i8 FERTILISERS AS AN AID TO 



Whether phosphates are supplied to the soil 

 in a water-soluble form or otherwise, they do 

 not leach or wash away in the 

 Drainage water like nitrates, but are 

 retained in the soil. The researches 

 of Way, Voelcker, and, more recently, Dyer on 

 Rothamsted soils, which had been receiving as 

 much as 3^- cwts. of high grade superphosphate 

 for very many years, have proved most con- 

 clusively that the unconsumed phosphoric acid 

 was practically all retained in the surface soil 

 to the depth of 9 inches, and was also in such 

 a form as could be readily assimilated by the 

 plant roots. From this it is abundantly evident 

 that an excess of phosphates can do no possible 

 harm to the crops and is never wasted. More- 

 over, it also shows that superphosphate can be 

 advantageously applied much earlier than is 

 generally done; in fact, if applied in the autumn, 

 when there is usually sufficient rain to dissolve 

 and distribute it thoroughly, better results are 

 likely to follow than when applied late in 

 spring. 



In addition to water-soluble phosphate, super- 

 phosphates always contain some citric soluble 

 phosphate, approximately i to 2 per cent., some- 

 times even more, which is just as valuable as 

 the " soluble " phosphate in basic slag. It is 

 not generally known that this is not taken into 

 account by the manufacturers in fixing the price 

 of superphosphate, so that our farmers unwit- 

 tingly get the benefit of it, though in other 

 countries its value is recognised. 



