136 AGRICULTURE 



The alkaline character of basic slag places 

 it in a superior position for use on a cruci- 

 ferous crop which it is intended to grow 

 on land known to be affected by finger-and- 

 toe. Experiments have shown that this 

 disease is encouraged by acidity in the soil, 

 and superphosphate cannot fail to increase 

 acidity to a greater or less degree, whereas 

 basic slag tends to counteract it. 



This prejudicial effect of the acidity of 

 superphosphate is so generally recognized 

 that a manure, known as Basic Superphos- 

 phate, has been placed on the market, the 

 main character of which is that, by the 

 addition of lime in the process of manu- 

 facture, the originally water-soluble phos- 

 phate has been rendered insoluble, while the 

 acidity has been more than neutralized. The 

 insoluble phosphate thus formed is known 

 as " reverted " phosphate, which, although 

 insoluble in water, is soluble in a 2 per cent, 

 solution of citric acid, and is therefore on 

 equal terms of " availability " with the 

 phosphate of basic slag. 



The acid character of superphosphate 

 can also be neutralized by mixing this sub- 

 stance with basic slag, and experiments have 

 shown that such a mixture gives excellent 

 results. It may be adopted with advantage 



