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Our Italy, a non-fiction book by Charles Dudley Warner |
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Chapter 9 The Advantages Of Irrigation |
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_ CHAPTER IX THE ADVANTAGES OF IRRIGATION It is necessary to understand this problem of irrigation in order to comprehend Southern California, the exceptional value of its arable land, the certainty and great variety of its products, and the part it is to play in our markets. There are three factors in the expectation of a crop--soil, sunshine, and water. In a region where we can assume the first two to be constant, the only uncertainty is water. Southern California is practically without rain from May to December. Upon this fact rests the immense value of its soil, and the certainty that it can supply the rest of the Union with a great variety of products. This certainty must be purchased by a previous investment of money. Water is everywhere to be had for money, in some localities by surface wells, in others by artesian-wells, in others from such streams as the Los Angeles and the Santa Ana, and from reservoirs secured by dams in the heart of the high mountains. It is possible to compute the cost of any one of the systems of irrigation, to determine whether it will pay by calculating the amount of land it will irrigate. The cost of procuring water varies greatly with the situation, and it is conceivable that money can be lost in such an investment, but I have yet to hear of any irrigation that has not been more or less successful. Farming and fruit-raising are usually games of hazard. Good crops and poor crops depend upon enough rain and not too much at just the right times. A wheat field which has a good start with moderate rain may later wither in a drought, or be ruined by too much water at the time of maturity. And, avoiding all serious reverses from either dryness or wet, every farmer knows that the quality and quantity of the product would be immensely improved if the growing stalks and roots could have water when and only when they need it. The difference would be between, say, twenty and forty bushels of grain or roots to the acre, and that means the difference between profit and loss. There is probably not a crop of any kind grown in the great West that would not be immensely benefited if it could be irrigated once or twice a year; and probably anywhere that water is attainable the cost of irrigation would be abundantly paid in the yield from year to year. Farming in the West with even a little irrigation would not be the game of hazard that it is. And it may further be assumed that there is not a vegetable patch or a fruit orchard East or West that would not yield better quality and more abundantly with irrigation. [Illustration: RAISIN-CURING.] But this is not all. Any farmer who attempts to raise grass and potatoes and strawberries on contiguous fields, subject to the same chance of drought or rainfall, has a vivid sense of his difficulties. The potatoes are spoiled by the water that helps the grass, and the coquettish strawberry will not thrive on the regimen that suits the grosser crops. In California, which by its climate and soil gives a greater variety of products than any other region in the Union, the supply of water is adjusted to the needs of each crop, even on contiguous fields. No two products need the same amount of water, or need it at the same time. The orange needs more than the grape, the alfalfa more than the orange, the peach and apricot less than the orange; the olive, the fig, the almond, the English walnut, demand each a different supply. Depending entirely on irrigation six months of the year, the farmer in Southern California is practically certain of his crop year after year; and if all his plants and trees are in a healthful condition, as they will be if he is not too idle to cultivate as well as irrigate, his yield will be about double what it would be without systematic irrigation. It is this practical control of the water the year round, in a climate where sunshine is the rule, that makes the productiveness of California so large as to be incomprehensible to Eastern people. Even the trees are not dormant more than three or four months in the year. But irrigation, in order to be successful, must be intelligently applied. In unskilful hands it may work more damage than benefit. Mr. Theodore S. Van Dyke, who may always be quoted with confidence, says that the ground should never be flooded; that water must not touch the plant or tree, or come near enough to make the soil bake around it; and that it should be let in in small streams for two or three days, and not in large streams for a few hours. It is of the first importance that the ground shall be stirred as soon as dry enough, the cultivation to be continued, and water never to be substituted for the cultivator to prevent baking. The methods of irrigation in use may be reduced to three. First, the old Mexican way--running a small ditch from tree to tree, without any basin round the tree. Second, the basin system, where a large basin is made round the tree, and filled several times. This should only be used where water is scarce, for it trains the roots like a brush, instead of sending them out laterally into the soil. Third, the Riverside method, which is the best in the world, and produces the largest results with the least water and the least work. It is the closest imitation of the natural process of wetting by gentle rain. "A small flume, eight or ten inches square, of common red-wood is laid along the upper side of a ten-acre tract. At intervals of one to three feet, according to the nature of the ground and the stuff to be irrigated, are bored one-inch holes, with a small wooden button over them to regulate the flow. This flume costs a trifle, is left in position, lasts for years, and is always ready. Into this flume is turned from the ditch an irrigating head of 20, 25, or 30 inches of water, generally about 20 inches. This is divided by the holes and the buttons into streams of from one-sixth to one-tenth of an inch each, making from 120 to 200 small streams. From five to seven furrows are made between two rows of trees, two between rows of grapes, one furrow between rows of corn, potatoes, etc. It may take from fifteen to twenty hours for one of the streams to get across the tract. They are allowed to run from forty-eight to seventy-two hours. The ground is then thoroughly wet in all directions, and three or four feet deep. As soon as the ground is dry enough cultivation is begun, and kept up from six to eight weeks before water is used again." Only when the ground is very sandy is the basin system necessary. Long experiment has taught that this system is by far the best; and, says Mr. Van Dyke, "Those whose ideas are taken from the wasteful systems of flooding or soaking from big ditches have something to learn in Southern California." As to the quantity of water needed in the kind of soil most common in Southern California I will again quote Mr. Van Dyke: "They will tell you at Riverside that they use an inch of water to five acres, and some say an inch to three acres. But this is because they charge to the land all the waste on the main ditch, and because they use thirty per cent. of the water in July and August, when it is the lowest. But this is no test of the duty of water; the amount actually delivered on the land should be taken. What they actually use for ten acres at Riverside, Redlands, etc., is a twenty-inch stream of three days' run five times a year, equal to 300 inches for one day, or one inch steady run for 300 days. As an inch is the equivalent of 365 inches for one day, or one inch for 365 days, 300 inches for one day equals an inch to twelve acres. Many use even less than this, running the water only two or two and a half days at a time. Others use more head; but it rarely exceeds 24 inches for three days and five times a year, which would be 72 multiplied by 5, or 360 inches--a little less than a full inch for a year for ten acres." [Illustration: IRRIGATION BY ARTESIAN-WELL SYSTEM.] [Illustration: IRRIGATION BY PIPE SYSTEM.] I have given room to these details because the Riverside experiment, which results in such large returns of excellent fruit, is worthy of the attention of cultivators everywhere. The constant stirring of the soil, to keep it loose as well as to keep down useless growths, is second in importance only to irrigation. Some years ago, when it was ascertained that tracts of land which had been regarded as only fit for herding cattle and sheep would by good ploughing and constant cultivation produce fair crops without any artificial watering, there spread abroad a notion that irrigation could be dispensed with. There are large areas, dry and cracked on the surface, where the soil is moist three and four feet below the surface in the dry season. By keeping the surface broken and well pulverized the moisture rises sufficiently to insure a crop. Many Western farmers have found out this secret of cultivation, and more will learn in time the good sense of not spreading themselves over too large an area; that forty acres planted and cultivated will give a better return than eighty acres planted and neglected. Crops of various sorts are raised in Southern California by careful cultivation with little or no irrigation, but the idea that cultivation alone will bring sufficiently good production is now practically abandoned, and the almost universal experience is that judicious irrigation always improves the crop in quality and in quantity, and that irrigation and cultivation are both essential to profitable farming or fruit-raising. _ |
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