THE ART OF IRRIGATION. 



229 



other figure thrown in between true con- 

 tour lines. 



As thus run, some of these check lines 

 are nearly a mile long. The checks thus 

 formed run from about twenty acres up to 

 two hundred with an average as near as I 

 could judge of about forty acres. Near 

 Pozo, in Kern County, are several thou- 

 sand acres laid out by the eye by a China- 

 man who was an experienced irrigator. I 

 saw it under water and it was well enough 

 done, so well done that I am certain that 

 with a carpenter's level fitted with rifle 

 sights and a common tripod any one with 

 sense enough to take the height of the 

 instrument on a rod marked plainly into 

 feet and tenths of a foot, and with enough 

 arithmetic in his head to add or subtract 

 the readings from the height of the in- 

 strument, could lay out any ground well 

 enough for good flooding. 



The embankments made on these lines 

 vary in height from fifteen inches to 

 twenty or even twenty-four inches, the 

 average being nearly eighteen for the 

 central part of a whole line so as to allow 

 a foot of water behind it with no danger 

 of its being breached by wind or defects. 

 At the lowest point the water is often 

 deeper than a foot and at the shallowest 

 points much less, but the general aim is 

 to have it everywhere as near a foot in 

 depth as possible though it by no means 

 follows that that amount of water will be 

 run into it at every irrigation. 



At the bottom these check lines are 

 often as much as eighteen feet in width 

 though twelve to fifteen feet are more 

 common widths for the high parts. They 

 are round upon the top with both sides on 

 such a slope that any kind of machinery 

 can be run over them and cut anything 

 that grows upon them as well as if it were 

 on the level. The alfalfa, grain, or what- 

 ever is in the field is planted upon them 

 the same as in the bottom of the check 

 and, as far as can be seen, grows as well. 



At the lower part of some of the checks 

 is a large gate in the embankment large 

 enough to discharge the water quickly 

 into the next check below. But in most 

 cases the reliance is on cutting with a 

 hoe. It is conceded by the superinten- 

 dents that the gate is much the better 

 and in the long run probably more 

 economical, though more expensive at 

 first. 



These embankments are made with a 



buck scraper or a Fresno scraper and are 

 too large to make with a common plow in 

 any case. With a movable moldboard 

 about ten feet long a common plow may 

 be used to make them if they are not too 

 large. But this makes a heavy drag and 

 for some of the largest checks takes ten 

 horses in heavy soil. In place of the 

 moldboard five or six revolving disks like 

 those on the disk cultivator are set on an 

 axle eight or ten feet long inclined ac- 

 cording to the slope and the whole fitted 

 to a well braced frame of a Stockton 

 Gang Plow. One of these was being 

 tested the day I was there and I saw four 

 horses do the work of eight with it in 

 throwing up a ridge, the whole difference 

 being in the friction of the solid mold- 

 board, the disks turning over instead of 

 resisting. A slip scraper or any kind that 

 bounces will be too slow to do such large 

 work economically. Even the machine 

 above described must have broad wheel- 

 braces rolling against the face and bottom 

 of the cut to relieve the extra friction, or 

 more horse flesh will be needed at once. 

 All this would be too expensive for a 

 small farmer, but for flooding on a large 

 scale it would pay any one to begin check- 

 ing in that way. 



It must be remembered that there is 

 plenty of water here and some things are 

 done that might be inexpedient elsewhere. 

 If you are sure to have water to fill them 

 it is best to have the checks high enough, 

 provided your soil or crops will stand a 

 considerable depth of water. But if you 

 have not the water or have it in heads too 

 small then your high checking is useless ex- 

 pense. The depth of water you may put 

 in a check will depend not only on the 

 soil and the crop, but greatly on the 

 length of time you hold the water in the 

 check. This you should determine in ad- 

 vance by experiments on a small scale if 

 your neighbors' places will not show what 

 it will do. Under the hot sun of the 

 San Joaquin summer, alfalfa will often 

 scald in less than three hours, and if the 

 irrigating water is very warm two hours 

 are none too safe on some spots. Hence 

 the water must be put in and let off 

 quickly. But unless the soil is porous 

 enough, too great a depth of water will 

 puddle it and retard the soaking instead 

 of hastening it, and if porous enough to 

 be wet more quickly by greater depth of 

 water then vou must have a considerable 



