COMMERCIAL FERTILIZERS 59 



may be able to harvest several crops from the same 

 ground in one season, to clear the land in time to start 

 a cover crop or mature a green manurial crop before 

 cold weather, and to secure far better quality than is 

 possible when the growth is slow. The quality of many 

 vegetables is closely associated with rapidity of growth. 

 A slow growth is likely to cause a bitter flavor in lettuce, 

 a sharp flavor in onion and a pungent flavor in radish. 

 Again, slow growth is certain to cause greater develop- 

 ment of fiber, making the vegetables tough, woody or 

 stringy. A rapid growth usually secures succulence, 

 crispness and palatability. And, in addition, rapid-grow- 

 ing vegetables are less subject to injury from insects and 

 diseases than are slow-growing ones. 



105. The use of nitrogen. Of the three elements sup- 

 plied by commercial fertilizers to garden crops, nitrogen 

 is more frequently the limiting factor than either potash 

 or phosphoric acid, because in cultivated soils it is lost 

 more quickly and, also, because it is more expensive to 

 buy, and therefore likely to be supplied in less 

 abundance. Nitrogen plays the most important part in 

 the growth of leaves and succulent stems, and therefore 

 it is particularly valuable in the production of such crops 

 as cabbage, lettuce, brussels sprouts, spinach, kale, Swiss 

 chard, endive, celery, sweet corn and asparagus. Also, 

 large amounts of nitrogen are very necessary in growing 

 onions. 



Nitrogen is valued largely according to its availability. 

 For this reason nitrate of soda is considered by commer- 

 cial growers the most valuable nitrogenous fertilizer. 

 It is available to the plant as soon as dissolved, while 

 stable manures, dried blood, tankage, bone meal and other 

 organic materials must rot or decay before they are of 

 any benefit as plant foods. For the money invested 

 probably no other fertilizing material is capable of giv- 

 ing such large net returns, provided all conditions are 



