74 COTTON CULTURE 



Phosphoric Acid is expressed as: (a) Phosphoric Acid, 

 (6) Soluble Phosphoric Acid, (c) Reverted Phosphoric 

 Acid, (d) Available Phosphoric Acid, (e) Soluble and 

 Available Phosphoric Acid, (/) Insoluble Phosphoric Acid, 

 (g) Total Phosphoric Acid, (h) Phosphoric Acid equal (or 

 equivalent) to Bone Phosphate of Lime. 



Nitrogen is expressed as: (a) Nitrogen, (6) Ammonia, 

 (c) Nitrogen equal (or equivalent) to ammonia. 



POTASH 



(a) Potash, as used in connection with fertilizers, al- 

 ways means a compound containing potassium and oxygen, 

 known chemically as potassium oxide. Potash is never 

 found as such in fertilizers, but chemists, when expressing 

 the results of analyses, use this form as a convenient stand- 

 ard for reference. Fertilizers generally contain potash in 

 such forms as sulfate of potash, muriate of potash, or 

 carbonate of potash. Instead of stating .the amount of 

 sulfate, muriate, or carbonate of potash present in a fer- 

 tilizer, in giving the results of analyses, its equivalent 

 amount is stated only in the form of actual potash. 



(b) Potash actual is simply another name for potash, 

 as distinct from sulfate, muriate, etc. 



(c) Potash S. (or Sul.), means sulfate of potash. This 

 is quite often used by manufacturers in giving guarantees. 



(d) Potash soluble represents the amount of potash 

 that dissolves in water and is available for the use of plants. 

 The different forms of potash commonly used in ferti- 

 lizers are readily soluble in water. 



