THE ART OF IRRIGATION. 



155 



crop or orchard. If you reduce the size 

 of the checks to twenty feet you still have 

 over an inch difference. This is all right 

 for orchard work, but checks as small as 

 that are generally a nuisance for alfalfa 

 or most field crops. To bring the larger 

 check right would require only a few 

 inches shaved off the bottom of the upper 

 side and spread over the lower. To do 

 this well is not very expensive and would 

 in most cases be repaid by the better 

 crops and greater ease of handling the 

 run of water. This is best done by large 

 scrapers that carry dirt easily in large 

 quantities, like the Fresno scraper. The 

 man who attempts to economize at this 

 stage of irrigation is very foolish and will 

 ever regret it. Preparation of the ground 

 is two-thirds of the battle, and this is the 

 last case in which to underestimate the 

 enemy. To repair the mistake afterward 

 is generally difficult and in case of or- 

 chards nearly impossible. 



It will also pay to have the flow from 

 the feeding ditch regulated by something 

 better than dirt and the water had better 

 be diverted by something better than a 

 dam of earth or a piece of cloth on two 

 skewers or a bit of board stuck in the 

 ground. Even a sheet iron dam is not 

 the best. It costs little to fix all these 

 things well at the outset and a good gate 

 of lumber with a cut off from the main 

 takes very little material and can be 

 made at home. 



The shape of the checks into which 

 the field is to be cut to hold the water is 

 of no consequence. If permanent they are 

 best made according to the contour of 

 the land; if temporary, square. Where 

 the ground will permit it is common to 

 make them square, but they are made in 

 all sorts of shapes according to the lay 

 of the land, the nature of the crop and 

 the whim of the irrigator. If they can- 

 not well be made rectangular for orchards 

 it is pretty, good proof that the land has 

 not been well prepared and you had better 

 stop right there and go back and prepare 

 it. When so prepared it is more easy for 

 temporary work to make them in squares 

 or "oblong squares," as rectangles are 

 called, than any other form. 



The size of the checks will depend 

 upon the slope of the land, the head of 

 water at your disposal, and the nature of 

 the crop. 



The more nearly level the land the 



larger you may make them. But you 

 must first be sure that the head of water 

 is large enough to fill them quite rapidly 

 and discharge from the upper ones to the 

 lower ones quite rapidly. Otherwise you 

 will have slow and uneven flooding, which 

 should always be avoided. If you should 

 try to flood forty- acre checks with a fifty- 

 inch head of water a cubic foot a second 

 you would find yourself in trouble if 

 you had many to fill. 



The speed with which the water will 

 flow through the checks and pass to the 

 next ones will depend also on what is in 

 them. If there is a stand of alfalfa or 

 grain in them the stalks will retard the 

 flow. You must therefore have a larger 

 head of water. If you have plenty of 

 water, in heads large enough, it is gen- 

 erally best for all field crops to make the 

 checks as large as the slope of the ground 

 will permit. Especially is this the case if 

 they are to be left there permanently and 

 be run over with mowing machines. But 

 care must be taken not to have the ridge 

 too high on the lower side. This may, 

 however, be partially obviated by making 

 them very broad at the base, and this 

 should always be done where they are to 

 be left and run over by machines instead 

 of being broken up every time by cultiva- 

 tion. In all cases they should be so strong 

 that there is little danger of their break- 

 ing. For if one goes the extra rush of 

 water may take the next one, and in care- 

 less work one may see a whole line of 

 temporary checks go one after the other 

 as certainly as a row of bricks. 



LARGE AND SMALL CHECKS IN MEXICO. 



The largest checks I have seen were 

 near Lerdo in the siate of Durango in 

 Mexico. While I have to depend on 

 memory I am certain that I have there 

 seen fields of corn and cotton half a mile 

 square, irrigated in one check almost per- 

 fectly level, and one cornfield in which I 

 hunted ducks several times was fully a 

 mile square. The water stood all over it 

 at nearly uniform depth and the irri- 

 gating head that I saw turned into it was 

 fully five thousand inches or one hundred 

 cubic feet a second. This work was well 

 done and the crops were very fine. I can- 

 not see that smaller ckecks would have 

 been any better. And while a larger yield 

 to the acre could have been had by better 



