108 



THE IRRIGATIONAGE. 



matiou contained in these descriptions the writer is 

 indebted to Mr. F. H. Tibbetts, a student in irrigation 

 at the University of California. 



The trees of orchards are about twenty feet apart, 

 set in squares or in diamonds, 108 trees to the acre. 

 In some of the younger orchards, particularly cherry 

 orchards, the trees are spaced farther apart. The most 

 common practice is to form a square basin around each 

 tree by throwing up ridges midway between the rows 

 of trees in both directions. These ridges are made with 

 ordinary walking plows, to which extension moldboards 

 are sometimes attached. Usually two furrows are 

 thrown together, the second furrow reinforcing the 

 first and making it higher. 



On light, sandy loams and all ordinary soils that 

 are not too wet or lumpy an implement known as the 

 "ridger" is commonly used to form the ridges (Fig. 

 19). The narrow, deep runners are made 'of 2-inch 

 planks and arc from fourteen to eighteen inches high 

 and from five to eight feet in length. They are from 



Fig. 21 Irrigating Orchard by Basin Method. 



four to five feet apart at the front end and from fifteen 

 to twenty-four inches apart at the rear end. The run- 

 ners should be shod with steel on the bottom and on 

 the inner side part way up to prevent wear and lessen 

 the draft. The runners are held in position by cross- 

 pieces on top and straps of steel. A steel ridger, 

 which is claimed to be superior to the ordinary wooden 

 ridger, is shown in Fig. 20. 



On light, sandy soils, which are free from weeds, 

 good ridges can be formed with the ridger alone. One 

 man with three horses can ridge twenty acres in ten 

 hours. On compact soils and those covered more or 

 less with weeds a strip must first be plowed and har- 

 rcrwed. Disk harrows and 1 disk plows combine both 

 operations and are much used for this purpose. The 

 loose earth is afterward thrown up by a ridger. 



The combination rotary disk, a recent design, is 

 highly praised by those who have used it for making 

 checks or ridges. It consists of four ordinary disks, 

 arranged in the form of a V to throw the earth toward 

 a common. ridge in the center. It requires from four 

 to six horses to operate it successfully, but time is 

 saved over the common ridger in not having to pass 

 along the same ridge more than once. 



When an orchard is cross checked or ridged by 

 first making ridges at right angles to the direction in 

 which the water will flow, and afterward in the direc- 



tion of flow, openings are left at all points where 

 ridges cross. Each basin is thus open at each of its 

 four corners. The most laborious way to fill these gaps 

 is by the use of the shovel. The common scraper, 

 drawn by one horse, is also used for this purpose. The 

 horse walks along the side of the continuous ridge and 

 as each cross ridge is reached sufficient earth to fill the 

 gap is dumped. 



A rotary scraper recently invented to fill basin 

 gaps was extensively used in the Santa Clara Valley 

 last summer. It differs from the ordinary scraper in 

 that the scoop is free to revolve about two fixed points 

 in the frame instead of being attached rigidly to the 

 handles (Plate IV, Fig. 1). It is filled in the usual 

 way, and when the gap is reached the operator releases 

 the catch at the handle, which dumps the scraper, after 

 which it is again snapped back into position to be 

 filled. 



There is no fixed rule as regards the height of 

 ridges. The lowest are usually eight inches high, with 

 sufficient base and top width to retain water in the 

 basin to a height of four inches. Some orchardists 

 apply as much as nine inches in depth over each basin 

 at one time, and in such cases the ridges need to be at 

 least twelve inches high. On nearly level ground, two, 

 four, sixteen or even a much larger number of frees 

 may be included in one basin. This practice . requires 

 higher and stronger ridges. 



FLOODING BASINS. 



As a rule, permanent supply ditches extend across 

 the upper end of the tract to be irrigated. Plumes 

 made of wood and cement concrete are also being in- 

 troduced with beneficial results to take the place of 

 earthen ditches. In some orchards these supply ditches 

 are temporary, like the ridges, and are made by plow- 

 ing out a dead furrow as deep as possible and then 

 scraping it out with a V scraper. If a larger ditch is 

 required, it is plowed and scraped out a second time. 



Perhaps one of the best methods of conveying 

 water from the supply ditch to the basins, is to make 

 double ridges .in the alternate spaces between the rows 

 of trees in the direction of the greatest slope, as in- 

 dicated in Fig. 21. The water in the supply ditch is 

 checked and diverted down one or more of these small 

 ditches. When the flow reaches the lowest tier of ba- 

 sins, an opening is made in each ridge and the water 

 floods the two adjacent basins. When these have re- 

 ceived sufficient water, other openings are made oppo- 

 site the next higher pair of basins and the flow is 

 chocked, so that it will be diverted into them. This 

 operation is continued until all the basins on both sides 

 of the ditch are flooded. The most convenient means 

 of .checking the flow in both kinds of ditches is by can- 

 vas dams. 



THE IRRIGATION AGE, 1 year . 



THE PRIMER OF IRRIGATION, a finely illustrated 

 300-page book 



Address, IRRIGATION AGE. 



112 Dearborn, Street Chicago. 



