Agricultural Chemistry. 
475 
the action of the several individual constituents of manure, witli 
that of their several combinations, upon each of the different 
crops, and then again crop with crop, we cannot fail to see, that the 
general result is entirely' inconsistent with that which the collective 
analysis either of the crops or of their ashes would have led us to, 
had this alone been our guide. Finally, in prominent outline, 
the result is seen to be, that for the production of increased 
growth nitrogenous manures had the most characteristic effect upon 
the cereals ; potass on the leguminous crops ; and phosphates on 
turnips. 
There is another very important point connected with manuring, 
in relation to which we must here adduce some experimental 
evidence, and a few observations. The subject, however, is one 
which, both from its extent and importance, demands that a 
separate paper should be devoted to its elucidation ; we therefore 
the less regret the very cursory manner in which we are now 
obliged to notice it. 
The point to which we refer, is the constantly observed fact 
throughout our experiments, that, although an increased produc- 
tion of the cereal grains (the main saleable produce, and, as it 
were, the final product to which all farming operations tend) is 
only attainable in agriculturally adequate amount, by the accumu- 
lation of available nitrogen loitJiin the soil itself; — yet, in no case 
have we recovered in the increase of crop obtained, as much 
nitrogen as was supplied to the soil in manure. Now, if it be 
proved, that increase of the cereal grains in agricultural quantity, 
is essentially connected with the supply to the soil of much more 
nitrogen than is recoverable in the increased produce obtained, 
it will be obvious, that we have here a fact, which must funda- 
mentally affect the views we entertain as to the principles in- 
volved, not only in direct manuring, but in those other main 
features of agricultural practice, which are had recourse to with 
the same result. 
I - In relation to this subject, we have in our various papers, pro- 
minently called attention to several of the main facts which our 
experiments have brought to light. Thus, we have shown that, 
after supplying to the soil twice or thrice as much niti'ogen as 
was obtained in the increase yielded, there was in the succeeding 
year, either no increase whatever due to the nitrogen not recovered 
in the year of its application, or that such increase in the second 
year, if any, was not only extremely small, but that it occurred 
only when the application of the previous year, had been obviously 
very excessive in relation to the climatic or other circumstances of 
growth of the particular season. Vi/e have also called especial 
attention to the fact, that the increase produced by a given 
amount of nitiogenous supply is very variable, according to the 
