VOL. IX.

No. 4.

ALL systems of making water soak side

ways from ditches are practically the same, no matter by what name called or how many distinctions may be multiplied from different ways of running the water. Filling up the soil with water from below by seepage from large ditches around the tract differs somewhat from this, but hardly enough to justify calling it a new system. Sometimes it is done unintentionally and on a very large scale, as in parts of the great San Joaquin valley in California, where the steady seepage for several years from large ditches and waste water has raised the level of underground water, over tens of thousands of acres, from sixty or seventy feet to six or seven or less. Sometimes it is unintentionally done on a small scale by the use of too much water on land having hardpan, clay or other impervious material beneath. On all land not well drained it is liable to happen from very ordinary waste after the land has been irrigated several years. And sometimes it is done intentionally where the conditions. will allow it. And where the soil is very "leachy" (lets water through too fast) it máy be advisable to do it as the cheapest method, and in some rare cases the only method. Its simplicity commends it in many cases where other methods are far better, and it is the favorite of many a lazy man who has plenty of water, because there is nothing to do but let it run. Sometimes the ditches are made around the tract, sometimes across it, sometimes both; often they

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FLOODING.

are large and often small, but it is all the same, and is generally possible only on land that is quite sandy.

At first glance it seems fine to dispense with work and cultivation in this way, and have the roots go down out of the way of evaporation. Being a kind of subirrigation, it has all the attractions of that system with apparently none of the disadvantages of underground pipes.

Time, however, shows that many things are injured by having the roots in standing water, while some are killed. It is doubtful if anything does as well that way as under surface irrigation on land well drained. It certainly does not if the water becomes stagnant and heavily impregnated with salts of iron, making it "sour," as it is often called. And if the water is clear and changing, with a steady underground flow, it is doubtful if anything does as well in it. While alfalfa will grow on such ground, and often give large yields, it has been proved over and over again that alfalfa, on well drained open soil with surface irrigation, is still better. The same is true of the pear, which will often do well on ground too wet for other deciduous trees, but with plenty of water does still better on well drained benches. With the orange and lemon, and most of the deciduous fruits, there is no longer room for question. Grapes of some kinds will bear heavily on wet land, but you can see the difference on higher soil, while the finest corn I ever saw was

on land twenty feet from water and heavily irrigated with warm water on the top. Eight acres averaged 115 bushels to the acre, and most of it was over fourteen feet high. I have seen very fine corn in the same region and on the same kind of soil, low along the river where the water was but a foot from the top, but it would not run over ninety bushels. On the whole, it is pretty safe to say, do not irrigate in this way for anything unless there is some special economy in it, and then plant only such things as you are sure will stand it.

Where the head of water is great and the feeding flume large enough, furrow irrigation may become practical flooding, as in the picture given in Chapter X of bad furrow irrigation. If you had 180 streams of one miner's inch each, and should run them, for twenty-four hours on ten acres, this would be one half of 360 twenty-four-hour inches, or about half the whole allowance for the year under many of the best water rights in Southern California. This would equal about nine inches in depth, or three-quarters of an acre foot. Nothing but very coarse sand could take such an amount of water as that, even if distributed over the twenty-four hours evenly in steady fine rain. The folly of trying to put it on from a ditch must be apparent. Yet that was about what the irrigator was trying to do in the picture of bad furrow work. It leaches out fertilizers, cuts the soil and is in every way bad. When the soil is so coarse as to require such large streams you are approaching the point where it is best to flood. Nothing but sandy or gravelly land will need streams of an inch apiece, and nothing but land nearly level will stand them. You have, therefore, the conditions for flooding, and had better do it directly than indirectly. You can then save your fertilizers, avoid cutting and do better work.

Where you can get a large head of water for only a short run you are generally compelled to flood no matter how well small streams might run upon the soil. This is liable to be the case at times on many ditches depending on the flow of a stream and not supplemented by reservoirs. If the amount of water used is based on the average of the summer flow, as it should be instead of on the minimum, on which no one can figure and which should not be established as the limit of the capabilities of any country,

there will be times when a run of large heads for a very short time may be the only way of accommodating all consumers. This is liable to happen at the driest and hottest part of the season when vegetation is demanding the most water to evaporate and will suffer the most if it does not have it. And sometimes it wants it furnished very quickly, too. In such case you may have to take a hundred inches of water for five acres and handle it all in two hours or so. And you may have to be on hand at three o'clock in the morning to take your turn, and every minute you lose is so much gone, for at the precise minute it is cut off. Such occasions are short, but you should figure on them as possibilities. You should find out such matters before buying or planting, and especially before deciding what system to adopt. Sometimes it is easy to change from flooding to furrows and vice versa. But sometimes it is not. It will depend very much on how you have prepared the ground.

