MANURES 49 



Further, in valuing manures it is only the 

 '* available " percentage guaranteed in the 

 analysis that should be taken into account. 

 This particularly applies to phosphatic manures, 

 where the analysis is made to look of greater 

 value than it really is by the inclusion of the 

 insoluble phosphates. In the case of slag the 

 available phosphates are described as '* citric- 

 soluble " and in the case of superphosphate as 

 ''water-soluble." It is in buying compound 

 manures that the greatest risk is run of buying 

 unavailable plant-food, as the makers of these 

 manures not uncommonly employ substances 

 that have good percentages of, say, nitrogen but 

 in a very unavailable form. 



Liming requires separate notice, as it is 

 usually done apart from the general scheme of 

 manuring. Lime is not applied to soils merely 

 as a manure, but also to help to render other 

 plant-foods more available, to remove sourness 

 and thereby sweeten the soil, to render clay 

 land more amenable to cultivation, to kill insects 

 and to check fungoid diseases of plants. The 

 commonest forms in which lime is now applied 

 to land is as ground lime (usually ground quick- 

 lime), slaked lime (quicklime acted on by water), 



