THE BEET-SUGAR INDUSTRY IN 1920. 27 



potash ; a corn crop, yielding 40 bushels of ears to the acre, will 

 require 56 pounds of nitrogen, 21 pounds of phosphoric acid, and 

 23 pounds of potash ; clover yielding 2 tons of hay per acre requires 

 83 pounds of nitrogen, 18 pounds of phosphoric acid, and 88 pounds 

 of potash. These elements are required by all field crops, and, in 

 addition to these, seven other elements are required in much smaller 

 quantities. These elements are always present in agricultural soils 

 in larger or smaller quantities. The two questions, therefore, with 

 regard to soil fertility, so far as the composition of the soil is con- 

 cerned, are whether the required elements are present in sufficient 

 quantity to produce the desired crop and whether the elements are 

 available or soluble in such quantity and at such time during the 

 growing season as the plant requires. In addition to the presence 

 of these elements, as indicated above, the soil must be in proper physi- 

 cal condition to promote plant growth in order to be fertile. In the 

 production of sugar beets a moderately fertile soil is required. If the 

 soil is lacking in fertility the roots may be too small to produce suffi- 

 cient tonnage to make the crop profitable to the grower. 



Under ordinary farm conditions there is little danger of the soil 

 being too fertile for satisfactory beet growing. Occasionally spots 

 are so fertile that large roots low in sugar are produced, as, for 

 example, an old feed lot, a barnyard which has been turned into a 

 portion of the field, or a spot where an old straw stack has been left 

 to decay. These areas are small and insignificant when compared 

 with the total sugar-beet acreage in the United States, but they 

 sometimes have an important bearing upon the results on an indi- 

 vidual farm, especially where the sugar-beet acreage on that par- 

 ticular farm is small. The greatest danger from the standpoint of 

 fertility arises from the lack of those phj^sical conditions or the 

 absence of available plant foods to produce large yields. The prin- 

 cipal problem, therefore, in this connection lies in the improvement 

 of the fertility of the soil. Soils may be rendered infertile through 

 natural causes, such as leaching, and through artificial causes, such as 

 single cropping, improper crop rotation, and the improper propor- 

 tion of live stock to crop production. One of the principal methods 

 that may be employed to increase soil fertility is the addition of 

 humus to the soil, either in the form of stable manure or of green 

 crops plowed under. 



Stable manure. — One of the most satisfactory methods of supply- 

 ing humus to the soil is the proper use of stable manure. A close 

 relation should exist between the number of live stock on the sugar- 

 beet farm and the acreage under cultivation. Studies in prac- 

 tically all parts of the sugar-beet area indicate that the number of 

 live stock on most farms is too small for the most profitable produc- 

 tion of crops and is usually below the possibilities in both live stock 



