138 



PHOSPHATIC FERTILISERS 



[chap. 



of one series of the Rothamsted barley plots in 1893, ^ 

 specially dry season, and in 1894, ^vhich was almost 

 equally wet. 



The phosphoric acid increases the proportion of grain 

 to straw, and decreases the nitrogen content of the grain, 

 and it will be noticed that this latter effect is more 

 marked in the wet season of 1894. Even on the yield 

 itself the phosphoric acid had the greater effect in the 

 wet season. 



Exactly the same result can be observed in the 

 wheat crop, as may be seen in Table XXXV., which 

 gives the yield of grain and straw in 1879, the wettest 

 year in the Rothamsted records, and in 1893, which was 

 characterised by an extremely dry hot spring and 

 summer. 



Table XXXV.— Effect of Phosphokic Acid and Potash on the 

 Development of Wheat. Broadbalk Field, Rothamsted. 



In the wet year the use of phosphoric acid in- 

 creases the yield from 4-3 bushels with nitrogen only 

 to 1 1- 1 bushels with nitrogen and phosphoric acid, the 



