CONTENTS 



CHAPTER VIII 



PERUVIAN GUANO AND OTIIKR MIX'FD 

 FERTILISERS 



Origin of the Deposits of Guano — Variation in Composition '*•»■ 

 with Age— Compounds of Nitrogen present in Peruvian 

 C'iuano — Ichaboe and Dan^ar.iland (iuanos — Fi»h 

 Guano— Meat Ciuano— Dried Illoo<l— Greaves -Rape 

 Dust and other Cake Residues— Manures derived from 

 Kxcal Matter— Scwa^je Sludges . 229 



CHAPTKR IX 



MATERIALS OK INDIRhXT FERTILISING VALUE 



Lime— Early Use of Lime— White and Grey Limes— Lima 

 Ashes— Marl — Chalk— Ground Limestone — Indications 

 of the I^ck of Lime in the Soil— Artmn of Lime upon 

 the Soil— Improvement of Texture— Promotion of the 

 Oxidation of nitrogenous Residues in the Soil — Increase 

 in the Availability of Phosphoric Acid and Potash- 

 General Action of Soluble Salts on the Soil— Gas 

 Lime — Gypsum — Salt — Sulphate and Carbonate of 

 Magnesia — Sulphate of Iron ; Supposed Connection of 

 Iron in the Soil with the Colour of Fruit and Flowers- 

 Manganese Salts— Silicates— Green Manuring— Folding 

 Catch Crops on the Land ..... 249 



CIIAl'TKK X 

 THEORIES OF FERTILISER ACTION 



I iebig's Ash Theory— Part played by the Soil in the Nutrition 

 of the Crop— Ville's Theory of Dominants — Liebi^'s 

 Law of the Minimum -I^iw of diminishing; Returns- 

 Limiting Factors in Plant Growth- Is the Composition 

 of the Soil Water unaffected by Fertilisers?— Attack of 

 the Plant's Roots upon Insoluble Fertilisers— The Part 

 played by Carbon Dioxide in the Soil— Excretion of 

 Toxic Substances from Plant Roots — Rotations as a 

 Sub>titute for Fertilisers — Unexplained Factors in the 

 Nutriliou Problem ...... 376 



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