8 CHEMICAL FERTILIZERS 



be much modified by vigorous oxidation of organic matter in 

 the soil; some of the beneficial actions of organic matter 

 in the soil must be attributed to this action. Since bacterial 

 action in the soil may easily be very markedly influenced by 

 increasing the supply of phosphoric acid and nitrogen, the 

 amount of carbonic acid in the soil will also be indirectly 

 modified by the application of chemical fertilizers; hence 

 it comes about that the addition of one element of plant food 

 in the form of a plant fertilizer may easily render available 

 some other element, provided the soil was already fairly 

 rich in that material. 



REFERENCES TO SECTION I. 



Brown and Escombe, " On the Variations in the Amount of Carbon 

 Dioxide in the Air at Kew, during the Years 1898 to 1901." Proceedings 

 of the Royal Society, 1905, p. 118. 



Bayliss, " The Nature of Enzyme Action," p. 39 (Longmans, Green 

 & Co.). 



Deventer, " Physical Chemistry for Beginners," p. 117 (Arnold). 



Dyer, " Available Mineral Plant Food," Journ. Chem. Soc., 1894, p. 116. 



Collins, " Plant Products," p. 77 (Bailliere, Tindall and Cox). 



Warrington, " The Chemistry of the Farm " (Vinton). 



Voelcker, " The Woburn Pot Experiments," /. Bd. Agric., Aug. 1913, 

 p. 421 ; " Influence of Magnesia on Wheat and Mangolds," Journ. Roy. 

 Agric. Soc., 1914, and /. Bd. Agric., Aug. 1915, p. 465. 



Hall, " The Book of the Rothamsted Experiments," p. ix (Murray) ; 

 " The Soil," p. 35 % :(Murray). 



Johnson, " How Crops Grow " (Orange Judd). 



Leather, " Water Requirements of Crops in India " (Thacker, Spink). 



