UNITED STATES DEPARTMENT OF AGRICULTURE 
BULLETIN No. 1087 
Washington, D. C. 
PROFESSIONAL PAPER 
November 3, 1922 
ALFALFA ROOT STUDIES. 
By Samuel Gakver, Assistant Agrostologist, Office of Forage-Crop Investiga- 
tions, Bureau of Plant Industry. 
CONTENTS. 
Page. 
Scope of the study 1 
Factors tending to produce modifi- 
cations of root growth 2 
Soil conditions 2 
Climatic conditions 3 
Cultural factors--— 3 
Abnormalities due to injuries — 6 
Varieties studied 9 
Conditions under which varieties 
were grown 10 
Difficulties encountered in getting 
comparable data 11 
Page- 
Characteristic root systems of some 
of the well-known varieties of 
alfalfa 12 
Nonhardy alfalfas 13 
Common alfalfas 14 
Turkestan alfalfa 18 
Grimm alfalfa 19 
Yellow-flowered alfalfa 21 
Summary 24 
Bibliography 27 
SCOPE OF THE STUDY. 
Only within recent years have the crown and the root characters 
of alfalfa been extensively studied and their relation to environ- 
mental factors carefully considered. The physical reasons for an 
alfalfa plant being resistant to cold or drought remain much in 
doubt, but the studies of various investigators tend to substantiate the 
general belief that they may be associated with broad, deep-set crowns, 
well-developed rooting rhizomes, and numerous branch roots. The 
publicity that has been given to these particular features has created 
the rather general impression that there is a much greater difference 
in the crown and root characters of the hardy and nonhardy alfalfas 
than actually exists. Plants with pronounced taproots are generally 
well enough adapted to regions with relatively high mean tempera- 
tures, while plants with the more branching root systems are less sub- 
ject to winterkilling and to injury by rodents or cultivation. The 
broad, deep-set crowns that are usually associated with the branching 
root system are popularly considered a decided advantage in cold re- 
103923°— 22 1 
