238 



SOILS AND MANUKES 



substance is decomposed. The change may be brought 

 about by a natural process of fermentation, or as a 

 result of artificial treatment. Consequently they act best 

 on light open soils moderately well supplied with lime, 

 and some of them are very suitable manures for this 

 class of soil. Even under the most favourable conditions 

 their action is relatively slow, i.e., as compared with the 

 very rapid effects of sulphate of ammonia, etc. They 

 are, however, valuable manures, and when they can be 

 obtained at a reasonable price, are useful for many 

 purposes. With the addition of potassium compounds 

 they form general manures. 



BONES. 



Special interest attaches to the use of bones as manure, 

 both historically and economically. They appear to have 

 been, at first, employed chiefly for pastures as a means 

 of restoring some of the principal ingredients removed 

 from the land by grazing stock. They were afterwards 

 applied to other crops, and soon became extremely 

 popular. It is estimated that something like 100,000 tons 

 of bones are now annually used as manure in this 

 country. About one half of this quantity is collected 

 at home, and the remainder is imported from abroad. 



Imports. The following tables show the quantities 

 of bones for use as manure, imported into the United 

 Kingdom in 1907 from various countries, and the total 

 quantities in each of the last ten years : 



Tons. 



Argentina 17,491 



Total . 46,115 



