xii CONTENTS 



CHAPTER III 



THE FUNCTION AND COMPARATIVE VALUE OF 

 NITROGENOUS MANURES 



Nitrogen promotes the Vegetative Activity of the Plant — p^<^" 

 Growth proportional to Nitrogen Supply — With Excess 

 of Nitrogen Maturity is deferred and the Proportion of 

 Straw to Grain is increased — Variation of Composition 

 of Crop with Nitrogen Supply — Susceptibility of Plants 

 to Disease when supplied with Excess of Nitrogen — 

 Crops requiring Large Quantities of Nitrogen — Relative 

 Availability of Nitrogenous Manures — Nitrate of Soda 

 V. Sulphate of Ammonia — Question to be decided by 

 the Nature of the Soil — Residues left by the Different 

 Nitrogenous Manures — Greater Value attached by 

 Farmers to Manures containing Nitrogen in Organic 

 Combination . . . . . . yj 



CHAPTER IV 



PHOSPHATIC MANURES 



The Phosphates of Calcium — The Early Use of Bones as 

 Manure — Preparation of Bone Meal and Steamed Bone 

 Flour — Dissolved Bones and Bone Compounds — The 

 Discovery of Mineral Phosphates, Coprolites, Phos- 

 phorite, Phosphatic Guanos, Rock Phosphates — The 

 Invention of Superphosphate, Lawes and Liebig — The 

 Manufacture of Superphosphate — -The Manufacture of 

 Basic Slag — Nature of the Phosphoric Acid Compounds 

 in Basic Slag, their Solubility in Dilute Acid Solutions — 

 Basic Superphosphate — Wiborg Phosphate — Wolter 

 Phosphate ....... 103 



CHAPTER V 



THE FUNCTION AND USE OF PHOSPHATIC 

 FERTILISERS 



Ripening Effect of Phosphoric Acid — Most manifest in wet 

 Seasons— Effect of Phosphoric Acid in stimulating the 

 Formation of Roots and Adventitiotis Shoots — Associa- 

 tion of Phosphoric Acid with the Intake of Nitrogen by the 

 Plant — Solvents to determine the Relative Availability 

 of Phosphatic Fertilisers — Relative Value of Phosphatic 

 Fertilisers determined by the Soil — Soils appropriate to 



