50 ON THE USE OF LIME, MARL, AND SHELL-SAND. 



of this soil is interesting, inasmuch as it shows that shell- 

 sand may remain for a long time in the soil, and that therefore 

 good dressings with shell-sand need not be repeated at short 

 intervals. 



The last-mentioned soil is from a pasture meadow which 50 

 years ago obtained a prize as an irrigated meadow. The quan- 

 tity of lime in this soil, taken at a depth of 5 inches from the 

 surface, is small. Probably the surface-soil contains more. 



These instances, referring to the use of shell-sand in Cornwall, 

 I think are instructive. They explain why in some cases no 

 effect whatever is produced by the use of shell-sand, whilst in 

 others even a moderate dressing benefits the crop to which it is 

 applied; and why sometimes shell-sand only produces a good 

 result when it is used in very large quantities, in which case it 

 acts mechanically, and not chemically, upon the soil. In short, 

 the same principles which regulate the application of lime to 

 the soil ought also to guide the farmer in using shell-sand. 

 How far practical men act upon principle it is not for me to 

 decide, but this is quite certain, that instances in which much 

 money is periodically wasted in the purchase and application of 

 lime, marl, or shell-sand, are far more numerous than is generally 

 believed. 



LONDON : PRINTED BY WILLIAM CLOWES AND SONS, STAMFORD STREET, 

 1 -"" ANDCHAKING CROSS 



