. Proceedings of the American Society of Agronomy . Fig. 2.—Large field cans used at Nebraska Experiment Station (1910) indetermining rainfall, seepage, evaporation and transpiration. MONTGOMERY: WATER REQUIREMENTS OF CROPS. 27 I vanized iron lid. These cans were used to grow corn plants, andrain was kept out by placing a mass of sculptors clay around theplant. This is adhesive and at the same time pliable enough so thatit does not interfere with the normal growth of the plant. Usually. A .3 Fig. 46,—Diagrammatic vertical section of potometer. a. Galvanized ironsoil can, 3 feet by 16 inches, h
. Proceedings of the American Society of Agronomy . Fig. 2.—Large field cans used at Nebraska Experiment Station (1910) indetermining rainfall, seepage, evaporation and transpiration. MONTGOMERY: WATER REQUIREMENTS OF CROPS. 27 I vanized iron lid. These cans were used to grow corn plants, andrain was kept out by placing a mass of sculptors clay around theplant. This is adhesive and at the same time pliable enough so thatit does not interfere with the normal growth of the plant. Usually. A .3 Fig. 46,—Diagrammatic vertical section of potometer. a. Galvanized ironsoil can, 3 feet by 16 inches, h. Perforated spiral coil for distributing water insoil. c. Six-quart can through which all water is added, d. Lid with openingfor plant, e. Three-inch gravel mulch for preventing water evaporation fromsoil surface. (From Nebr. Exp. Sta.) a collar of oilcloth was used to hold the clay in place. Fig. 47 showsthe method of placing the sculptors clay around the base of theplant. These cans have been used in the open, growing the plants foran entire summer without protection, and weighing9A)efore and afterheavy rains have shown that no water enters the can. Also checkcans have shown that practically no loss by evaporation from thesurface takes place during the summer. Plate IV, Fig. i, shows abattery of 24 of these cans mounted on trucks so that they can beweighed every day. Automatic instruments for recording weatherand climatic conditions—hygrometers, thermometers, windgauges a
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