Coproliths 



is put in the soil it will be lost by drainage if it cannot 

 find a base for fixation, or becomes bicalcic and in- 

 soluble in the water, and the oft-quoted advantage 

 or solubility of superphosphate is reduced to nearly 

 nothing, since it must first have rain (which does not 

 always arrive) to help its dissemination, the dispersal 

 by reason of solubility, by the water in the soil, being 

 reduced to a minimum, and practically limited to 

 two or three inches of the top soil, because of its 

 insolubilisation by the bases. 



On the other hand, bicalcic phosphate is very 

 assimilable by plants, so that reversion ought not 

 to be regarded as an obstacle to its employment. 

 If it were not too dear it could be applied to any 

 acid land where superphosphate cannot be used 

 advantageously, because of the lime in the basic 

 slag. But it must be noted that the value of basic 

 superphosphate does not lie in the total phosphoric 

 acid, but depends very largely on the quality of 

 basic slag employed. 



If the farmer understands the use of basic slag 

 and superphosphate he need not employ basic 

 superphosphate. 



Coproliths. 



Coproliths are impure mineral phosphates, pre- 

 sented in the form of hard nodules, brown or reddish 

 in colour, varying in size from a pigeon's egg to an 

 ostrich's. The name is derived from the Greek, 

 and means " stones of dung." They are fossil 

 excrements attributed to fishes or to saurians 

 that lived in prehistoric times, and are found in 

 many places in England, notably Suffolk and 



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