270 REPORTS ON THE STATE OF SCIENCE.—1914. 
spring rains have ceased, the stubble and the early growth of weeds 
are turnedunder, and the land is kept fallow until the following 
autumn. The low rainfall during the summer makes it possible to 
destroy the weed-growth and maintain an efficient surface-mulch at 
a comparatively low cost. In the autumn, wheat is again sown. The 
crop makes a good part of its growth while the temperature is cool 
and the evaporation low, and in addition to the stored moisture has the 
advantage of the seasonal precipitation during its growth period. 
One serious difficulty in dry-farming operations in regions of winter 
rainfall occurs in connection with the seeding of winter wheat on fallow 
land. The surface-mulch of the fallow is often dust-dry in the fall to 
a depth of 4 inches or more. If the farmer drills his grain in the 
dust, the seed remains inert until a rain occurs. If the first rain is 
insufficient in amount to soak through the dry mulch to the damp soil 
below, the seeds germinate, but the rootlets of the seedling plants do 
not reach the stored moisture below the intervening dry layer, and the 
plants soon die. On this account, farmers usually wait for fall rains 
before sowing wheat. If the seeding is thereby delayed until late in 
the fall, and freezing weather follows, the young plants are injured and 
weakened. And if this is followed by an ‘ open winter,’ so that the 
wheat plants are not protected by a covering of snow, ‘ winter killing’ 
is often very severe, and the crop is practically a failure. 
Drilling the wheat to a depth sufficient to place the seed in moist 
soil would appear to be a possible solution of this problem, but this is 
often found impracticable, and the seedling plants have great difficulty 
in forcing their leaves to the surface. It is possible that a solution of 
the difficulty may be found in a seed-drill which has recently been 
developed, which throws the dry surface-soil in ridges, and plants the 
grain in moist soil at moderate depths in the intervening furrows. This 
plan is not practicable in windy regions, for the furrows would soon 
fill with dry soil. 
In striking contrast with Intermountain practice, spring wheat is 
grown extensively in the Great Plains, especially in the central and 
northern part. The spring-sown crop escapes the dry fall and all 
danger from winter-killing, while the land, having been recently 
worked, is in better condition to absorb the summer rainfall. Inter- 
tilled crops are also grown to a much greater extent than in the 
Intermountain district, maize being especially popular in the northern 
part of the Great Plains, and the non-saccharine sorghums (milo, kafir, 
sorgo) in the southern part. The intertilled crop has in many sections 
largely taken the place of fallow, spring wheat now being extensively 
grown on disked corn-land. 
Fallow.is used extensively in the Great Plains, but the experiments 
by the Office of Dry-Land Agriculture, under the direction of E. C. 
Chilcott,’ have shown that alternate cropping and summer tillage in 
many sections is less profitable than simple three-year rotations, 
especially those in which spring wheat is grown on disked corn-land, and 
even less profitable than continuous cropping. Summer tillage is not 
8 A Study of Crop Rotations and Cultivation Methods for the Great Plains Area, 
U.S. Department of Agriculture, Bureau of Plant Industry, Bulletin 187, p. 8, 1910. 
