CONTENTS xiii 



PART II. SOILS. 

 SECTION i. SOILS AND THEIR PROPERTIES. 



PAGE 



(a) Different kinds of soils and their physical properties .... 60 



(b) Relation of soil to water. Methods of modifying the water capacity of 



soils 67 



(c) The chemical properties of the different classes of soils ... 70 



(d) Useful and useless elements. Balance of fertilizers. Available and 



total plant food in soils ......... 72 



(<?) Relation of soil to air. Biological condition of soils. Fixation of 



nitrogen ........... So 



(/) The relation of soil to fertilizer 82 



(g) " The law of diminishing returns " from both its scientific and practical 



aspects 83 



References ............ 84 



SECTION 2. SPECIAL SOIL IMPROVERS. 



(a) Lime. Various forms of lime. Industrial waste lime. Gypsum and its 



special uses. Reasons why plastering has gone out of fashion . . 86 



(d) Electricity 89 



(c) The partial sterilization of soils. Application of heat. Germicides. Gas 

 lime. Naphthalene. Soil injuries. Effect of bad drainage. Injuries 

 due to unskilful cultivation ........ 90 



References . . . . . . . . . . . .92 



SECTION 3. SOIL RECLAMATION. 



(a) Barren lands. Causes of barrenness 93 



(b) Dry lands. Their treatment and improvement ..... 94 



(c) Wet lands. Their treatment and improvement .... 95 



(d) Peat. Its reclamation and improvement ...... 07 



References Ioo 



PART III. CROPS. 



SECTION i. PHOTOSYNTHESIS. 



The conversion of Solar energy into materials which in their turn develop 

 Animal energy. The materials in the crops produced by solar energy. 

 Their relationship to the fertilizers used. The economy in solar 

 energy obtained by the proper use of fertilizers . . . . . 101 



References .......... no 



