ARTESIAN WATER FOR IRRIGATION.

New Zealand Mail, Issue 1291, 26 November 1896, Page 4

ARTESIAN WATER FOR IRRIGATION.

Writing in the Forum, Mr E. V. Smalley, the United States representative of the Times, says:—ln South Dakota a remarkable movement is in progress for irrigation by artesian wells. Nearly the whole of this State and of its northern neighbour is underlain with the water-bearing formation known to geologists as the Dakota sandstones, which forms a vast artesian basin, fed by the rivers that flow over and the rains that fall upon its western rim in the foothills of the Rocky Mountains, the big Horn Mountains

and the Black Hills. This formation has been fairly accurately traced already by Government explorations and by the sinking of artesian .veils here and there to afford a water supply for towns and the recent borings for irrigation wells confirm the earlier theories of the geologists. The water-bearing stratum is found at Yankton, in the extreme southern part of South Dakota, at a depth of 600fc. It is about 1000 ft below the surface in the central region of the State, and at Jamestown, in North Dakota, the well that furnishes fire protection and local water supply isdown about 1500 ft. The irrigation movement is at present confined to the lower James River Valley and the countries lying along the eastern sile of the Missouri River, in South Dakota. A single statement will show how important this movement has become; There are now more than 1100 wells completed or in process of boring. In many cases townships have banded themselves to carry on this work; in others, farmers have combined to buy machinery and sink wells for themselves. Financial projects are now being formulated by which wells will be sunk by stock companies and sold to farmers on annual payments, with security in the form of mortgages on the land to be watered. The subsoil in this artesian basin holds water so well that experi-

ence has shown that is not necessary to irrigate a field every year. Once thoroughly soaked the land will produce good crops for two and perhaps three years without further irrigation. This is a very great, advantage, for it doubles and trebles the irrigating value of a given amount of water. Of course the natural rainfall helps out the crops and lessens the duty of the irrigation system. Thus good crops can be raised in this region with perhaps one-third or even less water than must be applied in more arid regions, such as Colorado, Utah and Idaho, where little aid can be expected from rains and where the subsoil along the river margins is usually gravelly, The results of irrigation in South Dakota have been very favourable. Irrigated fields produced last year 35 bushels of wheat to the acre, while adjoining fields, which depended on rainfall, produced only twelve. It will be seen that with this enormous gain in the yield of crops, a well costing from two to three thousand dollars and watering an entire section of 610 acres will pay for itself in a single year. It must not be concluded, however, that all of the sub-arid belt which lies above this water-bearing sandstone is destined to become a country of contiguous irrigated farms. There must be a limit to the number of wells that can be sunk in a sin«le township without diminishing the flow. That limit has not been ascertained. The subterranean waters do not constitute a great reservoir. They percolate through the porous sandstone under hydrostatic pressure derived from the elevated position of their places of original absorption. Every well must relieve the pressure on a considerable surrounding area. If it should turn out, however, that there is water enough under ground to regularly irrigate every other year 80 acres in each section of 640 acres in this entire artesian basin, the region in question will soon- become one of the most prosperous in the United States. The remaining land will be utilised for pasture, and the forage crops and corn produced upon the irrigated fields will enable the farmers to raise fat cattle and hogs to great advantage.