PREPARATION FOR FLOODING.

If land is to be flooded even more care should be taken in preparing it than if it is to be watered from furrows. The depth of water in all the checks should be as nearly the same as is consistent with reasonable economy in grading. And it will not do to economize too much in this. In many cases it would ultimately pay to terrace the land somewhat in very broad steps, taking care to leave no jump off places, but smoothing it down so that machines can run over it. If the checks are not level then the water stands deeper in one place than in another. For best results the water should be rushed over the land in as thin sheets as possible, and never allowed to stand longer than requisite for enough soaking. Otherwise uneven wetting results and the lower part is puddled too much, both bad whether cultivation is to follow watering or whether the piece is in something permanent, like alfalfa.

If your land has a slope of twenty-five feet to the mile, which looks almost level on a large plain, checks one hundred feet wide would have the water in the lower side about six inches deeper than on the upper side. If you increase the depth so as to give enough to the upper side you injure the lower, for the six inches it already has are too much for almost any

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 orchards 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 cannot 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

But

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 generally 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. 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 cultivation. In all cases they should be so strong that there is little danger of their breaking. For if one goes the extra rush of water may take the next one, and in careless 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 state 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 perfectly 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 irrigating 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 cannot see that smaller ckecks would have been any better. And while a larger yield to the acre could have been had by better

plowing and cultivation, it is not easy to say that the difference would have paid.

There is little land anywhere that will justify such large checks. This was the most level land I have ever seen, and was probably once the bed of a lake fed by the River Nazas. The water was practically of uniform depth throughout and took over two days to spread thoroughly over it. There were dry places all through it, but so very low and small that they amounted to nothing. They came, no doubt, from uneven plowing, but the water soaked through them fast enough.

On the other hand, the smallest checks I have ever seen used for field crops were in Mexico on a large hacienda near Jimenez. Several thousand acres were planted in wheat, and the whole was in checks about ten feet square. I was over it several times in January and the stand of wheat was very good and it no doubt made a fair crop. The land was black adobe. The checks were made with the common wooden plow of the country-a bit of log six or eight inches in diameter sharpened at the end. They had in places been patched up with a hoe, but the whole work was quite well done. It could pay only with very cheap labor like the peon labor of Mexico. The checks were undoubtedly so small on account of the slope, which did not appear great on account of big mountains in front, but which must have been considerable to require so much labor.

METHODS OF THE CHINESE.

For lettuce, radishes and other vegetables to be grown very early, the Chinese market gardeners often use checks even smaller than ten feet, and even on level ground. They seem unable to tell the reason, but it no doubt is because they can in that way run a thin sheet of water over the whole, get it in the ground more evenly and in less time per square foot than could be done with larger checks. In this way there is no such chilling of the

ground or puddling in places as if more water were turned into larger checks. By taking care in this way they raise good vegetables in fair quantity without any cultivation, even yery tender ones suffering little if any.

But when it comes to later crops and things to be grown on a larger scale, the Chinaman finds this small checking too slow. He then makes them of many sizes and shapes. For tough stuff like cabbage he will sometimes make them half or even the whole length of the field, and from twenty to a hundred feet wide. He prefers furrows for almost everything where they can be used, but when they will not work to advantage he does not hesitate to flood. But he tries always to rush the thinnest sheet over the ground in the shortest time, unless the nature of the crop makes it unprofitable to spend too much work on it. He is a good irrigator and no one can afford to ignore his work. It is worth studying for the principles involved, and cheap as his labor is, he is still a close figurer in economizing work.

For alfalfa and other field crops where the land is flat enough and the head of water large enough, forty acres make about as large a check as is generally consistent with economy. In the San Joaquin valley of California, probably the greatest alfalfa region in the world, many are larger than that. Many are also smaller, and it is difficult to see any advantage for ordinary farms in having them over ten acres for anything. While it is well to imitate the methods of prosperous settlements, you must still remember that the secret of success in flooding is to get the water in the ground as rapidly as possible and in as even sheets as possible, avoiding all puddling and scalding, which will result if the water is allowed to stand anywhere too long. Other things being equal the smaller the checks the more easy it I will be to do this.

(To be Continued.)