28 FERTILIZERS 



while the muriate or chloride form does. The sul- 

 phate can also be used as a "fixer" of ammonia in 

 stables and manure pits, while the muriate might 

 cause the escape of ammonia. 



AVAILABILITY. 



42. Buyers of fertilizers should always know the 

 source and form of the different plant foods. This 

 knowledge and the results obtained will determine 

 their availability. Nitrogen from nitrate of soda is 

 the most available form of any. Nitrogen from 

 blood is more available than that from tankage. 



Phosphoric acid from acid phosphates (rock or 

 bone) is more soluble than the non-acid phosphates. 



Steamed bone finely ground is more soluble than 

 raw bone, as the latter is seldom finely ground. 



43. All nitrogenous substances become available 

 easily. The most highly nitrogenous are the most 

 readily available. For this reason it is difficult to 

 say whether steamed bone or raw bone as a source 

 of phosphoric acid is most readily available. The 

 former is always more finely ground and the latter 

 always higher in nitrogen, but as raw bone is usually 

 quite coarsely ground, it is less readily acted upon 

 by the various divSsolving agents of the soil, notwith- 

 standing its higher nitrogen content. The phos- 

 phoric acid from tankage is more available than 

 that from raw bone. Both the nitrogen and phos- 

 phoric acid, as found in animal tankage and guanos, 

 finely ground are very available forms. 



44. Soil moisture, root acids and fermentation, 

 are the dissolving agents in all soils. The high tem- 

 peratures of summer increase their action. Humus 

 is essential to fermentation and to the carbonic acid 

 in soil water which is a very active solvent, 



