264 REPORTS ON THE STATE OF SCIENCE.—1914. 
dry-land conditions ; while the Office of Biophysical Investigations, in co- 
operation with the above-named offices, is concerned with the study 
of the influence of various tillage methods on the absorption and reten- 
tion of rainfall, the water requirement of crops under field conditions, 
and the influence of climatic conditions on the growth of dry-land 
crops. Over 50,0001. is now appropriated annually by Congress for 
the support of the dry-land work. In addition to this, several of 
the States are also conducting dry-farming investigations on an exten- 
sive scale, either independently or in co-operation with the Govern- 
ment. The field of investigation is so extensive that the present paper 
will be confined largely to the biophysical phases of the work. 
Dry-Farming Areas in the United States. 
Two great dry-farming areas occur in the United States. One, 
the Intermountain area, lies between the Rocky Mountains on the 
east and the Sierra Nevada Mountains on the west. It is essen- 
tially a region of winter and spring rainfall. The other, the Great 
Plains area, extends from the Canadian boundary along the eastern 
side of the Rocky Mountains nearly to the Mexican boundary, and 
embraces over 200,000 square miles of land whose productivity is 
limited by the rainfall. This area, in contrast to the other, is a 
region of summer rainfall. 
These two great areas differ greatly in their physiographic features 
and in their native plant cover. The Intermountain district is broken 
into numerous valleys, and the vegetation consists mainly of shrubby 
perennial plants, such as the sage-brush (Artemisia tridentata) 
(Plate V.) and a salt-bush (Atriplex confertifolia). The size and 
character of this vegetation affords a good index of the productivity 
of the land.'. The larger the sage-brush the greater the water-supply 
and the better the farm. The soils occupied by salt-bush, on the other 
hand, are apt to be so saline in character as to be unsuited to dry- 
farming. 
In the Great Plains no trees or shrubs are found except along 
the water-courses, while the gently undulating, grass-covered plain 
stretches unbroken to the horizon save for the buildings of the settlers. 
Much of this country is covered with buffalo grass (Buchloé dacty- 
loides) and grama grass (Boueteloua oligostachya) (Plate V.), while 
farther to the east, where the rainfall is somewhat heavier, the taller 
bunch grass (Andropogon scoparius) and wire grass (Aristida 
longisela) make their appearance.? This striking difference in the 
vegetation, characterised by the shrubby plants in the Intermountain 
districts and by grasses on the plains, reflects the difference in the dis- 
tribution of the annual rainfall, which has had a marked effect upon 
the dry-farming development of the two sections. 
1 “Tndicator Significance of Vegetation in Tooele Valley, Utah,’ Kearney, Briggs, 
Shantz, McLane, and Piemeissel, Journal of Agricultural Research, United States 
Department of Agriculture, 1, p. 365, 1914. 
? Shantz, H. L., Natural Vegetation as an Indicator of the Capabilities of Land 
for Crop Production in the Great Plains Area, U.S. Department of Agriculture, Bureau 
of Plant Industry, Bulletin 201, 1911. 
