lo Jan., T912.] Artificial Manures Acts. 25 



nitrogen is widely distributed through the animal and vegetable kingdom, 

 and its chief source for manurial purposes is from blood, bones, and other 

 organic substances. 



Nitrogen as ammonia is obtained chiefly from the destructive distillation 

 of coal in gas manufacture. It combines with an acid radicle forming 

 sulphate of ammonia, and in this form it is more readilv soluble than 

 organic nitrogen. 



Nitrogen as nitrate is found in natural deposits in South America. 

 It exists as nitrates of soda and potash. Like ammonium- sulphate, it is 

 completely soluble in water and diffuses readily through the soil. It is 

 available as food to the plant without further change. 



Phosphoric acid is derived from phosphates, the chief source of which, 

 is phosphate of lime. It occurs in fertilizers in three forms, which are 

 distinguishable by their solubility (water-soluble, citrate-soluble, and in- 

 soluble), and these terms express the forms in which phosphoric acid is 

 readily available, moderately so, or difficultly so, respectively. 



The first mentioned form is, of course, soluble in water, the second is 

 the portion soluble in citrate of ammonia after the extraction of tlie water 

 soluble content. Citrate soluble form is generally considered to be avail- 

 able as plant food, and is of importance in arriving at the value of a 

 fertilizer. The insoluble phosphoric acid is not of .any immediate value to 

 the plant, its action on soils is slow, and its value doubtful. Experience 

 has shown the necessity of fertilizers which are immediately available to 

 the plant, and for this reason insoluble phosphate is treated with sulphuric 

 acid, and .so converted into soluble superphosphate. 



Bonedusts contain phosphoric acid and nitrogen, the phospboric acid 

 content being insoluble in water ; but, in a finely divided state, the particles 

 have more surface exposure, and, consequently, decav quicker and become 

 available to the plant. The fineness of a bonedust has, therefore, an 

 important bearing on its availability. 



Bone fertilizers are distinct from bonedusts, in that some are composed 

 of bonedust, animal refuse, ground phosphate rock, and generally super- 

 phosphate, while others are bonedusts diluted with gypsum. 



Ground phosphates and guanos differ from the organic phosphates such 

 as bonedusts and animal fertilizers. They contain practically no organic 

 matter, are denser in structure, and, except in extreme cases, they are not 

 used to any extent without treatment with acid. They are used as raw- 

 material for the manufacture of superphosphates. 



Thomas phosphate is the by-product obtained in the manufacture of 

 steel, through the use of phosphatic iron ore. The phosphoric acid content 

 is more readily soluble than in bones or rock phosphates. 



Potash is obtained from natural deposits, and is supplied in the 

 form of sulphate and chloride (muriate). Both forms are readily 

 soluble. 



The following is a list of fertilizers registered in the ofiice of the 

 Secretary of Agriculture for the year 191 2, showing the particulars of 

 each manure, as required by the Artificial Manures Acts, to be published 

 in the Government Gazette. 



