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Show IRRIGATION 1 -- isi THE ART OF IRRIGATION. Ilhviug your ground level enough and levees strong you turn on the water and are quickly plunged into despair by the fact that it is not spreading fast enough to cover the check in half a day. You have merely mere-ly made the natural mistake of most beginner in having the head of water too small, or, what is the same thing, having the check to large for it. Some turn in too large a head, wash out the entrance gate with the eddy, cut a big hoh in the ground and wash the silt over the ground to make it bake worse, break a lever which goes so quickly that it takes the next check perhaps or' a whole line of them before be-fore the water can be -shut off. Too small -a head is just as ibad in loss of time and waste of water also, for if it takes loo long to cover the part of the check that first receives it more water soaks in there than it needs, while the rest docs not get enough. This slow feeding is 'a constant source of annoyance and loss and to avoid it properly you must understand the measurement of water, a subject puzzling puz-zling to some, but simple enough to one who will take a little time to study it. The standard measure in the United States is a cubic foot a. second, or "second foot," as it is more commonly called If you had an aqueduct one foot deep and one foot wide inside with the water moving at in averages velocity of one foot a second this would give you a second foot. 11 "c the surface velocity is not the average velocity, because of the friction. For the smoothest flume the surface velocity ve-locity in the center should be 25 to 35 Ier cent more than one foot second and for rough ones often twice that. By dropping a handful of ant meal into a flume carrying water you wilt sec the whole thing s sonic J of the particles float and others sink slowly to the bottom; Even .a flume of glass will show 'ddics all through it in this way and every one of them in.eau spmc loss of velocity. . But you don't have to be accurnte about this. You need only remember that a second foot is seven and ft hair gallons a second, or a kerosene can, once and a half full, and that it will J equal ar inch of rain an hour on one acre or two feet a day," '"" To measure this accurately enough I when running requires a weir which 1 I 1 vou will find so well described in : I . I other books on irrigation or hydrau- J I lies that I shall pass it by for want of i space, it being only one of the instru- J ments of irrigation and one that you 1 may not have to use at all.. This weir 1 is essential for large quantities of water, but for small ones is generally j . a nuisance. The miners in early days t 1 k of California adopted a pressure , measurement which for small quan- ' tities is accurate enough and is often used to measure as high as two sec-ond sec-ond feet or over. Thus, if a hole an inch square be made in the side of a 1 box and the water inside be kept at j a level of four inches above the ecu- 41 tcr of 'the hole be kept at a level of hole the discharge will be, practically one-fiftieth of a second foot. This ., , will be about' nine gallons a minute, ', about thirteen thousand Jm twenty- 1 , four hours, will just 'fill .a. 12-foot cube ( in twenty-four hours which makes , 1,728 cubic feet a day. This is the common measurement for small quantities in' California, Arizona and some other states, but in others it is under a pressure of six inches or even seven In all cases it is called the miner's inch. But you know not what it is until tljc pressure is given. It is used with a hole one, two or three indie? high, and mnny inches long with the .pressure kept j even on the center, the clischargc bo- . ing regulated by a slide running in 4 from one end. The difference in prcs- I surcs makes great confusion and this I is not the best measurement, though j you should know what " it is. The jl four-inch pressure has the: '.advantage m of being one about fiftieth of a sec- W ond foot, which equals half an inch jfl (rain measure), in twentyj-faur hours S on one acre. fl The acre foot is i more-satisfactory M expression for the quality of water M used in irrigation, being the amount jfi necessary to cover on .acre a foot j deep. An acre inch is also used the -' sme way though a rain inch or a rain ;jj foot is simpler as every one under- ,jfm stands rain measure. For this reason vV I shall use the rain inch in this book M wherever possible. $F Now if you 'could just lay down a 'blanket of water an inch thick on an acre perfectly flat with levees wround ' it to keep it from running of! before it could soak in you might be happy, for a while at