FOOD REQUIREMENTS OF CROPS 



265 



toes by Lawes and Gilbert, using different manures, 

 gave the following results: 78 



AVERAGE YIELD PER ACRE FOR 12 YEARS 



Potatoes require liberal general manuring reenforced 

 with wood ashes or other potash fertilizer. In the rota- 

 tion they should follow grain or pasture, provided the 

 fertility of the soil is kept up. Commercial fertilizers 

 for potato production should contain a fair amount of 

 available nitrogen (2 to 3 per cent) and a more liberal 

 supply of phosphoric acid and potash. See Section 



324- 



316. Sugar Beets. This crop is more exacting in its 

 food requirements than any other root crop. Excessive 

 fertility is not conducive to a high content of sugar. 

 Soils in good mechanical condition and medium state 

 of fertility usually give the best results. 79 Sugar beets 

 should not receive heavy dressings of stable manure, 

 because an abnormal growth results. Nitrogenous fer- 

 tilizers may be applied only in limited amounts, heavier 



