174 



THE IRRIGATION AGE. 



Best Methods of Irrigating. 



Corrugation Method Preferable to Flooding Amount of Water Controls Character 

 of Root GrowthSoil Should Have Plenty of Moisture at Planting Time. 



By A. McPherson, Idaho. 



Mr. McPherson's lecture on irrigation at the farm- 

 ers' institute at Aberdeen, Idaho, was probably the most 

 helpful of the series, inasmuch as it dealt with the fun- 

 damental principles of irrigation. Irrigation, he said, 

 meant the supplying of water in the right amount at 

 the right time. Water is the one element necessary to 

 plant life which is under the control of man, and the 

 good irrigator can control plant growth with as much 

 certainty, almost, as he can the shape of his buildings. 

 The man who does not understand something of 

 plant growth can never become a good irrigator. Water 

 must be applied in a scientific and rational manner, 

 because it is the lever which controls production. Moist- 

 ure, air, heat and plant food are the elements which 

 control plant growth. Water is the vehicle which car- 

 ries food to the plant. Descending into the soil it dis- 

 solves the chemical food elements, and rising by capil- 

 lary attraction, carries that food to the plants. Bear 

 in mind that it is not the water going into the soil, but 

 that coming up which feeds the plant. . 



Plants should grow continuously from the time 

 the seed sprouts until they mature. If they are sup- 

 plied with moisture in the right quantity and in the 

 right way, they will do so. If the soil is saturated with 

 water to such an extent as to expel the air, the growth 

 of the plant is checked. This is one reason why irri- 

 gation by the corrugation method, or in small trenches. 

 is preferable to flooding. Bear in mind never to keep 

 the soil saturated. Water in the soil forms in thin 

 layers around the soil particles. If these particles are 

 cubes, with inch surfaces, there would be a film of water 

 on all sides of the cubes. If this cube were pulverized, 

 or changed to a powder, there would be as many films 

 as there are soil particles. Therefore a fine soil will 

 hold more moisture than a coarse soil, because there are 

 more interstices to be filled. Ten per cent of moisture 

 in these interstices and the balance air is about the 

 ideal proportion. 



Thus good cultivation, in having the soil well pul- 

 verized, is an aid to good irrigation. 



The roots of a plant are always larger than its top. 

 That is, the roots extend further into the ground than 

 its top does above it. The roots may run along near the 

 surface or may be made to penetrate deep into the soil. 

 If the soil is kept wet when the plants begin to grow, 

 their roots will keep near the surface. But if moisture 

 is withheld, the plants will hunt for it, the same as an 

 animal, and send their roots deep after it. The deeper 

 the roots go the larger the feeding ground of the plant, 

 and the thriftier the plant will be. 



Thus, by the application of water, the irrigator 

 may benefit or injure plant growth. A plant with roots 

 near the surface will require frequent irrigation. One 

 deep-rooted requires much less water. Thus by start- 

 ing right the irrigator may either make or save himself 

 work. 



As between the corrugating or flooding methods, 

 he preferred the former, for two reasons: a better and 

 quicker distribution of water, and less liability of check- 

 ing plant growth. In the corrugation or furrow method, 



furrows three or four inches deep, and two feet apart, 

 should be made in the field immediately after planting, 

 before the seeds sprout. These furrows readily conduct 

 the water, carrying it across a field in much less time 

 than when flooding is resorted to, and distribute the 

 water more evenly. The rise of an inch or two in a 

 few square rods of ground is scarcely noticeable. Yet 

 water cannot be forced upon such ground without im- 

 pounding it by dams and making the low places too wet 

 while the high ones are getting moisture enough to make 

 the plants grow. Where a furrow four inches deep is 

 made through such high places the water flows without 

 interruption, and soaks in about twelve hours from one 

 corrugation to another, leaving the surface generally 

 dry, and supplying the water to the roots where it is 

 needed. 



The best results are obtained, in permanent ditches, 

 by placing spouts made by nailing lath together, in the 

 sides of the ditches to take the water from the ditch to 

 the corrugations. One spout will supply two corruga- 

 tions. These spouts should be placed in the side of the 

 ditch, about one inch or so below the water level when 

 the gates are closed. For instance, say the fall is two 

 feet to the half mile, and your ditch eighteen inches 

 deep. If a gate were put in at the lower end of the 

 ditch it would back water up only three-fourths along 

 or across the field. But begin about two hundred yards 

 from the upper end of the ditch, and put in a gate that 

 can be raised and lowered, but not quite so high as the 

 banks of the ditch, so that water will run over the head- 

 gate instead of the embankments. By closing this gate, 

 it will back the water up, and leave a water line, show- 

 ing where to place the spouts. Further down, put in 

 another gate, or as many as are required. The greater 

 the fall, the more gates required. When you want 

 water, close the gates and raise the water above the 

 spouts. When through, raise the gates, the water level 

 falls, and the water passes harmlessly away. When 

 ditches are constructed this way it is a pleasure to irri- 

 gate and requires little time. 



In preparing your ground for irrigation (for per- 

 manent fields) do it right. Made right once, it is al- 

 ways right. If no more than ten acres can be prepared 

 in one year, do it right, because it will pay in the long 

 run. Have your land level. By level is meant free 

 from knolls, with a slope. Water cannot be made to 

 run up hill. If the slope is too great, run the corru- 

 gations around the slope in steep places, or parallel 

 with the dtich as near as may be necessary, instead of 

 from it. A fall of an inch to a rod makes a good flow 

 for corrugations. When the land is quite level, do not 

 flow the water too far, but catch up in other ditches 

 and begin quite anew, because the upper part of the 

 field will become too wet before the lower part has 

 water enough. If the land has a good fall it will run 

 a quarter of a mile without injury. If it is very level 

 it is advisable to have cross, or catch ditches, every 400 

 or 500 fet. To illustrate, suppose your land is quite 

 level and 'has a gradual fall to the southeast, with the 

 water coming upon the land at the highest point, the 



