Fruit 136


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