IS 
Research Bulletin So. 3 
arid region of summer-rains in the United States indicated that 
the generalizations previously shown to apply to studies of soil 
moisture in Saskatchewan were equally applicable to the whole 
of the semiarid region of summer rainfall from the Saskatchewan 
River on the north to the Mexican boundary on the south. "The 
depth to which samples should be taken should extend at least 
as far as the plants develop roots freely or as far as the moisture 
descends from the surface. This depth can in most cases be 
approximately determined by a field examination of the soil. 
Soils of this region are characterized by their ability to be 
reduced by the native vegetation and by many annual crop plants 
to a characteristic easily recognized, dry condition. This state 
of dryness seems the normal condition in the more southerly 
regions, while in the most northerly it may be found only at the 
time of the maturing of the plants. This property facilitates in 
most cases the ready recognition of the moisture condition by a 
mere field examination with the soil auger." 
RECENT STUDIES BY BRIGGS AND SHANTZ. 
Briggs and Shantz 1 have recently published the results of an 
extensive series of pot experiments in which they have fully 
utilized the results of all previous studies along the same line. 
Also, they have applied the conclusions arrived at from these 
pot experiments to field studies of soil moisture, but have as 
yet published but few data on the latter. In their pot experi- 
ments they have, like Heinrich, used small glass vessels 2 and 
allowed the soil to become as thickly penetrated by roots as 
possible, after which it has been allowed to stand fully pro- 
tected from evaporation until the plants wilted permanently. 
The per cent of water remaining in the lower two-thirds of the 
soil mass, where the roots are most abundantly developed, they 
designate the wilting coefficient. 
They have met the various obstacles that stood in the way of 
accuracy by various ingenious methods. Further, they have at- 
tempted to determine the relation which holds between the wilt- 
p. 698. Photograph reproduced in Widtsoe's "Dry Farming," 1911, p. 96. 
The data of the experiment described below as that of 1909 (page 33) 
were presented in the paper. 
1 Briggs, L. J., and Shantz, H. L. A Wax Seal Method for Determining 
the Lower Limit of Available Soil Moisture, Botanical Gazette 51, 1911, p. 
210. — The Wilting Coefficient and its Indirect Determination, Botanical 
Gazette 53, 1912, p. 20— The Wilting Coefficient for Different Plants and 
its Indirect Determination, Bui. 230, Bureau of Plant Industry, U. S. Dept. 
of Agriculture, 1912. — Application of Wilting Coefficient Determinations in 
Agronomic Investigations, American Society of Agronomy, November, 
1911. vol. 3, p. 257. 
2 Briggs and Shantz have used ordinary drinking glasses. 
