FERTILIZERS FOR VEGETABLES 



219 



high temperature, in bright sunshine and with lack of mois- 

 ture at some period of growth. 



Size is due largely to generous feeding with nitrogen, other 

 essential conditions being favorable. 



The keeping quality of some vegetables may be very ma- 

 terially affected by nitrogen feeding. For example, cab- 

 bages grown with large amounts of nitrogen are all right for 

 immediate consumption and of delicious crispness, but their 

 keeping quality is impaired. For immediate consumption 

 one can, therefore, use larger amounts of nitrogen than when 

 the crop is to be stored for a considerable length of time. 



Phosphorus. 



The special interest of phosphorus to the vegetable grower 

 is its effect upon the germination of seeds. Available phos- 

 phorus compounds containing calcium, like acid phosphate, 

 favor rapid development of the young seedlings by stimulat- 

 ing the growth of roots and thus giving the young plant a 

 good start. Under favorable conditions this early start may 

 materially shorten the time in which the crop matures. 



Potassium. 



For the vegetable grower, potassium is of interest on ac- 

 count of its influence upon the formation of carbohydrates, 

 such as starch, sugar and cellulose. With insufficient sup- 

 plies of available potassium compounds, we cannot obtain 

 starch or sugar. Sugar is, of course, of special importance 

 in peas, sweet corn, melons, turnips, beets, etc. In this con- 

 nection, a word will not be out of place in regard to the sweet- 

 ness of parsnips, potatoes and similar products which have 

 been subjected to low temperature. The starch in tubers 

 and roots that are stored is converted into sugar slowly, and 

 at ordinary temperatures this sugar is used up in respiration 

 processes; but at low temperatures at which the change of 

 starch into sugar goes on, respiration stops and the sugar ac- 

 cumulates. It is for this reason that parsnips, for example, 

 need to be subjected to low temperatures before they become 

 sweet. 



The question has often been asked as to the comparative 

 value of sulphate of potash and muriate of potash in the pro- 



