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has been the custom in Argentina. Sixty per cent of the wheat is raised under the renting system. The colonist owns nothing which grim necessity does not compel him to own, and he practices his ruinous methods of farming until the land is completely exhausted. Then he fastens the bullocks and horses to the carts, packed with his many children and his few miserable pots, boxes, beds and implements, and travels until he finds new fields. Mixed farming as known in the United States is little understood or practiced in Argentina, and the farmer is generally either a wheat grower or a maize grower. There is complaint of the methods of farming in all parts of the Republic, however, and a practice of rotating crops is already beginning, by alternating wheat and maize, or by planting the land with alfalfa after three or four years of wheat cropping.' For the best crops of wheat in Egypt, it is sown every fifth year, the rotation being (1) cotton; (2) “birsen’’ (clover) or “full” (beans); (3) wheat; (4) dura (maize); (5) “birsen.” A commercial success has been made of growing wheat and alfalfa together on the dry uplands of North Africa. In Algeria two rows of wheat are sown 4 inches apart. A space of 40 inches is left between the double rows, and in this space the alfalfa is sown. Wheat is sown only every other year. This is of interest, as alfalfa is now the greatest American fodder crop, especially in the arid southwest where durum wheat is being more extensively grown. Experiments with Mixed Crops have been made, chiefly in Canada and North Dakota. Results seem to be in favor of unmixed grain, although wheat and flax have an advantage under certain conditions, as when wheat is apt to lodge, or when there is a superabundance of moisture. In the latter case flax has increased the yield of wheat as much as 6.5 bushels per acre, in addition to giving 1.2 bushels of flax per acre.

IRRIGATION.

Historical.—Irrigation is of prehistoric origin. Water, as was shown in a former chapter, is one of the greatest essentials of all plant growth, and it is also one of the most variable quantities involved. Since the effects of these variations upon vegetation appear quickly, they must have been noticed at an 1 U. S. Dept. Agr., Bu. of Statistics, Bul. 27 (1904), pp. 41-42.

early date, and then it was only another step to supply artificially the needed water. Irrigation was a condition that was indispensable to the settlement of large portions of western America, Australia and South Africa. In meeting these problems during the nineteenth century, the Anglo-Saxon race had its first experience with extensive irrigation. Throughout all the centuries of previous history, the art of irrigation was quite exclusively the possession of Indian, Latin and Mongolian races. It was used extensively by the ancient Chinese, Egyptians, Persians and by the people of India. The Homeric Greeks used small canals in irrigating. In Italy, it was probably as old as the Etruscans. The Romans borrowed the system from the east, and brought it to their country and southern France. The ancient Peruvians also practiced it, and in Spain it dates back to the Iberian life existing under the Roman conquerors.

Modern Irrigation in Foreign Countries.—Irrigation is more or less extensively practiced by all of the great nations of the globe, even in subhumid and humid regions. As a rule, however, the wheat crop is not extensively irrigated, for irrigation is more profitable with other crops. The total area watered runs into millions of acres in most of the European nations. Wheat is frequently irrigated in the Po valley. In Mexico, Argentina and Australia, wheat is irrigated to some extent. Both streams and wells furnish the water. Extensive systems have been planned for Australia, and over 1,000,000 acres could be irrigated in New South Wales alone. Argentina contains large areas which are irreclaimable except by irrigation. The lower valley of the Nile with its delta comprises another great irrigation system, 6,000,000 acres being under cultivation. Egypt is so arid that dry farming is impossible. In 1902 British enterprise completed a dam across the Nile at Assuan. It is built of granite, and is 70 feet high, 23 feet wide at the top, 82 feet wide at the bottom, and 1% miles long. It is the largest irrigation dam in existence, and the reservoir has a storage capacity of over thirty billion cubic feet. The largest increase in irrigated area in recent years has been made in British India, where about 30,000,000 acres have been reclaimed or made secure for cultivation by constructing new supply works. It has been estimated that 80,000,000 acres more can be reclaimed in India. In 1892 over $150,000,000 had been invested, and yielded a large profit, though it was often obtained indirectly. India has the largest reservoir in the world. It covers an area of 21 square miles, and it was constructed for irrigating in Rajputana. It is known as the great tank of Dhebar. Irrigation in the United States.—In America, the town-building Pueblo Indian tribes practiced irrigation perhaps a thousand or more years ago. Their ditches and canals can still be traced in the little valleys near the mesas of southwestern Colorado and adjacent portions of Utah, Arizona and New Mexico, where the cliff dwellings are found, as well as across the border valleys through which are scattered numerous ruins of community dwellings. Their knowledge of engineering is evident, and remarkable. Careful levels have been run over several miles of their canals. The grade was found to be fairly uniform and suited to a canal of such dimensions, as well as in accord with present day knowledge of hydraulics, safe velocities and coefficients of friction. While these well defined remains of ancient irrigation works have long outlived the civilization to which they belonged, there are cases where they have been utilized in modern works. The ditches at Las Cruces, New Mexico, have been used uninterruptedly for over 300 years. Some 70 years before the settlement of Jamestown, the Spaniards irrigated on the Rio Grande. Adventurous mission fathers pushed on to California, carrying the art of irrigation with them. The beginnings of irrigation by English-speaking people in this country were in the Salt Lake valley of Utah, in July, 1847. The Mormon pioneers, driven out from Illinois and Missouri, stopped from necessity on the shores of the Great Salt Lake. They diverted the waters of the little canyon streams upon the present site of Salt Lake City, so that they might raise a crop from the very last of their stock of potatoes and save the band from starvation. At about the same time water for irrigation was drawn from the ditches used for placer mining by the gold miners of California. After the stoppage of hydraulic mining by the passage of anti-débris laws, the ditches were either abandoned or used exclusively for irrigation. Many were enlarged and are still used.

