PART II

Soil fertility as affected by farm operations and
farm practices

Chapter Page

  XVI.—­A fertile soil 141
        Physical properties: 
          Power to absorb and hold water
          Power of ventilation
          Power to absorb and hold heat 142
        Biological properties 143
          Nitrogen-fixing germs 144
          Nitrifying germs 145
          Denitrifying germs 147
        Chemical properties: 
          Nitrogen in the soil
          Phosphoric acid in the soil
          Potash in the soil
          Lime in the soil
          Great importance of physical properties 147
        Maintenance of fertility 150

XVII.—­Soil water                                            151
Importance of soil water                              151
Necessity of soil water                               151
Sources and forms of soil water                       153
Too much water                                        154
Not enough water                                      154
Loss of soil water                                    155
How some farm operations influence soil water         156
Hoeing, raking, harrowing and cultivating             158
Manures and soil water                                159
Methods of cropping and soil water                  159
Selection of crops with reference to soil water     160

XVIII.—­The after-cultivation of crops 164
        Loss of water by evaporation 164
        Loss of water through weeds 165
        Saving the water 165
        Time to cultivate 166
        Tools for after-cultivation 167
        Hilling and ridging 169

XIX.—­Farm manures                                          171
The functions of manures and fertilizers              171
Classification                                        171
Importance of farm manures                            172
Barn or stable manure                                 173
Loss of value                                         173
Checking the losses                                   176
Applying the manure to the soil                       177
Proper condition of manure when applied               179
Composts                                              181