THE ART OF IRRIGATION. 



CHAPTER XV. THE IRRIGATION OF HILLSIDES. WINTER 



IRRIGATION. 



. 



BY T. S. VAN DYKE. 



'"THE modes of applying water so far 

 1 given cover all ways that are gener- 

 ally justifiable in field, garden or orchard. 

 Special cases on small scales will often 

 justify the expense and trouble of sub- 

 irrigation and sprinkling. But one should 

 be cautious about deciding even this point. 

 There are lawns by the score in Southern 

 California that are flooded, yet look just 

 as fine and soft as those that are sprinkled 

 and do not take one-fourth of the water 

 or one-tenth of the trouble. It is all in 

 the laying out. The same with flowers of 

 all kinds. Whatever you can do by 

 sprinkling you can do more easily with 

 little furrows or basins around them pro- 

 vided you do it right and give plenty of 

 water when you give it at all. The idea 

 that the absorption of water by the leaves 

 makes them look brighter is old granny 

 nonsense. So while such things as straw- 

 berries could be kept clean by sub -irriga- 

 tion they can be kept just as clean by 

 setting them on high broad ridges between 

 deep furrows and filling the furrows with 

 straw or some good mulch. If the ground 

 is carefully laid out to even grade and the 

 furrows well made, the water, if fed evenly to 

 the furrows, will never rise above the mulch. 

 When you once admit that looks are of 

 no consequence, the problem of irrigating 

 hillsides is half solved. Yet it is mar- 

 velous how general is the idea that hills 

 cannot be irrigated and how stubbornly 

 the idea clings to the average skull. What 

 is today the most valuable, elegant and 

 profitable part of Redlands, California, is 

 slope that in 1887 was considered too 

 great for the use of water. And some of 

 the very best is land that three years later 

 when the orchards were fast scaling the 

 heights was still thought too rolling to be 

 of use. The Indian and the Mexican had 

 for a hundred years grown rows of trees 

 along ditches running along steep hill- 

 sides and in this way raised some of the 

 finest fruit. And still the white man did 

 not see that the principle could be extend- 



74 



ed to several furrows instead of one and 

 to a whole orchard instead of a single row 

 of trees. And outside of California you 

 will be called crazy today for intimating 

 that slopes of even one to one can be irri- 

 gated. Yet fine orchards stand on slopes 

 almost as bad as that today and they are 

 not terraced either. 



All you have to do is to abandon all 

 ideas of quincunx or any other symmetrical 

 form and plant the trees around the hill 

 on those lines on which the water will run 

 best. First the whole should be graded 

 to a face or faces of uniform slope as in 

 any other land. Then the lines running 

 lengthwise of the hill on which the water 

 will run may be determined, by trial, by 

 simply letting the water follow the hoe as 

 the Indian builds his ditch. Having 

 found the slope on which it will run 

 without cutting or becoming muddy you 

 can continue in this way if you use care 

 enough or can go faster with a board and 

 a carpenter's level. Suppose you find 

 fifty-five feet to the mile about right. 

 This is about two inches in sixteen 

 feet. A sixteen-foot board beveled on one 

 edge until it is two inches wider at one 

 end than at the other, when set with one 

 edge horizontal will represent the slope 

 with the other edge. So if you keep the 

 upper edge level with a common carpen- 

 ter's level the lower edge will be the grade 

 of the furrow desired. Small mistakes 

 will not matter. Three strips of scantling 

 nailed into a triangle with a nail for a 

 plumbbob hanging from the apex are also 

 very good. Level the base of the triangle 

 and then find how much raising of one 

 end makes the plumbbob swing off, say an 

 inch from a mark made where the string 

 hangs when the base is level. You can 

 easily give any grade you want in this 

 way. You can also do the same by nail- 

 ing blocks on the end of the plank instead 

 of beveling but it will be harder to follow 

 than the others, which give the exact 

 line of the bottom of the furrow. 



