XII CONTENTS 



CHAPTER IV 



ULLAGE AND THE MOVEMENTS OF SOIL WATER 



PAGE 



Water required for the Growth of Crops The Effect of 

 Drainage Effects of Autumn and Spring Cultivation, 

 Hoeing and Mulching, Rolling, upon the Water Con- 

 tent of the Soil The Drying Effect of Crops Bare 

 Fallows Dry Farming Effect of Dung on the Reten- 

 tion of Water by the Soil ..... too 



CHAPTER V 



THE TEMPERATURE OF THE SOIL 



Causes affecting the Temperature of the Soil Variation 

 of Temperature with Depth, Season, etc. Tempera- 

 tures required for Growth Radiation Effect of Colour 

 Specific Heat of Soils Heat required for Evapora- 

 tion Effect of Situation and Exposure Early and Late 

 Soils . . . . . . '35 



CHAPTER VI 



THE CHEMICAL ANALYSIS OF SOILS 



Necessary Conventions as to the Material to be Analysed 

 Methods Adopted Interpretation of Results Dis- 

 tinction between Dormant and Available Plant Food 

 Analysis of the Soil by the Plant Determination 

 of "Available" Phosphoric Acid and Potash by the 

 Use of Weak Acid Solvents . . . 159 



CHAPTER VII 



THE LIVING ORGANISMS OF THE SOIL 



Decay and Humification of Organic Matter in the Soil 

 Alinit The Fixation of Free Nitrogen by Bacteria 

 living in Symbiosis with Leguminous Plants Soil 

 Inoculation with Nodule Organisms Fixation of Nitro- 

 gen by Bacteria living free in the Soil Nitrification 

 Denitrification Protozoa Iron Bacteria Fungi of Im- 

 portance in the Soil : Mycorhiza, and the Slime Fungus 

 of " Finger-and-Toe " ...... 192 



