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Sulphate of Ammonia. Supplies one of the cheapest forms of 

 nitrogen in the market. When pure, contains 24 to 25 per cent, of 

 ammonia, equivalent to 20 of nitrogen, and is one of the most 

 concentrated forms of nitrogen available. It is obtained from coal 

 gasworks and extracted from the gas liquor, and is purified of the 

 ammonia thiocyaiiate (a plant poison) it contains before being 

 put in the market. As it is not quite so soluble as nitrate of 

 soda, it is not so liable to be washed out of the soil as are nitrates, 

 A simple test for showing the absence of most, at any rate, of the 

 impurities with which sulphate of ammonia is likely to be 

 adulterated is to throw a pinch of the sulphate on a red hot iron 

 plate ; the sulphate of ammonia, if pure, will be quickly volatilised 

 and dissipate entirely. Applied at the rate of J to Ifcwt. per acre 

 in the spring, mixed with some dry, well-ground material such as 

 sand, earth, or other fertilisers, so as to ensure its even distribution. 



Nitrate of Soda. As imported from Chili, contains rather more 

 than 15 per cent, of N. or 18 to 19 per cent, ammonia. Its price 

 is almost prohibitive in Australia. More soluble than sulphate of 

 ammonia, and for this reason especially useful in a dry season, 

 owing to its being deliquescent. Applied at the rate of \ to If cwt. 

 per acre in the spring, mixed with some dry, well-ground material, 

 so as to ensure its even distribution. 



Soil or manure analysis often express the nitrogenous contents 

 as nitrogen or as ammonia. And in order to better understand 

 the difference between the amount of each, it is useful to remember 

 that 17 parts of ammonia (NH 3 ) contain 14 of nitrogen (N) and 

 that 66 parts of pure sulphate of ammonia, or 85 parts of nitrate of 

 soda, also contain 14 parts of nitrogen. Excess of organic nito- 

 genous manures, it should be borne in mind, are often productive of 

 harm, and cause such diseases as " die back" of the trees. In white- 

 ant infected districts it must also be used with caution. " I have 

 used sheep manure for orange trees," writes a Narra Tarra fruit 

 grower ; "it acts very well, but proves a hotbed for white ants." 



Phosphorus is, next to nitrogen, the most costly ingredient of 

 fertilisers, in which it occurs in the form of phosphates of lime, 

 iron, and aluminium, or, in case of superphosphates, partly as free 

 phosphoric acid. In good soils it rarely exceeds 2 per cent. 



The trade uses with regard to phosphoric acid several terms 

 which to the layman are not very familiar, thus : 



Soluble phosphoric acid implies phosphoric acid or phosphates 

 that are soluble in water or in a solution of ammonium citrate. It 

 diffuses into the ground and thus reaches the feeding rootlets of the 

 crop instead of lying inert in the soil, as do the mechanically-mixed 

 insoluble phosphates, until the rootlets find them out and attack 

 them. 



Insoluble phosphoric acid requires a stronger solvent than 

 ammonium citrate to make it available as plant food. 



