139-148
Controlling factors 139
Direct use for corn 140
Effect upon moisture 141
Manure on grass 142
Manure on potatoes 143
When to plow down 144
Heavy applications 144
Reenforcement with minerals 145
Durability of manure 147

CHAPTER XV

CROP-ROTATIONS 149-158
The farm scheme 149
Value of rotation 150
Selection of crops 151
An old succession of crops 152
Corn two years 153
The oat crop 154
Two crops of wheat 154
The clover and timothy 154
Two legumes in the rotation 155
Potatoes after corn 156
A three-years' rotation 157
Grain and clover 158
Potatoes and crimson clover 158

CHAPTER XVI

THE NEED OF COMMERCIAL FERTILIZERS 159-170
Loss of plant-food 159
Prejudice against commercial fertilizers 160
Are fertilizers stimulants? 161
Soil analysis 162
Physical analysis 163
The use of nitrogen 164
Phosphoric-acid requirements 165
The need of potash 166
Fertilizer tests 167
Variation in soil 168

CHAPTER XVII

COMMERCIAL SOURCES OF PLANT-FOOD 171-187
Acquaintance with terms 171
Nitrate of soda 171
Sulphate of ammonia 178
Dried blood 173
Tankage 174
Fish 175
Animal bone 175
Raw bone