98 The Principles of Vegetable- Gardening 



nitrogen, potash and phosphoric acid removed from an acre; 

 then the amount of these materials recommended by Voorhees 

 (in his book on " Fertilizers ")> and others and the differences 

 between the two : 



Supposing that the crop obtains none of its nitrogen, potash 

 and phosphorus from the soil, it will be seen that the fertilizer 

 recommended for cabbage is 57 Ibs. in excess of the needs of 

 a normal crop, and for fancy sweet potatoes 200 Ibs. in excess. 

 Yet it is probable that the recommendations are perfectly safe 

 and economical, for the grower wants an extra rather than a 

 good yield, he wants the crop early and quick-growing, and he 

 wants to take no risk of failure. In parsnips and carrots, the 

 recommended amounts are less than those required by the crop ; 

 but in these cases earliness is not a prime requisite, and the 

 plant is supposed to draw slowly a large part of its supply from 

 the stored food in the soil. 



Another difficulty in the giving of advice for ferti- 

 lizing the land is the variable character of the soil. 

 This is particularly the case in the northern states, in 

 which the soil is largely drift and is therefore very 

 uneven in kind and depth. In the long stretches of 

 sand on* the Atlantic coastal plain or in the red clays 

 of the South, and in nearly all alluvial soils, the prob- 

 lem of choosing a fertilizer is less complex. The sandier 

 and more uniform the land, the more marked, as a 

 rule, will be the effect of commercial fertilizers. The 



