68 Calcareous Earths highly beneficial. 



This farm has one very great advantage, that 

 of possessing shell marl : a sufficient dressing of 

 this valuable substratum will last for many 

 years. 



Beside the mechanical powers which are ex- 

 erted by calcareous earths in rendering adhe- 

 sive soils less tenacious, their chemical effects 

 on arable lands are of still greater importance ; 

 for as it is found that the stalks of cabbages, 

 and of culmiferous plants, contain on analysis 

 about two per cent, of this earth, a due supply 

 to soils which do not contain it is absolutely 

 necessary ; for though corn will vegetate luxu- 

 riantly in such soils, and produce an ear or 

 pannicle, it will be found deficient in farina- 

 ceous matter at harvest, yielding nothing but 

 chaff or husks. This is practically known to 

 be the case on the sands of Suffolk, particularly 

 in that wide plain lying between Woodbridge 

 and Orford, where, in most parts of it, are 

 found deep beds of what is there provincially 

 called crag, a congeries of marine shells and 

 exuviae similar to the shell marl of Scotland j 

 excepting that the particles of crag are all as it 

 were case-hardened with the oxide of iron, oc- 

 casioned perhaps by the percolation of the rains, 

 through the ferruginous sands by which these 

 beds are covered. On converting those parts 



