xii CONTENTS 



PAGE 



(g) Organic Nitrogen Manures. Fish meal. Composition. Types of soil 

 and crop most suited. Objections and difficulties. Dried blood. Hoofs 

 and horns. Refuse oil cakes. Industrial waste materials ... 22 



References 24 



SECTION 2. THE PHOSPHORUS GROUP OF 

 FERTILIZERS. 



General properties. Chemical condition. The different phosphorus com- 

 pounds used as fertilizers . .... . . . 25 



(a) Basic Slag. History and development. Composition. Citric solubility. 



Fineness. Application to the soil. Soils most suited. Crops giving 

 good returns. Factors needed to ensure success. Secondary and 

 ultimate effects on the physical condition of the soil. Lasting effect . 27 



(b) Mineral Phosphates. Occurrence and distribution. Direct use on the 



land. Secondary effects. Water solubility. Citric solubility. Solu- 

 bility in other reagents. Reversion ...... 30 



(f) Fertilizers containing both Nitrogen and Phosphorus. Bones. Bone meal. 

 Bone flour. Dissolved bones. Guano. Mixtures to imitate guano or 

 dissolved bones. General considerations on time to apply mixed 

 nitrogen and phosphorus fertilizers. Their relative value and suitability 

 on different soils and to different crops ...... 32 



References 36 



SECTION 3. POTASSIUM GROUP OF MANURES 



German potash manures. Geological origin. Kainit. Muriate and sulphate. 

 Nitre. Wood ashes. Blast furnace dust. General reactions of potash 

 manures in the soil . . . . . . . . 37 



References . . ... 39 



SECTION 4. MIXED FERTILIZERS. 



(a) Containing nitrogen, phosphorus, and potassium. (Artificial mixtures) . 40 



(b) Farm-yard manure. Its constituents ; cow, pig, sheep, and horse dung. 



Urine of farm animals. Litter used in making manure. Physical 

 properties of litter . . , . .42 



(c) Nitrogen, phosphorus, and potassium. Passage from food to dung-heap. 



Relationship between type of food and type of beast and sort of manure 

 produced. Quantities made under varying conditions . . 48 



(d) Storage of manure. Denitrification. Drainage. Preservation. Effect 



of farm-yard manure on the soil. Valuation of farm-yard manure. 



Its lasting effects 5 



(e) Human excreta. Sewage. Sewage farms. Sewage sludge . . 54 

 (/) Poultry dung. Composts. Vegetable mould. Beech mast. Peat. 



Humogen. Seaweed . . . / -5" 

 References . 5 8 



