Page:Popular Science Monthly Volume 58.djvu/109

Rh of Agriculture have been particularly helpful in the case of Mexican species.

is the title of an extensive bulletin just issued by the U. S. Department of Agriculture, under the authorship of Prof. Elwood Mead, expert in charge of irrigation investigations, and C. T. Johnston, assistant. It embodies the results of extensive investigations conducted last year with the assistance of a number of collaborators in ten States of the arid region and presents an array of data on the use which is being made of water under different systems of management, such as has never before been collected for the irrigated region of this country. It constitutes a part of the irrigation studies which are being carried on under the U. S. Department of Agriculture.

To many readers the lavish prodigality which has characterized the diversion and application of water for irrigating will come as something of a surprise, when the paramount importance of water in developing the arid country is considered. This has been fostered by the fact that "the laws which govern appropriations of water from streams have, in most cases, no relation to the actual practice of irrigation and therefore fail to secure either the systematic distribution or best use of the available supply." Ditches diverted more water than was used: their owners claimed more than they could divert, while decrees gave appropriators titles to more water than the ditches could carry and many times what the highest floods could supply. Little was known as to the quantity of water needed to irrigate an acre of land, and in the absence of such information the ignorance and greed of the speculative appropriator had its opportunity.

In the investigations reported, farmers whose fields were under observation were instructed to use water as they had hitherto been in the habit of doing. The result of the measurements of the water used showed very forcibly the influence of waste in lowering the 'duty of water' and of care and skill in increasing it. They confirm the conviction long held by students of the subject that the amount of water used in practice bears no definite relation to the requirements of the crop, but is subject to the whim of the individual and the supply of water provided by the contract with the canal company. For instance, the average amounts of water used in different part of New Mexico varied from less than three feet to nearly seven feet. This was independent of the rainfall. In many cases the farmers using the least water got quite as good crops as those who used enormous quantities. On some soils which were not well drained there was a very marked injury from excessive irrigation. In the Boise Valley in Idaho it was found by measurement that fully one-half the water now diverted by canals is wasted under present methods. Apart from the losses from extravagant use of water, there are heavy losses, under present management, from evaporation and seepage from the canals. The average of the measurements made show the loss from this source to be fully thirty per cent. Mr. Mead expresses the conviction that throughout the sections where measurements were made last year it will be possible, through improved methods, to double the average duty of water now obtained, so that the quantity now required for one acre will serve to irrigate two.

The importance of this becomes more strikingly apparent when it is remembered that there is a limit to the amount of land which can be reclaimed with the available water supply, generally estimated at about seventy million acres, or approximately one-fifth of the arid region, and that the thousands of miles of canals and laterals thus far constructed have only reclaimed an area approximately as great as the State of New York.

The results reported in this bulletin