62 



manures had, by the seventh year of the Rothamsted experi- 

 ments, so strengthened and encouraged the growth of the 

 grasses that the clovers and other leguminous plants had 

 practically disappeared. At the same time, a change of 

 character took place in the plants which were present ; a 

 large proportion of leaf, and comparatively few stems and 

 seeds, being produced. The plants were also late in coming 

 to maturity, apparently later with ammonia salts than on 

 the plots manured with nitrate of soda. 



The following table* shows the principal grasses found 

 on plots variously manured in the seventh season of experi- 

 ment, and the weight of each per cent, in the hay crop of 

 that year : 



TABLE XLIII. 



The increase of the grasses and diminution of clover and 

 other leguminous plants, by the use of nitrogenous manures 

 is very remarkable ; and almost equally so is the difference 

 in effect of ammonia salts and nitrate of soda on individual 

 species. Thus, ammonia salts had greater effect than nitrate 

 of soda in encouraging the downy and yellow oat grasses, 

 common bent grass, and to a lesser extent Yorkshire fog, 

 and the fescues ; while nitrate increased the meadow grasses, 

 cocksfoot, and soft brome grass more than ammonia salts. 

 Similar results were obtained in the Highland and Agri- 



Journal of th2 Royal Agricultural Society of England," Vol. XXIV. 