least. But this is exactly ex-actly what you cannot do. If the soil is as porous as it should be for good results it will be quite sure to cut badly if you rush in water enough to cover a check in a few minutes. And even then you are likely to get into the ground an inch and a quarter or more on the side near point of delivery de-livery o three-fourths of an inch (rain measure, remember), or less on the side opposite place of delivery. You may think you can fix this by having the bottom of the check on Oi islopc with water delivered at the highest edge so that it will run over quickly. The theory of the novice is that while it is running over the high ground it will be soaking in whiLc the water that collects on the lower ground will compensate in the time I it stands and soaks in for the greater t length of time that it was running over and soaking into the higher j ground. This would be viery fine if I the soil were all of uniform texture, MHMHII perfectly graded and perfectly bare, the first two being conditions you arc not apt to get. But when it is covered cov-ered with vegetation you can be certain cer-tain that uneven wetting will result. And this cannot be prevented by any number of delivery pates at the up- per side. Good gates -cost money and labor and one to a check is- generally all you can afford', for it is enough if other conditions arc right. And the first of these conditions is ahead of , water proportionate to the size of the ! check. Mark now the distinction (between the quantity of water you have, mcas- i urcd as a. running stream, and the amount you can have available for . use at a given time, for there is nothing noth-ing more important. Suppose your ; water right is a second foot to 160 acres, a usual allowance for common (Continued on page 10.) I riRRI CATION J THE ART OF 'IRRIGATION. I 1 I (Continued from PIe 3-) H farming in many sections. This is on H nlie assumption of a continuous flow H , of that amount, and if from a private H jartcsiarv well, small running stream or H mumping plant, it will probably be H . a110)1 a ow But a continuous flow b "js the last thing you want for that B mmpunt of land, yiiat you need will. m Jbc (the equivalent of such a continual continu-al ous. flow instead, of the actual flow. 1 second foot running all the time t" would be such ai slow feed into checks F reasonable size that lralf or two-' two-' h" cnirds of the water might be wasted M by (too much soaking into the upper m pari of;1he checks before reaching the H lower parts1. It would also take much iiB j2 B more time 'and' labor to watch it and M change from check to check than if m vpuj hadi say, ten times that amount H runhing for t one-tenth of the time. M In fact, for some results a second H foot vcry day for 365 days may not M be as good' as 365 second !fect for: 01.1c ' H day.1 H mThcrcfore, you heed sonic' kind of H tw reservoir to accumulate the flow B fiyej ten, twenty -or , forty days of H monc, according to your climate, soil H I andfcrop and give you the whole ac- H i cumulation in a much shorter time. H M private reservoir to do this would B cost too much in most cases, but H ewery well managed ditch is practical- H lVi such a reservoir. Instead of caqh H consumer taking water continuously H . he takes a larger amount at intervals H i H oh many days. This, enables every H consumer to get the amount he wants H With, almost a certainty, provided he iH H putsjin'his order to. the ditch-tender H on secretary long enough ahead to H allow him to arrange matters so that H he docs not interfere with other con- H sumcrs. The amount thus taken is H. callcil "an irrigiating head," while the H amount for the year which it -equals B J infeontinuous flow is called the "wat- B i erlright." Using a big "head" once In B a jvHile, instead of a, continuous flow, H tv$kts lively work for a short time H a4tPUt Uie water into the soil with H the Bawdiest tamount of waste from H oo&kkmed soaking after it lvas enough. H Tfee content flow keeps work going H a fee &mc to irrigate a much smaller V sk MgeUy, the larger the H t4 Hke mace -wk it will do pro- H rAH U 4& act cvl owr "gatei? or levees or wash too much mud and silt where it is not wanted or ; interfere with proper clearance of the checks after enough water has soaked in. Tliisciult cannot always bJe rca.ch . cd by making the checks small enough. You may find every gate ne'edsra cross gate in the ditch which will increase the cost. You may have to lVivc haying machinery over the levees and must not have them too numerous. There is a temptation to make them flimsy to save the in-tencased in-tencased cost of so many more and if well made there is so much more room for gophers