applied 179
Composts 181

XX.--FARM MANURES, CONCLUDED 183
Green-crop manures:
Functions 183
Benefits 185
Character of best plants for green-crop manuring 185
The time for green-manure crops 186
Leguminous green-manure crops 186
Non-leguminous green-manure plants 191

XXI.--COMMERCIAL FERTILIZERS 192
The raw materials 192
Sources of nitrogen 193
Sources of phosphoric acid 195
Sources of potash 199
Sources of lime 200

XXII.--COMMERCIAL FERTILIZERS, CONTINUED 202
Mixed fertilizers:
What they are
Many brands
Safeguard for the farmer
Low grade materials
Inflating the guarantee 202
Valuation 205
Low grade mixtures 207
Buy on the plant food basis 209

XXIII.--COMMERCIAL FERTILIZERS, CONCLUDED 211
Home mixing of fertilizers 211
Kind and amount to buy 212
The crop 213
The soil 215
The system of farming 215
Testing the soil 215

XXIV.--ROTATION OF CROPS 219
Systems of cropping 219
The one crop system 221
Rotation of crops 224
Benefits derived from rotation of crops 230
The typical rotation 231
Conditions which modify the rotation 232
General rules 233
Lengt