10 Feb. , 1911-] Examination of Artificial Manures. 



A popular question of the farmer is: — " Whose superphosphate is the 

 best? " It has often been rehited by wheat-growers that they have carried 

 out experiments wdth different brands of superphosphate and that the re- 

 sult from, one particular brand far eclipsed the rest. This fact, while 

 not being contradicted, may not have been due to the superphosphate it- 

 self, but more likely to a difference in the soil and a multitude of other 

 circumstances. 



The idea, which is vtTy prevalent amongst farmers, that different 

 brands of superphosphate supply different plant foods to the soil, may be 

 immediately di.smissed. The manufacture of all superphosj^hates of ordi- 

 nary standard has for its fundamental principle the solvent action of sul- 

 phuric acid on in.soluble rock phosphates. The product may differ slightly 

 in the percentage of fertilizing constituents, but the chemical compounds 

 present are alway.s the same. As far as quality from a chemical stand- 

 point is concerned, the farmer may look to the laboratory for assistance; 

 but for physical differences, i.e., the l)ehaviour of the manure in the drill, 

 he must rAlv on his own judgment. Tt should be mentioned here that 



bXLOADIXG KOCK PHO.Sl'UATE AT VAKRAVILLE. 



drills shouhl be thoroughly cleansed after use. Some manures are very 

 acid and tlic longer they are left in contact with a drilling machine the 

 shorter its life. 



Another common (|uery from northern farmers, who have the oppor- 

 tunity of oUserving large quantities of gypsum or copi being despatched to 

 the metropolis, is " Why are manufacturers allowed to adulterate with 

 gypsum?" They state, in sfime instances, that the gypsum, which occurs 

 as deposits on or near their holdings, after being consigned to Melbourn'- 

 and then trrattil with an acid, returns to them as superphosphate. This 

 is altogetlier incorrect. Others, say that tlie gyjjsum is mixetl witli su|)er- 

 phos])hate. which is afterwards i)ur(hased by tlicni. and tliey contend that 

 the " mi.xing business " can just as reathly .md ciiraply Ik- prrformetl b\ 

 themselves. 



The gypsum despatched to Melbourne is largely sold as a texture in"- 

 pro\er for stiff soils, as a remedy in clover sickness, as a deodori/er in 

 stables, and I have e\iMi heard of ii being used in making a tennis coui' 

 It is certainly usetl as an admixture in most of the iione b-rtilizers. I ; 

 rarely in oIIkt manures. allhnu;/h one manufacturer used it in the '' l^o; >• 



