CULTURAL DIRECTIONS 459 



a shortage of the mineral elements, invariably result in 

 a heavy growth of vine and foliage and a light crop of 

 small fruits. While nitrogen is essential, it should be 

 used in moderation. Its value is greatest early in the 

 season, before the organic forms have had time to be 

 changed by nitrification into nitrates. Numerous experi- 

 ments show the value of spring applications of nitrate 

 for this crop. Such treatment encourages a vigorous vine 

 growth before the fruits begin to color and in most in- 

 stances has been the means of increasing the yield. Not- 

 withstanding the beneficial results arising from the use 

 of nitrate of soda, it is admitted that part of the nitrogen 

 should be derived from an organic form, as dried blood, 

 tankage and fish scrap. For the late crop the soluble 

 forms of nitrogen are not so useful, and yet in thin soils 

 they may be employed to advantage. 



The mineral elements must also be supplied in ample 

 quantities, for without them the fruits will be small and 

 inferior and the crop light. There should be a proper 

 proportion of the three elements applied. This will 

 doubtless vary greatly in different soils, or even on the 

 same type, the amount of each to use depending upon 

 previous methods of cropping and of soil treatment. 



A knowledge of the composition of the fruit and the 

 vines assists in the determination of a satisfactory com- 

 bination of fertilizing ingredients. Voorhees ("Fertiliz- 

 ers," p. 233) estimates a ton of the fruit and vines to 

 contain the following amounts of nitrogen, phosphoric 

 acid and potash: 



COMPOSITION OF TOMATOES 



Nitrogen Phosphoric Pota5& 



acid 

 Ibs. Ibs. Ibs. 



In fruit 3.20 i.oo 5.40 



Vines (green) 6.40 1.40 10.00 



He estimates that a yield of 10 tons an acre, with vines 



