. Western agriculture. harmful practice illustrates the way in which alkalisoils are formed. When water is applied to soil, it tends byforce of gravity to sink to lower levels. In so doing it seeksthe larger openings and spaces in the soil; so water may passdown through the soil without becoming very heavily chargedwith soluble substances from it. When the water evap-orates from the surface of the soil, that from the lower depthstends to rise to the surface to take the place of the waterevaporated. As the soil water gradually climbs to the sur- 146 ALKALI SOILS 147 face, it becomes laden with
. Western agriculture. harmful practice illustrates the way in which alkalisoils are formed. When water is applied to soil, it tends byforce of gravity to sink to lower levels. In so doing it seeksthe larger openings and spaces in the soil; so water may passdown through the soil without becoming very heavily chargedwith soluble substances from it. When the water evap-orates from the surface of the soil, that from the lower depthstends to rise to the surface to take the place of the waterevaporated. As the soil water gradually climbs to the sur- 146 ALKALI SOILS 147 face, it becomes laden with soluble constituents. These,as the water evaporates, are deposited at the surface inquantities sufficient to act as a poison to the plant. Thereare numerous examples of this throughout Montana, Idaho,Utah, Colorado, California, and other western states. Appearance. Soils which have been the shore of a seaor lake may also be so charged with soluble salts as to beclassified as alkali soils. These have been formed by the. Figure 40.—Alkali spots in alfalfa field. The evaporation of the surface water hasbrought the alkali to the surf ace. Grand Junction, Colo. (Photo by E. D. Ball.) evaporation of the water which has covered them, while thesalts of the water have been deposited on the soil. Many ofthe alkali soils of the Great Basin have been formed throughthe slow evaporation of the waters of Lake Bonneville. Thetwo classes of soils are, however, distinct in their true alkali soils are, after reclamation, extremely fertile,but the lake shore soils may or may not be; and these latterare usually much more difficult to reclaim than the districts vary from a spotted field, in which onlya small area is affected, to the one which is a barren soil may have a brownish tint, appearing as if oil hadbeen poured over its surface or it may be so covered with 148 WESTERN AGRICULTURE salts that it is white. A white soil, however, does not neces-sarily
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectagriculture, bookyear
