THE ART OF IRRIGATION. 



193 



within the time allowed you to run the 

 water. 



It is best to decide at the outset how 

 much water you will put on a tract in a 

 given time. Two cubic feet a second will 

 cover ten acres to an average depth of 

 three inches in about fifteen hours. On 

 account of mistakes in printing you had 

 better figure over for yourself all such 

 matters, and not rely on printed figures 

 anywhere. But you will rarely need to 

 put on even that amount of water at once. 

 A depth of two inches, which can be put 

 on in about ten hours, is equal to three 

 inches of rain, as it generally comes, and 

 this is enough at a time for almost any- 

 thing, unless the ground is very dry, or it 

 is to be a long time before you can get 

 water again. On a square ten- acre tract 

 there will be about eleven hundred checks 

 of twenty feet square, or thirty-three rows 

 thirty-three checks long. Ten hours' run 

 of two cubic feet a second, giving the 

 equivalent of two inches in depth, would 

 be six hundred minutes or but a trifle over 

 half a minute to a check. But if as small 

 as twenty feet, you do not turn the whole 

 head into one check, but take them in 

 tiers of several. A tier of six would thus 

 give you a little over three minutes to a 

 check. But, then, time is lost in dividing 

 the stream and letting it from one check 

 to the next as soon as one is filled. On 

 the whole it is lively work, but when 

 everything is well arranged, flooding beats 

 the capricious clouds so much that you 

 readily forgive it for keeping you up some- 

 times in the middle of the night while the 

 man who has small streams trickling down 

 small furrows is serenely snoring. 



Checks are generally so arranged that 

 when one is full, or nearly so, the water 

 flows from it to the next one. Sometimes 

 this flow will need help, and where the 

 land is to be broken up again after irrigat- 

 ing they had better be made sometimes so 

 that one will not feed the next one as there 

 is danger of the bank cutting out too soon. 

 How strong or high to make the bank will 

 depend much upon the nature of the soil 

 as well as of the crop. Where the soil is 

 very light it is best to make the ridge so 

 that you have to break it. This is not 

 much of a task ?s you have to be there 

 anyhow, and if the water gets away from 

 you, a dozen men may not stop it before it 

 has done mischief that will cost you much 

 more labor than opening the checks. But 



if the ground is not to be broken up after 

 wetting, as in alfalfa fields, then the lower 

 ridge may sometimes be made so as to feed 

 the next check, and so on to the end of the 

 line, unless you feed each from the ditch 

 direct, which is often done where the 

 checks are large. But it is safer to cut the 

 checks so as to discharge all water quickly. 

 In any case the ridges, if permanent, must 

 be made very strong and very broad at the 

 base. When the roots have taken posses- 

 sion of the top soil a very light stand will 

 prevent cutting of the soil and accidental 

 breaking of the check. All trouble is, 

 however, best avoided by a wooden gate 

 large enough to feed properly from check 

 to check, and it can readily be seen so as 

 not to be in the way of driving machinery 

 over the land. With these properly set, a 

 breach of a well-made check is almost im- 

 possible. 



MAKING THE CHECKS. 



A common way of making the checks is 

 by throwing up ridges with a plow or 

 scraper. On some soils two plow furrows 

 running in opposite directions, so as to 

 throw the sod to the center, are enough 

 for almost all temporary checks. This, of 

 course, means very level ground, and it 

 may be so nearly level that it is not neces- 

 sary to throw the two furrows together. 

 And some ground is so near a perfect level 

 that one furrow will often do. Stubble is 

 often wet in this way to prepare it for 

 plowing, and by making the furrows only 

 a few feet apart, land quite sloping may be 

 well wet. This is a good enough way to 

 prepare some ground for plowing. But in 

 all cases where the ground is already so 

 loose that a scraper may be used, it is best 

 to throw up a good ridge, for with that a 

 larger amount of water may be put into 

 the ground with much less danger of un- 

 even wetting. 



What is probably the best scraper for 

 this purpose can be made by any one. It 

 is called a "ridger" and is nothing but a 

 sled with solid board runners. These 

 converge at one end and diverge at the 

 other according to the ease with which the 

 soil will scrape and the size of the ridge 

 you are to make. One five 'feet long with 

 the opening between the runners a foot or 

 so wide at one end and three at the other 

 will make checks strong enough on most 

 soils to hold water five inches deep if the 

 soil is in good cultivation to scrape. But 

 the size of the ridger will vary with soils 