and siu.h things to climb up in to escape drowning. On the other hand, the larger the checks the more difficult it is to adapt the -size of the head so as 'to prevent waste of water from too much soaking soak-ing on the entrance side more dangerous dan-gerous from wa.vcs washing out a levee when full of water, more damage dam-age if it docs break, and more difficulty difficul-ty in having quick clearance of the water wljcrc soil or climate makes it ncccssiary. Near Lcrdo, Mexico, in 1884, I saw a check of abotit one thousand acres, all in corn. It was an old lake bed apparently dead level and took about all the flow of the Nosqs River over a day to fill it. The corn was very fine, but I think it was due to excessive exces-sive richness of the soil rather than good irrigation. I could sec no reason rea-son for making so large a check except ex-cept the saving of labor in the first instance to' pay for it later on several times over in water and work. Later ' on I saw near Jimenez, Mexico, on about the same soil and with same climate some five thousand acre's in checks. about twenty feet square. It was all in wheat about three inches . high and looking as well as wintci wheat ever looks. The head available avail-able was smiall and probably was not uscdl over ' twice during the Whole winter und spring. Between these two extremes a great varidy of sizes from 200 acres down to half or quarter or an acre ore in use in California and other states, but the tendency is toward to-ward smaller ones. The large ones are of all shapes according ac-cording to the contour of the land for it would not pay to grade tlhcm flat or make them square. Perfect levels are run for the lover levee which makes many checks vary, fm harp crescent to a half moon. In some the water will be a foot deep at the lovcr side and aboutan inch or so alt. lie upper side. Few have the water less than si-'c inches deep at the lower levee. Tt is plain that if the cropis good cnbugh oii'lhc upper part where the water is shallow that the lower half had at least twice as much as wjis needed. This enormous waste (s jal-lowcd jal-lowcd because water is so plenty that it is cheaper than labor and so io grading or very little is done. Butfl have seen alfalfa fields where,' the scalding of the crop at the lower, side on oi hot day caused iby the water i T standing too loiig would offset the f B cost of grading in three" or four years beside swing half the water. : .,jr In such cases the ditches also, fol- low the contour of the land. This ; means ditches cheaper by the foo. . "S but also longer, with more loss of water 11 om seepage and morel expense ex-pense of cleaning. But it also means much less expense at first and, as there is so much expense in irrigation that you cajinot avoid, it is justifiable in most cases. I wish only to show that they are not good models except in the line of economy at the outset. It is a question of finance rather than of irrigation. If you have your own teams and feed and can do-your own work it will probably pay you to make siriall checks and grade them perfectly flat on the botton and also square and make the ditches straight and parallel. If knolls of any size arc too high save them dry for buildings, build-ings, corrals, haystacks, etc., but force the water to run as) you want it' in- ft stead of laying the land to accomino-datc accomino-datc the water. This again is a question ques-tion of the value of your crop, but be careful how you decide that it is.jtoo expensive. I find one-third of an acre about the best size for checks because water is more valuable j for new land than to throw away on :the old. I ma.ke them flat, although jthe slope of the land is only three inches in ai hundred feet. As these chqeks are about one hundred and twenty feet square the difference between ,the upper and lo.wcr side is less than four inches. But that wastes too much water on the lower srd'c and where it is necessary to leach out alkali there is not prcs-sure enough on the upper side to get quick and uniform results. I make "them level even for-alfalfa1 aiuj 1 T cun get it in early enough tn the, fall the next year's crop, with oats for hay: the , first winter, repays the entire cbst df the finest work. After that there is a constant saving of considcra'bic latbr in waiting' and 1 watching tjtc 'filling besides; the sa- 1 ing of one-half of the water. I the 1 head 'should be short in quantity or 1 time of 'running you can cover the I whole flat, where it would leave a big' dry strip on the upper side and one below it only half wet if it were not level, T.-S. Van Dyke in Irrigation Irriga-tion Ags. 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