DR. J. H. GILBERT ON CLOVER-SICKNESS. 
89 
been supplied in manure ; but where tliere is partial success both 
have been supplied, but neither of them in amount equal to that 
of their removal in the crops. With regard to mineral consti- 
tuents, the conditions of series 1, resulting in failure, are — a 
considerable excess of supply of both potass and sulphuric acid, 
and a considerably greater excess of both than on either series 2, 
or series 3 ; no essential difference as to phosphoric acid ; a 
greater deficiency of magnesia than in either series 2 or series 3 ; 
and lastly, a considerable loss of lime, whereas on the plots of 
series 2 and 3, very much more lime has been supplied in ma- 
nure than taken off" in the crops. 
It would appear, therefore, that if the failure on series 1, 
compared with series 2 and 3, be due to the greater exhaustion 
of certain constituents, it must be of either carbon, nitrogen, 
magnesia, or lime. On this point it may be mentioned that the 
excess of carbon removed in the crops, over that supplied in the 
manure, has been in no case nearly approaching that which 
may take place with impunity in the case of either wheat or 
barley. On the other hand, the average annual removal of ni- 
trogen has been considerably greater on all the plots of series 1, 
but generally less on those of series 2 and 3, than happens with 
either wheat or barley grown without nitrogenous manure; it 
has, however, been considerably less than in experiments on the 
mixed herbage of grass-land where no nitrogenous manure has 
been employed. 
Again, taking of course the whole period, the exhaustion of 
magnesia has been generally greater, and that of lime consider- 
ably greater, than has occurred in the experiments on the con- 
tinuous growth of wheat or barley. So far, then, as the result 
depends on mere amount, rather than on condition or distribu- 
tion of constituents, it would appear to be connected with a 
deficiency of nitrogen, of magnesia, or of lime, or of more than 
one of them. 
Having regard to the question of the condition and distri- 
bution of the constituents, in 1864 a portion of the land of 
series 1 was trenched 2 feet deep, one third of the manure being 
mixed with the layer from 24 to 16 inches, one third from 16 to 
8 inches, and the remainder from 8 inches upwards. Super- 
phosphate of lime, and salts of potass, soda and magnesia, the 
first two in very large quantity, were used ; and nitrate of soda, 
which is a much more favourable form of application of nitrogen 
