have taken from wells, often of considerable 

 depth, which form their only source of water-supply. Perhaps in 

 imitation of these, an industrious farmer has practiced a similar system 

 on the high benches of Kern River, and has successfully grown 

 excellent fruit for years, on land that originally would grow nothing 

 but cactus. Sub-irrigation from pipes has been applied in a similar 

 manner. 



The principle flowing from the above is simply that the most 

 economical mode of using irrigation water is to put it " where it will do 

 the most good," close to the stem of the plant or trunk of the tree, and 

 let it soak downward so as to form a moist path for the roots to follow 

 to the greatest possible depth. It is this deep penetration to natural 

 moisture, as a matter of fact, which enables the small quantities sup- 

 plied to produce such marked effects. 



Basin irrigation. — It will be noticed that this principle is practically 

 the same as that of the basin irrigation of orchards, which was 

 originally largely practised in California, but has now been mostly 

 abandoned for farrow irrigation. The latter has been almost univer- 

 sally adopted, partly because it requires a great deal less hand-labour, 

 partly under the impression that the whole of the soil of the orchard 

 is thus most thoroughly utilized ; partly also because of the injurious 

 effect upon trees produced at times by basin irrigation. 



The explanation of such injurious effects is, essentially, that cold 

 irrigation water depresses too much the temperature of the earth 

 immediately around the roots, and thus hinders active vegetation to 

 an injurious extent, sometimes so as to bring about the dropping of 



