MIXTURES FOR CROPS 209-219 Composition of plant not a guide 209 The multiplication of formulas 209 A few combinations are safest 210 Amount of application 211 Similarity of requirements 213 Maintaining fertility 215 Fertilizer for grass 216 All the nitrogen from clover 218 Method of applying fertilizers 218 An excess of nitrogen 219 CHAPTER XXI TILLAGE 220-229 Desirable physical condition of the soil 220 The breaking-plow 221 Types of plows 221 Subsoiling 223 Time of plowing 223 Method of plowing 224 The disk harrow 225 Cultivation of plants 227 Controlling root-growth 227 Elimination of competition 228 Length of cultivation 229 CHAPTER XXII CONTROL OF SOIL MOISTURE 230-236 Value of water in the soil 230 The soil a reservoir 231 The land-roller 232 The plank-drag 233 The mulch 233 Mulches of foreign material 234 Plowing straw down 235 The summer-fallow 235 The modern fallow 236 CHAPTER XXIII DRAINAGE 237-246 Underdrainage 237 Counting the cost 238 Where returns are largest 239 Material for the drains 239 The outlet 240 Locating main and branches 240 The laterals 241 Size of tile 241 Kind of tile 242 The grade 243 Establishing a grade 243 Cutting the trenches 244 Depth of trenches 245 Connections 245 Permanency desired 246 ILLUSTRATIONS Alfalfa and Corn in Indiana _Frontispiece_ Facing Page A Good Crop for a Poor Soil 4