98 



"The general appearance, and more particularly the color of the plant, 

 are the best guides, perhaps, as to when water is needed. When healthy 

 and vigorous, alfalfa is of a light-green color; but when the supply of 

 moisture is insufficient the leaves take on a darker and duller shade of green 

 and begin to droop, and unless water is provided both stems and leaves 

 wither and die. Another test is to remove a handful of soil 6 inches or so 

 beneath the surface and compress it in the hand. If it retains its ball-like 

 shape after the pressure has been removed, and shows the imprints of the 

 fingers, the soil is sufficiently moist, but if it faHs apart readily it is too 

 dry. In connection with such tests it is well to bear in mind that they are 

 more or less influenced by both soil and climate. It is therefore necessary 

 to observe the growth of the plant closely on all new alfalfa fields to 

 determine if possible how f?r such tests may be relied upon, the chief 

 object being to maintain at all times as nearly as practicable the proper 

 amount of moisture in the soil surrounding the roots of the plants to 

 prevent a checking of their growth. 



"Alfalfa commonly receives careless treatment at the hands of western 

 irrigators. When water is available and is not needed for other crops it 

 is usually turned on the alfalfa fields or meadows whether these need it 

 or not. There is no question that yields of alfalfa might be considerably 

 increased if more care was used in finding out when to apply water. In 

 each kind of soil and under any given set of climatic conditions there is a 

 certain percentage of soil moisture which will give best results. Under the 

 present unskillful practice it is impossible to maintain uniform soil- 

 moisture conditions for any length of time. The soil is apt to receive too 

 much or too little water, or else it is deluged with cold water at a time 

 when it needs only heat onl air. The number of irrigations required de- 

 pends upon the depth and nature of the eoil, the depth to ground water, 

 the number of cuttings, and the rainfall, temperature, and wind movement. 

 Other things being equal, more frequent waterings are required in the 

 warm sections of the South than in the cooler portions of the North. The 

 number of irrigations per year for alfalfa ranges from 4 in Montana and 

 Wyoming to as many as 12 in parts of California and Arizona. In localities 

 where water is scarce during part of the season the number of waterings 

 as well as the amount used each time depends on the available supply. It 

 is a common practice to apply frequent and heavy irrigations in spring 

 when water is abundant and to water less often and more sparingly when 

 the supply is low." 



5. Winter Irrigation of Alfalfa. 



"When water is applied either to bare soil or to crops outside of the 

 regular irrigation season it is termed winter irrigation. The practice 

 thus far has been confined largely to the warmer parts of the arid region. 

 It has become well established in Arizona and California and is being quite 

 rapidly extended to parts of Oregon, Kansas, and the Rocky Mountain 

 States. 



"Experience has shown that a deep retentive soil is capable of storing 

 a large quantity of water. On account of the fluctuation of western streams 

 of all kinds, from the small creek to the large river, the greatest flow of 

 water often comes at a season when there is least demand for it. In a few 

 localities adequate storage facilities have been provided to retain the 

 surplus, but as a rule it is allowed to go to waste. The passage of so much 

 waste water led to the introduction of winter irrigation and in nearly 

 every case the results have been satisfactory. The chief differences be- 

 tween winter and ordinary irrigations are the larger volumes used, the 

 crude manner of conveying and applying the water, and the dormant or 

 partially dormant condition of the plants at the time of irrigation. 



"Besides furnishing a supply of much-needed moisture, winter irrigation 

 when conditions are favorable, prevents winter killing and improves the 

 mechanical condition of the soil." 



6. Winterkilling of Alfalfa. 



"In the colder portions of Montana, Wyoming, Colorado, Utah, and the 

 Dakotas alfalfa is apparently winterkilled from a variety of causes and 

 sometimes from a combination of causes. The percentage of loss aiound 

 Greeley, Colo., has been placed at 2 per cent, per annum. In this locality 

 and throughout the Cache la Poudre Valley in northern Colorado most of 



