20 THE CONNECTICUT AGEICULTUEAL 



EXPLANATIONS OF FERTILIZER- ANALYSIS AND VALUATION. 



Nitrogen is commercially the most valuable fertilizing element. 

 It occurs in various forms or states. Organic nitrogen is the 

 nitrogen of animal and vegetable matters generally, existing in 

 the albumen and fibrin of meat and blood, in the uric acid of bird 

 dung, in the urea and hippuric acid of urine, and^n a number of 

 other substances. Some forms of organic nitrogen, as that of 

 blood and meat, are highly active as fertilizers ; others, as that of 

 hair and leather, are comparatively slow in their eff'ect on vegeta- 

 tion unless these matters are reduced to a fine powder or chemi- 

 cally disintegrated. Ammonia and nitric acid are results of the 

 alteration of organic nitrogen in the soil and manure heap, and are 

 the most, active forms of Nitrogen. They occur in commerce — 

 the former in sulphate of ammonia, the latter in nitrate of soda. 



17 parts of ammonia, or 66 parts of pure sulphate of ammonia 

 contain 14 parts of nitrogen. 



85 parts of pure nitrate of soda also contain 14 parts of nitrogen. 



Soluble Phosphoric acid implies phosphoric acid or phosphates 

 that are freely soluble in water. It is the characteristic ingre- 

 dient of Superphosphates, in which it is produced by acting on 

 " insoluble" or " reverted" phosphates with oil of vitriol. It is 

 not only readily taken up by plants, but is distributed through 

 the soil by rains. Once well incorporated with soil it shortly be- 

 comes reverted phosphoric acid. 



Reverted {reduced or precipitated) Phosphoric acid strictly 

 means phosphoric acid that was once freely soluble in water, but 

 from chemical change has become insoluble in that liquid. It is 

 freely taken up by arstrong solution of ammonium citrate, which 

 is therefore used in analysis to determine its quantity. " Re- 

 verted phosphoric acid" implies phosphates that are readily 

 assimilated by crops, but generally have less value than soluble 

 phosphoric acid, because they do not distribute freely by rain. 



Insoluble Phosphoric acid implies various phosphates not freely 

 soluble in water or ammonium citrate. In some cases the j)hos- 

 phoric acid is too insoluble to be rapidly available as plant food. 

 This is true of South Carolina rock phosphate, of Navassa phos- 

 phate, and esjDecially of Canada apatite. The phosphate of 

 coarse raw bones is at first nearly insoluble in this sense, because 

 of the animal matter of the bone which envelopes it, but when 

 the latter decays in the soil, the phosphate remains in essentially 

 the " reverted" form. 



