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 diarp 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. 
Nitrate of soda and sulphate of ammonia are con- 
sidered by commercial growers the most valuable nitro- 
genous fertilizers for quick results, since they are avail- 
able to the plant as soon as dissolved, while stable ma- 
nures, 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 prob- 
ably no other fertilizing materials are capable of giv- 
ing such large net returns, provided all conditions are 
