THE BEET-SUGAR INDUSTRY IN THE UNITED STATES. 25 



there must be more or less alkali dissolved in the water. As this 

 water rises to the surface of the soil it brings with it the salts held 

 in solution. After the water evaporates from the surface of the 

 soil the alkali remains, and it may eventually accumulate to such 

 an extent that crop production is greatly reduced or rendered 

 entirely impossible. This condition is a limiting factor in the pro- 

 duction of sugar beets as well as other crops in certain portions of 

 the sugar-beet area. The sugar beet is one of the most alkali resistant 

 of our farm crops, but even with this plant the limit of endurance 

 is sometimes reached or exceeded, and beet growing becomes un- 

 profitable. Alkali in the seed bed is especially troublesome, since 

 the young plants are very tender and therefore susceptible to this 

 and other adverse conditions. If the beet plants are well started 

 before the alkali accumulates in the surface soil, much less damage 

 will be done, as the subsequent growth of the plants is less affected 

 by the same amount of .alkali. The alkalinity of a soil may be 

 reduced by the use of irrigation water, provided the irrigating water 

 is comparatively free from alkali and a satisfactory drainage system 

 has been established. 



FERTILITY. 



Elements of plant growth. — By fertility in this connection is meant 

 the ability of the soil to produce a good crop. The difference between 

 a rich soil and a fertile soil should be kept in mind — that is, a soil is 

 rich if it contains a considerable quantity of each of the elements 

 required by the plant in the process of growth. Unless, however, 

 these elements are available to the plant and the physical conditions 

 of the soil are such as to promote plant growth, the soil can not be 

 said to be fertile. If a single element required by the plant, though 

 present, is not soluble, this condition will render the soil infertile. 

 In order that an element may be available to the plant, it must be 

 soluble, and it must dissolve rapidly enough to supply the plant with 

 that particular element as rapidly as the plant requires it. Certain 

 elements are always available when present; other elements must be 

 acted upon by certain substances under certain conditions in order to 

 become available or soluble. It is apparent, therefore, that fertility 

 is one of the limiting factors in the production of sugar beets as well 

 as of other crops. 



The sugar beet requires the same elements of plant food that are 

 required by other field crops, but in slightly different proportions; 

 for example, a 10-ton crop of sugar beets (which is approximately 

 the average yield for the United States) will require about 30 pounds 

 of nitrogen, 14 pounds of phosphoric acid, and Tl pounds of potash ; 

 a wheat crop, yielding 20 bushels per acre, will require 41 pounds 

 of nitrogen, about 13 pounds of phosphoric acid, and 17 pounds of 

 63212°— 18— Bull. 721- — 4 



