68 



SOIL CONDITIONS AND PLANT GEO WTH 



wines contain most PgO^ (about 0-3 grm. per litre), the second 

 and lower qualities containing successively less. Further, 

 when the vintages for different years were arranged in order 

 of their PgO^ content a list was obtained almost identical with 

 the order assigned by the wine merchants. Davis (78^) has 

 emphasised the importance of phosphate supply for the indigo 

 crop. 



52*56 57'6I 627l 72'8I 82'9I 92*01 02'll I3'l9 



Fig. I2A. — Effect on yield of grain of withholding various nutrients from 

 barley. (Hoos field, Rothamsted.) 



The close connection between cell division and phosphate 

 supply may account for the large amount of phosphorus com- 

 pounds stored up in the seed for the use of the young plant, 

 and also the relatively large amounts of phosphate taken 

 from the soil during the early life of the plant. 



Potassium. — Hellriegel has shown (Table IV., p. 31) that 



