xxii CONTENTS 



PAGE 



Studying fertiliser tags . ..... 368 



Some guarantees misleading . ..... 368 



Repetitions in guarantees . - . . . . . 369 



The forms of phosphoric acid ...... 370 



Calculating the value of a fertiliser ..... 373 



Low-grade fertiliser expensive ...... 375 



The advantages of home mixing ..... 376 



Sources of nitrogen ....... 377 



Sources of phosphoric acid ...... 379 



Bone fertiliser ........ 379 



Rock phosphates . . . . . . .381 



Phosphate slag 381 



Superphosphates ....... 382 



Sources of potash ........ 384 



Mixing the raw materials ... . . . . 386 



What kinds of fertiliser to use ...... 388 



Soil analyses as a guide to fertilising .... 389 



Questioning the soij ....... 390 



The needs of different crops ..... 392 



The relative importance of the three plant foods . . 394 



When to apply fertilisers . . . . . . . 395 



The solubility of the fertiliser 395 



The needs of the crop . . . . . .896 



How to apply fertilisers ....... 396 



When it will pay to use fertilisers ..... 398 



Indirect fertilisers . ....... 399 



The benefits of liming 399 



Lime a plant food ....... 399 



Improves texture ....... 899 



Unlocks potash ........ 400 



Sweetens sour soils . . - . . . . . 400 



The soils that need liming ...... 400 



Tests for sour soils . . . . . . . .401 



Land plaster, marl and other amendments . . . 402 



APPENDIX 



I. Crop rotations in the different states. . . . 405 



II. Analyses of soils ....... 417 



III. Native plant food in farm soils. . . . .419 



