202 Fertilizers 



Root crops. 



Another class of plants, differing from those already 

 described, includes the root crops, as beets, mangels, 

 turnips and carrots. These plants cannot make ready 

 use of the insoluble mineral constituents of the soil. 

 Hence, in order to insure full crops, they must be liberally 

 supplied with available food. Of the three classes of fer- 

 tilizing constituents, the phosphates are especially useful 

 for turnips, while the slower-growing beets and carrots 

 require that the nitrogen shall be in quickly available 

 forms. The proper fertilization of sugar beets, for exam- 

 ple, is of great importance, since not only is the yield 

 affected by fertilization, but the quality of the beet for the 

 production of sugar. 



White potatoes and sweet potatoes, the one a tuber, the 

 other an enlarged root, constitute another class which does 

 not possess strong foraging powers. They require their 

 food in soluble and available forms, and with suitable soils 

 potash is the ingredient that is especially useful in the 

 manures applied. 



Markefyarden crops. 



Another group of crops is distinguished as a class, not so 

 much because of their peculiar habits of growth as because 

 of the objects of their growth, though this latter fact has a 

 very important bearing upon economical methods of fer- 

 tilization. This class includes what are called "market- 

 garden crops/' as lettuce, beets, asparagus, celery, turnips, 

 cucumbers, melons, sweet corn, beans, peas, radishes and 

 various others. The particular object in raising these is to 

 secure rapidity in growth, and thus to insure high quality, 

 which is measured by the element of succulence. In order 



