l88 THE FORAGE AND FIBER CROPS IN AMERICA 



24 inches of water to produce the three crops usually grown. 

 No rule, however, can be laid down as to the amount of water 

 required, since this will depend on the climate, soil, and position 

 of the ground water. Indeed, in many instances the ground 

 water at a depth of from four to twelve feet constantly fed by 

 seepage from rivers or canals is sufficient for the growth of 

 alfalfa without irrigation. The water is usually applied by the 

 system known as flooding, from two to ten hours being required. 

 The amount should not be sufficient to allow pools of water to 

 stand after the water is turned off, else the alfalfa will be killed. 



212. Rotations. The economic duration of an alfalfa field 

 varies greatly with climate and soil. The author saw a field 

 in Nevada which had grown alfalfa 18 years continuously with- 

 out re-seeding or the addition of seed. Grass was somewhat 

 abundant, but satisfactory crops of alfalfa were still being 

 harvested. Usually other things equal, the largest yields are 

 obtained the second and third years (third and fourth from 

 seeding), while thereafter there is a decrease in yield from 

 the gradual dying out of plants. The rotation practised around 

 Greeley, Colorado, where potato growing is an important in- 

 dustry, is about as follows : potatoes two years ; wheat one 

 year; barley or oats, with which the alfalfa is seeded, one year; 

 alfalfa three to four years. 1 Wing recommends for humid 

 sections: maize one year; barley, with which alfalfa is seeded, 

 one year; alfalfa four years. 2 For eastern Kansas five or six 

 years of alfalfa followed by cereals in rotation for twenty years 

 is recommended. By having five fields, one field or one-fifth 

 of the farm may be in alfalfa all the time. 



213. Quantity of Seed. While 25 plants to the square foot 

 is considered an excellent stand for a new seeding, and in old 

 meadows good yields of hay may be obtained with five plants 



1 U. S. Dept. Agr. Yearbook 1904, p. 313. 



* Pennsylvania State Dept. Agr. Bui. No. 129. 



