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Show Water Economy Program Views Offered Moisture Content Figures Given for Soils (Editor's Note: This is the second article in a scries of three, written writ-ten by William P. Ogdcn. It is the purpose of the series to assist as-sist farmers in the conservation of water during the irrigation season). Last week it was pointed out that watersheds this spring are storing considerably less than average water that can be used by farmers for irrigation purposes. pur-poses. A discussion of ways and means of obtaining CO per cent efficiency follows: This week it is our concern on "When and How Much to Irrigate." Irri-gate." The first irrigation each spring should be a heavy one if the winter win-ter moisture has not been adequate, ade-quate, which is true this year. This deep irrigation serves two purposes: (a) It washes out any salt accumulation in the upper part of the soil, and (b), It provides pro-vides moisture for the plant roots as they grow down. This stored moisture will remain in the soil until the plant uses it. Replaces Moisture Used As the plant grows the irrigator irriga-tor will need to replace only the moisure used by the plant roots. This moisuure is not taken uniformly; uni-formly; it is extracted in approximately approx-imately the following pattern: 40 per cent from the top quarter, 30 per cent from the second, 20 per cent from the third and 10 per cent from the fourth. The irrigator irrigat-or should determine the amount of moisture in the soil before he irrigates. This can be done by estimating es-timating how much Water remains re-mains in the soil by the "feel" or the "ball" test. To make this test, squeeze a handful of soil three or four times just like milking a hard milking cow. The following follow-ing Is a key to b'e used for the different soils and the amounts of water to be applied. For sand to sandy loam: If It will not form a ball, the soil needs from IV to "!4 inches of water per foot. If it forms a weak ball to M Inch per foot. If It forms a ball and leaves a film on the hand U to 0 Inch per foot. Heavier Soils For loam to day: If It will not . form a ball 2 to i inches of water per foot. If it forms a weak ball Vk to 1 Inches per foot. If it forms a durable ball 1 to 'a inch per foot. If it forms a durable dur-able ball and leaves a film on the hand to 0 inch per foot. The Irrigator should know that with "heavy to medium" soils it is safe to use from U to of the stored moisture. With shallow or "light soils" it is safe to use only J,s to of the stored moisture. mois-ture. An Irrigator should check soil during and after irrigation to see if enough water is being applied ap-plied to fill up the dry portion. por-tion. It should be remembered that the extra water applied to the surface soil will drain down for a depth equal to VA to 2 times the depth he finds it wet immediately following (the irrigation. irriga-tion. In other words if the soil is wetted to a depth of two foot below the surface during the Irrigation Ir-rigation the extra water will drain down and wet from three to five feet 21 to 48 hours after the irrigation. With a little experimenting ex-perimenting the Irrigator can determine de-termine every closely the amount needed to' refill the soil to any desired depth. ' ' ' ' The third and final article, to appear on May 5 will Include a discussion of "Uniformity and why it should be obtained" and a linal point "The rate at which water enters the soil." |
