been so satisfactory that much new development is taking place there. These associations, which are organized for the purpose of producing a more uniform product and providing an orderly system of marketing such products, are opening up a new field, with almost unlimited possibilities, and are doing much to create a new interest in irrigation in the upper Arkansas valley.

LOWER ARKANSAS VALLEY.

The water supply of the lower Arkansas valley presages a much greater irrigation development than is evidenced by the present irrigated acreage. This broad valley, widening as it does to almost a level plain, which includes the Rattlesnake and Ninnescah, small tributaries of the Arkansas river, is, for the most part, underlaid with an abundant supply of water. In many respects it is one of the best-watered valleys in the state. The depth to water is not great, varying from ten to twenty feet below the surface. Under these conditions pumping plants are comparatively inexpensive. Distance to market here is short. The seasons are long, and a great variety of crops can be grown. At this time there are about 1,100 acres irrigated in the lower Arkansas valley. The greater part of this is around the cities of Wichita and Hutchinson, where irrigation is practiced principally in connection with truck farms, gardens and orchards. Farms of this character are usually small, and a mere statement of the irrigated acreage does not serve to show the relative importance or value of irrigation. Most of the truck farms practice irrigation. Information regarding the number of pumping plants in the lower Arkansas valley is not available, but there must be a great many, for in Reno county alone the county agent reports there are about 100 pumping plants.

While irrigation has been used more largely in connection with truck gardening, good results have also been obtained with the irrigation of farm crops. As an example of this, in 1920 one farmer reported a yield of forty-five bushels of corn per acre on land which received two irrigations applied in July and August. A portion of the same field receiving no water made only fifteen bushels per acre. Another farmer reports that his corn where it was irrigated three times averaged sixty-five bushels to the acre, while the unirrigated portion of the field made less than fifteen bushels.

The supply of irrigation water in the lower Arkansas valley is obtained almost wholly from wells. Natural conditions in the valley do not, as a rule, favor the development of supply direct from the river. The slope of the valley is small, and generally the land over which the ditches would pass is sandy, both of which conditions are unfavorable for irrigation ditches. Furthermore, while there is usually running water in the river, the supply is invariably lowest when there is the greatest need of irrigation, and the topography of the country affords no opportunity to store surface water for summer use. On the other hand, the coarseness of the sand and gravel which comprises the water-bearing stratum and the closeness of the ground-water plane to the surface are conditions favorable to the construction of irrigation wells, which are not only moderate in cost, but which yield large quantities of water. Considering these conditions, it seems reasonable to believe that in the future there will be a steady increase in irrigation development in this valley.

Wherever ground water is used for irrigation the question of the adequacy

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of the supply invariably rises. A study of the water supply of this valley leaves little room for apprehension. The water-bearing stratum, composed of sand and gravel, is in effect a large storage reservoir. Considering the fact that the river, which naturally flows in the lowest part of the valley, acts as a drain to carry off surplus ground water, it is evident that this reservoir must be full to overflowing whenever there is running water in the river. No one would expect to use water from an ordinary storage reservoir without lowering the water surface, and the mere fact that the ground-water elevation drops during the irrigation season is no cause for alarm. The real test is whether or not the water supply of the valley is sufficient to fill the subterranean reservoir each year during the nonirrigating season. It not only does this, but each year more than a million acre feet of water flows out of this valley on its way to the ocean.

PAWNEE AND WALNUT VALLEYS.

There are approximately 2,700 acres irrigated in the valleys of the Pawnee river and Walnut creek. The larger part of this, 2,300 acres, is along the Pawnee.

While most of the irrigation in this district is in the Pawnee valley, the two are much alike as regards physical features, rainfall, and water supply. Both streams have deep channels eroded down through heavy alluvial soil, and both flow through nearly level valleys, which vary in width from one to three or four miles. The banks of these streams have been built up by overflowing flood water until in many places the immediate bank is higher than the adjacent land. This building up has been so great in some instances that water released at the river bank will flow for a distance of nearly two miles in a direction at right angles to the stream. On almost every quarter section of land through which the stream passes, a point can be found along the bank from which water will flow over practically the entire quarter.

