xii CONTEXTS 



CHAPTER in 



the function and comtakativk value of 

 nitro(;en()Us manures 



Nitrogen promotes the Wgetative Activity of the I'lanl— »'•*'■ 

 (irowth proportional t.. Niiro^jcn Supply— With Excess 

 of Nitrogen Maturity is deferred and the I'roportion of 

 Straw to (irain is increased— \'ariation of Composition 

 of Crop with Nitrogen Supply— Susceptibility of Plants 

 to Disease when supplied with Excess of Nitrogen — 

 Crops requiring Large Ouantities of Nitrogen — Relative 

 Availability of Nitrogenous Manures— Nitrate of Soda 

 ?'. Sulphate of Ammonia — Question to be decided by 

 the Nature of the Soil — Residues left by the Different 

 Nitrogenous Manures (ireatcr \'alue attached by 

 Farmers to Manures containing Nitrogen in Organic 

 Combination . , , .77 



ClIArTKR IV 



rHOSPHATIC MANURES 



The Phosphates of Calcium— The Early Use of Bones U 

 Manure —Preparation of Hone Meal and Steamed Hone 

 Flour — Dissolved Hones and Hone Comp>ounds — The 

 Discovery of Mineral Phosphates, Coprolites, Phos- 

 phorite, Pliosphatic Cluanos, Rock Phosphates — The 

 invention of Suf>erphosphate, Lawes and Liebig — The 

 Manufacture of Superphosphate — The Manufacture of 

 Hasic Slag — Nature of the Phosphoric Acid Compounds 

 in Basic Slag, their Solubility in Dilute Acid Solutions — 

 Basic Superphosphate — Wiborg Phosphate — Wolttr 

 Phosphate . . . ... 103 



CHAPTER V 



TlIK FUNCTION AND USE OF PHOSI'MATIC 

 FERTILISERS 



Ripening Effect of Phosphoric Acid — Most manifest in wet 

 Seasons — Effect of Phosphoric Acid in stimulating the 

 Formation of Roots and Adventitious Shoots — Associa- 

 tion of Phosphoric Acid with the Intake of Nitrogen by the 

 Plant— Solvents to determine the Relative Availability 

 of Phosphatic Fertilisers— Relative \'alue of Phosphatic 

 Fertilisers determined by the Soil— Soils appropriate to 



