THE ART OF IRRIGATION. 



CHAPTER VIII. 



CHOICE OF METHODS (CONTINUED). 

 ARATION OF THE GROUND. 



PREP- 



BY T. S. 



NOTE [As the publication of this ser- 

 ies has been suspended some fifteen 

 months the reader may have to go 

 back over some of the ground passed over 

 before fully understanding this. The first 

 seven chapters were mainly introductory, 

 dealing with the errors of the early irriga- 

 tors to a large extent because experience 

 has shown that almost every one if left to 

 himself will follow exactly in their foot- 

 steps. The study of error is as valuable 

 as the study of going right, and every one 

 should read the history I there gave. 

 Those chapters contained also a large 

 amount of facts necessary to a full compre- 

 hension of what is to follow and too num- 

 erous to repeat. Those who have not read 

 them must therefore attend more closely 

 to what follows, for it will be the more 

 practical part, or how to do it as dis- 

 tinguished from how you don't do it.] 



Next to the quantity of water at your 

 service, the size of the irrigating head in 

 which you can have it, and the length of 

 time you can allow it tq run, the slope of 

 the ground becomes the most important 

 factor in determining the method of apply- 

 ing water. If the slope is great you can 

 not flood by checks of any reasonable size. 

 If they are very small their number be- 

 comes a nuisance in making and in hand- 

 ling the water from one to the other. If 

 not small then the water stands too deep 

 and too long in the lower part; and too 

 much puddling, with compression of the 

 soil, is the consequence, besides uneven 

 wetting. All these are to be carefully 

 avoided where possible. The slope may be 

 so great as to compel you to terrace if the 

 nature of the product will justify the ex- 

 pense. If the soil is easily worked it may 

 pay to terrace some on a very light slope, 

 making the terraces very broad. This 

 may pay even for alfalfa. If terracing 

 will not pay you may then be driven to the 

 use of basins or rings around the tree or 

 vine where the slope is great. On such 

 ground you can do little with large heads 

 of water for a short run but must in some 

 way work with small streams with a long 



VAN DYKE. 



run. And as a rule it will rarely pay 

 to bother with anything but trees, vines 

 or vegetables on ground having very much 

 slope. Alfalfa and grain can be grown on 

 it but they will not generally pay except 

 for home use on a small scale. 



Good drainage in irrigation is almost as 

 essential as water. Where the drainage 

 is bad you must avoid flooding if possible 

 and use small streams or you may have a 

 sour, cold soil, with alkali perhaps appear- 

 ing on the surface when it dries and becom- 

 ing constantly worse. On the other hand, 

 if the ground contains alkali, which rises 

 to the surface in quantity sufficient to be 

 injurious, flooding is often the only way it 

 can be removed. If there is sufficient slope 

 to carry water rapidly off, ground that has 

 become badly alkalied may be put in good 

 condition by a quick flooding that will dis- 

 solve all the alkali on the surface and then 

 letting it run off as fast as possible. And 

 if very liable to alkali it should be laid out 

 so that it can be flooded in this way if nec- 

 essary. But drainage must still be pro- 

 vided if possible. You must remember al- 

 ways that in irrigation, however slowly or 

 carefully done, if done on a scale large 

 enough for a commercial success, a much 

 greater quantity of water is put upon the 

 ground in a given time than is usually 

 done by the clouds even when unusually 

 generous. And in the course of the year 

 one who has any kind of a respectable 

 water supply will generally put more into 

 the ground and have more run off of it 

 than will be the case from rain in the 

 wettest parts of the country. Therefore 

 there must be provision for the water to 

 run away beneath if possible, or, if the 

 soil is not naturally well drained, care 

 must be used in putting water into it so 

 that there be no excess. Waste water 

 ditches above ground must be provided 

 for what runs away and all rights of way 

 should include these for individuals as 

 well as companies. 



There is a distinction between " alkali 

 land " and land liable to alkali that should 

 be kept in mind, though the difference is 



