the winterkilling is done in open dry winters and is quite generally at- 

 tributed to a scarcity of moisture in the soil. In the winter of 1907 con- 

 siderable damage was done to the 'alfalfa fields around Loveland, Colo., 

 on account of the long dry spell in midwinter. The old alfalfa fields suf- 

 fered most. It was the opinion of the farmers that a late fall irrigation 

 would have prevented the loss. 



"Near Wheatland, Wyo., the higher portions of the fields suffer most 

 damage in winter, and here also the cause is said to be lack of moisture in 

 the soil, combined with the effects produced by cold and wind. 



"At Choteau, in northern Montana, a farmer watered, late in the fall, 

 part of an alfalfa field which was 2 years old, and it winterkilled, while 

 the unwatered portion escaped injury. This and other evidence along the 

 same line which might be given go far to demonstrate that under some 

 conditions too much moisture is as detrimental as too little. 



"Probably the chief cause of the winterkilling of alfalfa is alternate 

 freezing and thawing. The damage from this cause is greatly increased 

 when any water is left standing on the surface. A blanket of snow is a 

 protection, but when a thin sheet of ice forms over portions of a field the 

 result is usually fatal to plants. The bad effects of alternate freezing and 

 thawing on alfalfa may be observed at the edge of a snow bank. This 

 crop is likewise injured by the rupture of the tap roots caused by the 

 heaving of the soil. 



"Prom present knowledge of the subject, the means which may be used 

 to protect alfalfa fields from winterkilling may be summed up as follows: 

 Where both the soil and the air are dry the plant should be supplied with: 

 sufficient water for evaporation, but the land should be drained so thor- 

 oughly that none of the top soil is saturated; a late growth should not be 

 forced by heavy irrigations late in the growing season; if the soil is dry, 

 irrigate after the plants have stopped growing; and the latest growth 

 should be permitted to remain on the ground, unpastured, as a pro- 

 tection. 



"It may be stated in conclusion that the loss to the farmer from the 

 winterkilling of alfalfa is not as great as might appear at first. The dam- 

 age is done in winter, and there is ample time to plow the plants under and 

 secure another crop, which is usually heavy, owing to the amount of 

 fertilizers added by the roots of alfalfa. The Montana farmer who in- 

 creased his average yield of oats from 50 to 103 bushels per acre by 

 ploughing under winterkilled alfalfa illustrated this point." 



7. Seeding Alfalfa on Land to Be Irrigated. 



"In the upper Snake River Valley, in Idaho, alfalfa is usually preceded 

 by a grain crop. The stubble is plowed 6 to 9 inches deep in the fall, and 

 early in the spring it is double-disked, harrowed, and smoothed. Prom 8 

 to 20 pounds of seed is then drilled in 0.75 inch to 1.5 inches deep in rows 

 6 inches apart. When oats is used as a nurse crop it is seeded first, 80 

 to 100 pounds per acre being used. Prom 8 to 12 pounds of alfalfa seed 

 are then drilled in, in the opposite direction. Some farmers use a com- 

 bination drill which seeds both at the same time. When no nurse crop is 

 used the alfalfa plants are clipped when they reach a height of 8 to 12 

 inches. This is necessary to hold the weeds in check and to cause the 

 plants to Btool. 



"In the Yakima Valley, March and April are preferred for seeding 

 alfalfa, both on account of the climate and the abundant water supply of 

 that period. The ground is plowed deep, graded, smoothed, and harrowed. 

 From 10 to 20 pounds of seed are then put in with a broadcast seeder and 

 harrowed lightly. The furrows are then marked off and irrigation begins. 

 The ground is kept moist constantly until the young plants are fairly well 

 established. The use of so much water at the start is due largely to the 

 tendency of the soil to bake if allowed to become dry. 



"The alfalfa growers of Montana are about equally divided in opinion 

 as to the advantages of using a nurse crop. Those who seed grain with 

 alfalfa claim that they get more out of the land the first season, whi 

 those who are opposed to this practice believe that the injury done to the 

 alfalfa plants by the grain crop extends through several years and that 

 the small gain of the first year is more than offset by the lessened yields 

 of alfalfa in subsequent years. 



