74 



The Sugar-Beet in America 



PLANT-FOOD REQUIREMENTS OF BEETS 



As previously stated, all crops use the same foods, but 

 they do not use these foods in the same proportion, and as 

 a result, the various crops have different fertilizer needs. 

 Of the seven mineral foods used by crops, all are present 

 in most soils in sufficient quantity to meet the needs 

 except nitrogen, potash, and phosphorus. In a few 

 exceptional soils other minerals are lacking, but they form 

 no important need. The following table gives the amount 

 of these scarce plant-foods used by sugar-beets in com- 

 parison with other crops : 



Table IV. 



Mineral Foods Removed from the Soil by 

 Crops 



This table shows that sugar-beets use relatively large 

 quantities of potash but not so much nitrogen or phos- 

 phoric acid. 



Studies of the effect of the various fertilizers on growth 

 have shown that excessive nitrogen stimulates leaf growth. 



