CONTENTS xili 



Superphosphate — Fate of Superphosphate applied to ^''^^ 

 the Soil — Soils appropriate to Basic Slag — Neutral 

 Phosphatic Manures for Light Soils — Comparison of 

 Bone Meal with other Phosphatic Fertilisers . .136 



CHAPTER VI 



THE POTASSIC FERTILISERS 



Early Use of Wood Ashes — The Stassfurt Deposits — Manu- 

 facture and Composition of Commercial Potash Fertilisers 

 — The Retention of Potash by the Soil — The Function 

 of Potash in the Nutrition of the Plant — Dependence of 

 Carbohydrate Formation upon Potash, as illustrated in 

 the Barley and Mangold Crops — The Action of Nitrate 

 of Soda upon Insoluble Potash Compounds in the Soil — 

 Potash Fertilisers as promoting the Growth of Legu- 

 minous Plants — Effects of Potash Starvation upon 

 Vegetation — Potash as a Preventive of Fungoid Disease 

 — Potash as prolonging the Growth of the Plant — 

 Destruction of the Tilth of Clay Soils by Potash Salts — 

 Soils deficient in Potash . . . , .158 



CHAPTER Vn 



FARMYARD MANURE 



Variable Composition of Farmyard Manure — The Fate of the 

 Constituents of Food during Digestion and Excretion — 

 Composition of Urine and Fasces of Farm Animals — 

 Fermentation Changes taking place during the Making 

 of Dung — The Breakdown of the Nitrogenous Bodies 

 and of the Carbohydrates — Gases found in the Dunghill 

 — Losses of Nitrogen during the making of Farmyard 

 Manure — Preservatives used to minimise the Losses 

 during Dung-making — Composition of Farmyard Manure 

 — Cake-fed v. Ordinary Manure — Long and Short 

 Manure — London Dung — The Value of Fresh Manure — 

 The Fertilising Value of Farmyard Manure — Recovery 

 of its Nitrogen in the Crop — Long Duration of the Action 

 of Farmyard Manure — Farmyard Manure as a Carrier 

 of Weeds or Disease — The Physical Effects of Farmyard 

 Manure upon the Soil — The Improvement in Texture 

 and Water- retaining Power — Value of Farmyard Manure 

 as a Mulch on Grass Land — Farmyard Manure best 

 utilised for the Root Crop or Grass Land — Value of 

 Farmyard Manure : Cost of making One Ton . . 178 



