Dry-Farming

,000 square miles. This immense territory is far from being a vast level plain. On the extreme east is the Great Plains region of the Mississippi Valley which is a comparatively uniform country of

th of the Great Basin are the high plateaus, into which many great chasms are cut, the best known and largest of which is the great Canon of the Colorado. North and east of the Great Basin is the Columbia River Basin characterized by basaltic rolling plains and broken mountain country. To the west, the floor of the Great Basin is lifted up into the reg

stribution of land and water, elevation, prevailing winds-swing between such large extremes that of necessity the climatic conditions of diff

ict, which receives from 20 to 30 inches of rainfall annually; over the Rockies themselves, semiarid conditions prevail; in the Great Basin, hemmed in by the Rockies on the eas

stribution

at the most desirable season, will have greater crop-producing power than a very much larger rainfall poorly distributed. Moreover, the methods of tillage to be employed where most of the precipitation comes in winter must be considerably different from those used where

monthly distribution o

y of the United State

recognizes five dist

ific, (3) Arizona, (

n Foothills, and (5

hing characteristic of the Pacific type is a wet season, extending from October to March, and a practically rainless summer, except in northern California and parts of Oregon and Washington. About half of

ences that control the precipitation of this region are much similar to those that prevail west of the Sierra Nevada and Cascade ranges. There is not,

ls over Arizona, New Mexico, and a small portion of eastern Utah and Nevada. This type differs from all others in the fa

y allied to that of the plains to the eastward, and the bulk of the rain falls

all the great corn and wheat states of the interior valleys. This region is characterized by a scant winter precipitation over

ers rainless; while east of the Rockies, the winters are somewhat rainless and the precipitation comes chiefly in spring and summer. The Arizona type stands midway between these types. This variation in the distribution o

ow

er is benefited if it comes in the form of snow. The fall-planted seeds are better protected by the snow; the evaporation is lower and it appears that the soil is improved b

annual temperature is high. The heaviest snowfall is in the intermountain district, from the west slope of the Sierra Nevadas to the east slope of the Ro

per

and parts of California and Arizona as warm. The range in temperature from the highest in summer to the lowest in winter is considerable, but not widely different from other similar parts of the United States. The range is greatest in the interior mountainous districts, and lowest along the seacoast. The daily range of the highest and lowest temperatures for any one da

ts are ordinarily so far apart as to allow an ample growing season. It must be remembered that frosts are governed very largely by local topographic features, and must be known from a local point of view. It is a general law that frosts are more likely to occur in valleys than on hillsides, owing to the downward drainage of the coo

ive h

ages of the quantity required for saturation. A relative humidity of 100 per cent means that the air is saturated; of 50 per cent, that it is only one half saturated. The drier the air is, the more rapidly does the water evaporate into it. To the d

h humidity at all seasons, the percentage o

n eastward to the Atlantic coast, the a

ning portion of the elevated district, between the 100th meridian on the east to the Sierra Nevada and the Cascades on the west, varies between 55 and 65 per cent. In July, August, and September, the mean values in the Southwest sink as low as 20 to 30 per cent,

arried by the air of the humid states. This means that evaporation from plant leaves and soil surfaces will go on more rapidly

ns

ation of water from the soil. The whole dry-farm territory receives more sunshine than do the humid sections. In fact, the amount of sunshine may roughly

i

effect of wind on any farming district. Local observations, however, may enable the farmer to estimate the probable effect of the winds and thus to formulate proper cultural means of protection. In general, those living in a district are able to describe it without special observations as windy or quiet. In the dry-farm territory of the Unite

mm

ght winter precipitation. Snow falls over most of the territory, but does not lie long outside of the mountain states. The whole dry-farm territory may be classed as temperate to cold; relatively high and persistent winds blow only over the Great Plain

ing, often carelessly agricultural methods developed in humid sections, have foun

ou

with causing drouths, but under the above definition, man is usually the cause. Occasionally, relatively dry years occur, but they are seldom dry enough to cause crop failures if proper methods of farming have been practiced. There are four chief causes of drouth: (1) I

r any crop injury resulting from drouth. A fairly accurate knowledge of the climatic conditions of the district, a good understanding of the principles of agriculture w