300 THE IRRIGATION AGE. 



cause some discussion and agitation of the question. I cannot expect 

 much else, on account of the purely local application of the 

 points I shall mention to you. 



In districts where water is scarce, discussion on methods of appli. 

 cation usually have to do with economy in use of water, and in dis- 

 tricts where water is plentiful, the limits and beneficial results of its 

 application are the points at issue. In this, as in most questions, 

 some very valuable lessons are learned by a study of extreme con- 

 dition^. 



The investigations of the California station during the unusually 

 dry season experienced in that State last year, are very interesting 

 and instructive, and I mention some of the points they noted, in hope 

 that they may be at least suggestive. 



In the first place, the successful growth of some of their trees 

 with such a small amount of water led to an investigation of the con- 

 ditions of these successes, as well as the failures. The results of this 

 investigation are given in bulletin ] 21 of the California Experiment 

 station, from which I shall take a number of points for discussion. 



The deeper range of the roots in some trees than in others^ 

 whereby they may draw moisture from a larger bulk of the moist soi. 

 is given as the main cause of the success in tiding over the drought, 

 A case is given where the roots of a prune tree penetrated to a depth 

 of more than eight feet, where they had practically an unlimited sup- 

 ply of moisture, and were independent of the surface conditions as far 

 as moisture was concerned. It seems to me that the example is a sim- 

 ple one, and that the only conclusion the irrigator can draw is, that 

 he should do all he can to encourage deep rooting. It is a well-known 

 fact that roots follow moisture, and if the moisture is applied near to 

 the trunk of the tree so that it will penetrate deep into the ground, 

 the roots will follow it for their supply of moisture, and the result will 

 be deep rooting to an extent compatible with the ability of the sub- 

 soil to furnish the necessary nutrition, whereas if a great area around 

 the tree is irrigated to a slight depth, the same reasoning will bring 

 the roots near the surface and the moisture will be subject to th * 

 losses by evaporation. 



In southern California the water is carried to the tree in pipes, us 

 ually of concrete, and by means of an opening near the tree, supply it 

 with water. By this means they are able to irrigate thirty acres with 

 three inches of water, or ;in equivalent of 500 acres per cubic foot per 

 second. Whereas, in the same locality, where all the space between 

 the trees is irrigated, a much less area can be irrigated, and the roots 

 are spread out, and near the surface. 



Now, irrigating near the plant may not always be practicable, but 

 in the case of t ees it seems to me that we might safely say that where 

 the soil is a foot deep, we should apply the water so as to make the 

 roots penetrate a foot, where the soil is five feet deep, apply the water 



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