CHAPTEE VIII. 



COMPOUND MANUKES.i 



Manufacture of Mixed Manures. — The manures generally used foi" 

 admixture with superphosphates are Peruvian guano, bone dust,. 

 sulphate of ammonia and nitrate of soda, but the Peruvian guano dis- 

 patched from the spots of ]3roduction now is much less rich in nitrogen 

 than that imported in the past. Its place is taken by sulphate of 

 ammonia, ground horn, dried blood, dried meat, etc. Superphos- 

 phate of potash is also prepared. The mixing is done as much as 

 possible after the phosphate is dissolved. Mixing is not done ia 

 the dry state, except when it cannot be done otherwise. 



Hand labour is the best for this kind of work. The materials, 

 previously weighed and sifted, are made into a 2 ton heap by means 

 of a portable box (? barrow) capable of holding 100 kilos (2 cwt.).- 

 To turn the matter properly the shovel is plunged into it vertically,, 

 so as to mix it, then after having sifted it, it is made into a heap in 



1 In the wet mixing of compound manures where such things as sulphate 

 of ammonia, meat meal, fish guano, bone meal, kainit, shoddy, etc., go up the 

 cups, retrogradation is less marked. The other ingredients apparently, at 

 least, retard retrogradation, if they do not prevent it to a great extent. A 

 30 per cent soluble phosphate which retrograded 3 to 4 per cent in a few months 

 when dry mixed so as to give 20 per cent soluble phosphates and 7*0 per cent 

 ammonia, maintained that composition exactly for several months in a 250 ton 

 heap. It is better to use up superphosphates with such a marked tendency to 

 retrograde in the making of wet mixing compound manures. — Te. 



2 The British manure manufacturer works in cwts. to the ton, thus. 

 a very easy calculation shows that 8f cwts. of sulphate of ammonia (of 20*5 per 

 cent N) to the ton mixing, gives 9 per cent of nitrogen in the mixing ; a similar 

 easy calculation shows 11^ cwts. of superphosphate with 35 per cent of soluble 

 phosphate to the ton mixing, gives as near as may be 19-647 per cent of soluble 

 phosphate in the mixing, and 19-647 of soluble phosphate is equal to 9 per cent 

 of soluble phosphoric acid (9 x 2-183). 



It IS all very well for the author to say inert ingredients should not be used, 

 but it is often impossible to avoid the use of gypsum, the more so as it dries the 

 manure and gets the core through the screen. To get the core in this case through 

 the screen with bone dust would be a waste of money, as apparently no value 

 is attached to insoluble phosphate. Supposing the superphosphate used tests 

 in this case 38 per cent of soluble phosphate, it is a clear case for the addition 

 of gypsum instead of using two grades of superphosphate. Moreover, a manure- 

 of this nature with neither potash nor bone meal would have no backbone. — Tr. 



(142) 