The normal flow of these streams is not indicative of the amount of water they will supply for irrigation. The dry-weather flow of these streams is two or three cubic feet per second, and it is seldom more than ten second feet unless flood water is present. Any extensive irrigation from these streams would be impossible without storage, but the deep channels offer most favorable conditions for the building of dams and the storage of water. A number of such have been built, and their use for storing water and developing a water supply for the valley has been proven highly successful. In a channel which has a slope, as the Pawnee has, of only from one to two feet per mile the building of a dam ten or twelve feet high creates a reservoir several miles long and stores a large volume of water, but the invisible storage due to these reservoirs appears to be even greater than the visible storage. Soon after a dam is built, freshets coming down the channel fill the reservoir full to overflowing and raise the surface of the water in the channel by an amount equal to the height of the dam. This water, some of which gradually seeps out under the adjacent land, gradually raises the water table until within a few years the ground-water elevation in the surrounding valley is as high as the top of the dam. Water for irrigation is pumped from these reservoirs. During the first few days of pumping the surface of the water in the reservoir drops several feet, but a point is soon reached where the inflow of the surrounding ground water so nearly equals the amount pumped out that even a

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continued period of pumping has but little effect in further lowering the water in the channel.

The increasing of the amount of water available for pumping from reservoirs has not been the only beneficial result of the raising of the ground-water elevation. In many places the water table has been raised close enough to the surface to subirrigate growing crops. Several striking examples of this are afforded by alfalfa fields, which in former years often suffered from drought. but which since the raising of the water table are productive throughout the summer, and regularly yield almost as much as surface irrigated fields.

Some of the dams on the Pawnee have been in use for more than ten years. Their value as a means of storing and conserving the surface run-off of these drainages has been so well demonstrated that it is evident, if dams were built at distances of four or five miles apart throughout the courses of these streams, enough water could be stored to irrigate all of the adjacent bottom land.

The typical irrigation plant in the Pawnee valley consists of a dam in the river channel and a pumping plant on the adjacent bank to pump water from the reservoir thus formed. There are a few irrigation plants throughout the valley pumping from wells, but the underground strata are not favorable for extensive irrigation from that source.

Crops grown here are for the most part general farm crops, such as alfalfa, corn, kafir, etc. There is a small acreage of sugar beets raised each year and shipped to the beet sugar factory at Garden City.

SCOTT COUNTY.

Irrigation in Scott county is noteworthy in that there is a well-developed irrigation agriculture remote from any river valley. About 5,000 acres are irrigated with a water supply obtained wholly from wells.

An abundance of water can generally be found almost anywhere in the central or southwestern part of the county at depths ranging from twenty to sixty feet below the surface. In some places this water-bearing formation is of such a nature that single wells have produced a yield as great as 2,000 gallons per minute. Most wells will yield at least enough to supply a quarter section of land.

Pumping plants, for the most part, consist of a single well (usually about twenty-four inches in diameter), a type of centrifugal pump commonly known as a deep-well turbine pump, and either an internal-combustion engine or an electric motor for power. Many of the pumping plants are using an engine for power, but a transmission line extends from Garden City to this district and electric energy is available for all who wish to use it. A notable project here is on the Lough ranch, where Mr. Lough has built a central power station and is operating a number of pumping plants on various parts of his ranch with the electricity generated at this central station. A large oil engine, burning lowgrade fuel oil, is used for power.

The principal crop in this district is alfalfa. Both the soil and the climate are well adapted to this crop. Some of the finest alfalfa fields in the state are here, and remarkable yields have been obtained from them. Yields of from five to seven tons per acre are common, and some as high as nine tons per