TABLE OF CONTENTS xvil 



PAGES 



— Utilization of humus compounds by plants, 419 — 

 Sodium nitrate, 420 — Ammonium sulfate, 421 — Ferti- 

 lizers containing atmospheric nitrogen, 422 — Cyanamid, 

 423 — Composition of cyanamid, 424 — Changes of cal- 

 cium cyanamid in the soil, 425 — The use of cyanamid, 

 426 — Calcium nitrate, 427 — Organic nitrogen in ferti- 

 lizers, 428 — Availability of organic nitrogenous ferti- 

 lizers, 429. 



Fertilizers Used for their Phosphorus. 



Bone phosphate, 430 — Mineral phosphates, 431 — 

 Superphosphate fertilizers, 432 — Reverted phosphoric 

 acid, 433 — Relative availability of phosphate fertilizers, 

 434 — Changes that occur when superphosphate is added 

 to soils, 435 — Other factors influencing the availability 

 of tricalcium phosphate, 436 — Effect of plants on the 

 availability of tricalcium phosphate, 437 — Effect of 

 basicity on tricalcium phosphate, 438 — Influence of fer- 

 menting organic matter, 439 — Influence of other salts, 

 440. 

 Fertilizers Used for their Potassium. 



Stassfurt salts, 441 — Wood ashes, 442 — Insoluble 

 potassium fertilizers, 443. 

 Sulfur and Sulfates as Fertilizers. 



The use of free sulfur, 444 — Sulfur as sulfate, 445. 

 Catalytic Fertilizers. 



Nature of catalytic action, 446 — Catalytic action of 

 soils, 447 — Substances used as catalytic fertilizers, 448 



— Manganese, 449 — Physiological role of manganese, 

 450 — Action of manganese as a fertilizer, 451 — Forms 

 of manganese and response of soils, 452. 



CHAPTER XXIV 



Soil Amendments 534-545 



Salts of calcium, 453 — Effect on tilth and bacterial 

 action, 454 — Liberation of plant food materials, 455 — 

 Influence of lime on the formation of nitrates in soil, 456 

 — Effect on toxic substances and plant diseases, 457 — 



