140 



THE IRRIGATION AGE. 



PREPARING LAND FOR IRRIGATION AND METH- 

 ODS OF APPLYING WATER. 



From Bulletin 145, courtesy United States Department of Agriculture. 



The items in the following brief summary give 

 the cost per acre for orchard irrigation under the gravi- 

 ty canals of the Santa Clara Valley : 



(Continued.) 



Another way of applying water to basins is indi- 

 cated in Fig. 22. The water from the supply ditch 

 passes through the basins from top to bottom in a zig- 

 zag course, due to the position of the gaps in the 

 ridges. Only half of the gaps need to be filled before 

 water is admitted, but those remaining are usually 

 filled immediately after each basin is flooded. This 

 method is objected to for the reason that the basin.- 

 nearest the supply ditch receive the most water. 



Still another method used under gravity canals 

 where water is more abundant is to make the basin 

 complete, then turn the water into the upper basin 

 and allow it to flow over the dividing ridge into the 

 next basin, and so on until the row is under water. The 



Fig. 23 Method of grading interior of basins to prevent water coming in 

 direct contact with trunk of trees. 



irrigator then begins at the lower end and repairs the 

 breaks, leaving each basin full of water. In a few 

 hours the soil absorbs the whole amount. 



All of the basins, ridges, checks, etc., just de- 

 scribed are temporary. After heavy rains and after 

 each irrigation the orchards are thoroughly cultivated 

 and harrowed and the ridges are worked down to the 

 general level to be rebuilt for the next irrigation. 



Some of the orcharists consider it detrimental to 

 have the water come in contact with the stems of the 

 trees. To prevent this those who are of this opinion 

 form two ridges between the rows of trees. This forms 

 small basins, in the centers of which the trees stand, 

 the water being applied to the outer basins. This pre- 

 vents water from coming in direct contact with the 

 tree and leaves the soil around it in good tilth. Nearly 

 the same benefits may be obtained by the common 

 basin if care is used in grading the soil within each 

 basin so that the circular portion around each tree 

 will not be submerged. The sketch shown in Fig. 23 

 may convey a better idea of this custom. 



According to the report submitted by Mr. Tib- 

 betts, the cost of preparing the surface is small in com- 

 parison with the cost of the water and the expense in- 

 volved in applying it. The water, which is conveyed 

 and delivered by canals, is never measured to the con- 

 sumer. The canal companies charge each taker from 

 $15 to $20 per day for a "head" of water, which varies 

 according to the conditions from two to three and one- 

 third cubic feet per second, or from 80 to 133 miner's 

 inches under a 6-inch pressure. 



The average annual cost of water on 130 orchards 

 was $2.50 per acre. 



The cost of preparing the surface in one of the 

 ways previously described was found to be, on an aver- 

 age, 68 cents per acre. 



Two men are generally required to attend to the 

 water. They work twelve hours each day and receive 

 in wages from $2.00 to $3.00. About 20 per cent 

 higher wages are paid for night shifts. The average 

 cost of applying water on 130 orchards was $1.88 per 

 acre. 



Fig. 24 Details of construction of 8-inch cement star d. Method of closing 

 dischaige is described elsewhere. 



Per Acre. 



Average cost of water $2.50 



Average cost of preparing the surface . . .68 

 Average cost of irrigating 1.88 



Total average cost $5.06 



USE OF METAL PIPE AND CANVAS HOSE IN IRRIGATION 

 OP FIELD CROPS IN CALIFORNIA. 



There is no section in the arid West where so much 

 skill is shown in irrigating field and orchard crops as 

 in southern California. In this section water is made 

 to do the highest duty possible and all irrigation prac- 

 tice tends toward the greatest economy in its convey- 

 ance and use. 



LARGE. COLLAR 



Fig. 26 Methods of arranging collar connection at ends of canyas hose. 



The water supply of the San Bernardino and ad- 

 jacent valleys is derived, to a large extent, from natural 

 streams which, during the rainy months, are subject 

 to heavy flow, but which during the dry season dis- 

 charge in many cases no water whatever and leave the 

 irrigated lands dependent upon such water as may be 

 stored or upon the supply derived from artesian 

 sources. In the great majority of cases it has been 

 found profitable to construct impervious channels, 

 either by lining the canals with cement or by the use 

 of underground pipes, and so reduce all losses to a 

 minimum. The water is drawn from the underground 



