Investigations at Burlingtoti, Colorado. 



69 



surface foot than those of wheat. Great mats of branches occurred in the 

 surface 6 to 12 inches of soil, forming a profoundly developed absorbing 

 system on all sides of the plant, even to a distance of 1 to 1.2 feet. The 

 working depth was about 2.5 feet, while some roots reached a maximum 

 of 2.9 feet, where they encountered the very dry hardpan. 



Alfalfa, Medicago sativa. 



Alfalfa was sowed at Burhngton at the same time as the cereals already 

 described, on April 15. On June 11, when the roots were examined, the 

 plants were about 4.5 inches high, although the tallest ones reached 6 inches. 

 The stand was quite good, and the plants had a normal green color, but some 

 wilted badly during the hottest part of the day. Hardpan occurred in this 

 plat at 2.2 feet depth. While the surface 6 inches of soil was very dry, below 

 this a small amount of available water occurred to the hardpan layer (table 

 17). Most of the roots were about 1.7 feet deep, although some were traced 



Fig. 31. — Alfalfa excavated at Burlington, June 28, 1921, during the second year 



of growth. 



to 2.3 feet. The root habit, especially in the surface soil, was quite Uke that 

 described at Lincoln, but in the deeper layers the roots were found to be more 

 abundantly branched. Moreover, the branches were longer and extended 

 nearer the root-ends. 



A second examination was made on July 7, when the crop was about 5 

 inches high. Considerable variation in the development of the plants was 

 noticeable, however, many being much smaller than the average and a few 

 8 inches tall. The trench was only a few feet from the preceding and the 

 hardpan occurred at 2.1 to 2.3 feet depth. The soil, and especially the 

 surface 8 inches, was very dry. Roots were abundant to the hardpan layer, 

 but none extended beyond. They were characterized by a much more 

 profuse branching than was found at Lincoln, and the lateral spread was 

 also much greater. Undoubtedly this root habit is an adaptation to secure 



