116 AGRICULTURE 



of loss by washing are at a minimum, and 

 where the conditions for nitrification are, as 

 a rule, not wholly satisfactory. On account 

 of its attracting water from the air, the 

 continued use of nitrate of soda in large 

 quantities upon strong clay may result in the 

 soil getting into bad mechanical condition, but 

 this result is unlikely to attend the use of nitrate 

 of soda in ordinary agricultural practice. 



The experiments at Rothamsted and 

 Woburn have shown very conclusively that, 

 to give its best results, sulphate of ammonia 

 must be used on soil containing a fairly high 

 percentage of lime. At both these stations 

 the annual use of ammoniacal salts has 

 frequently resulted in great reduction of 

 fertility ; in fact, at Woburn, the barley and 

 wheat plots getting liberal annual dress- 

 ings of this manure for over thirty-five years 

 have long since become absolutely barren. 

 Chemical examination of the soil has shown 

 that it is markedly acid, and that practically 

 all the lime has been removed from it. This 

 result has been produced by the acid of the 

 ammoniacal manure entering into combination 

 with the lime of the soil, the latter being 

 removed in the form of soluble calcium salts. 

 That this explanation is satisfactory appears 

 to be confirmed by the fact, that when a 