The Extent of Wheat Irrigation in 1899 is shown in the table

below:

Acreage Production o, Irri- - % IrriTotal Irrigated gated Total Irrigated gated Arizona... - 24,377 24, 137 99.0 440,252 436,582 99.2 California 2,683,405 | 161,086 6.0 36,534,407 1,649,455 4.5 Colorado.. 294,949 || 247,644 84.0 5,587,770 5,309,350 95.0 Idaho.... 266,305 82,708 31, 1 5,340 180 1,799,028 33.7 Montana. 92,132 37,710 40.9 1,899,683 843,143 44.4 Nevada.......... 18,537 18,246 98.4 450,812 448,802 99.6 New Mexico .. 37,907 36,638 96.7 603,303 589,185 97.7 Oregon. ... 491,258 16,092 3.3 7,280,443 387,201 5.3 Utah..... ... 189 235 | 108,630 57.4 34 13,470 2,554,248 74.8 Washington...] 1,073,827 14,204 1.3 20,817,753 328,958 1.6 Wyoming....... 19,416 14,753 76.0 348,890 288,180 82.6 Nebraska.......] ............ 14,143 ........ . ................ 185,481 | ........ Total.......... 5,391,348 761,848 14.1 82,716,963 14,634,132 17.7

While considerable wheat is irrigated in some states, practically all that is grown in them, yet the average per cent of irrigated wheat in all the irrigating states is relatively small, only 14 per cent. Excluding California and Washington, where much wheat is raised and little irrigated, this rises to 36.5 per cent; 17.7 per cent of the wheat produced is irrigated, compared to 14.1 per cent of the acreage. On this basis which, however, takes no account of differences in soil, rainfall and climate, the yield in these states would be increased over 25 per cent if all the wheat were irrigated.

The Problems of Irrigation in our country are, and have been, along two general lines: Agricultural and engineering; and legal and social. Of these two lines, the latter has presented the greatest difficulties. Litigation and controversy have been a menace and a source of loss to many communities because no institutions existed for adequately defining, limiting and protecting water rights. The claims of navigation came into conflict with those of irrigation. When streams flowed through more than one state, interstate difficulties arose. Some of these are the basis of a suit by the state of Kansas against the state of Colorado.

Work at the solution of either class of problems has been

immensely handicapped by a most lamentable lack of knowledge 1 12th U. S. Census, 6:825-870,

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of certain essential facts and conditions. Among these are existing water supply, quantity required to grow crops, losses from seepage and evaporation in distribution, character of the control over streams already vested, and measures of administration requisite for an equitable and effective division of water supply among a multitude of users. Such unforeseen results as alkali lands and seepage waters, formerly secondary considerations, are now often the most primary problems. Such irrigation as could easily be accomplished with simple means independent of co-operative institutions has largely been effected. As the work extended, greater problems arose, claims became hopelessly conflicting and united effort under institutional administration became an imperative condition of advantageous development. Water Supply.—There are two sources of water for irrigation: Surface waters, such as streams and lakes, and subterranean waters. The former supply over 90 per cent of the irrigated land. There are three ways of obtaining underground waters: By pumping from wells; by driving tunnels into the sides of hills and mountains; and by using flowing wells. Artesian areas are widely scattered, and individually they are of small size, except in the Dakotas and California. In 1889, 51,896 acres, or 1.4 per cent of the irrigated land, were irrigated from wells. In 14 irrigating states there were 8,097 wells, nearly half of which were used in irrigation. Each well supplied on an average 13 acres, had a depth of 210 feet and discharged 54 gallons per minute; 169,644 acres were irrigated from wells in 1899. Underground waters seem to be present very generally. It is claimed that there is not a farm of 160 acres upon the great plains region without the requisite moisture absolutely needed for from 10 to 30 acres of tillable ground.' The average depth of water applied to crops in 1899 was 4.35 feet, and in 1900, 4.13 feet. Application to Crops.-The two principal methods of irrigation are by flooding and through furrows. The former is generally used in growing grain. There are two methods of flooding, the check system and by wild flooding. By the latter process a level field is completely submerged. When the ground is not level enough for this, the field is divided into compart

1 Hinton, Rept, on Irriga, Cong. serial No. 2899, part I, p. 8.

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