478 
Agricultural Chemistry. 
land, in the cereals and leguminous crops respectively, which are ■ 
calculated to give at least a direction to our conclusions, in refer- 
ence to the assimila'.ion of nitrogen in the case of an unmanured 
cereal plot. Thus, the striking fact appears, that under similar 
unmanured or mineral-manured conditions, the produce of nitrogen 
per acre, may be twice and a half or thrice as great in one and 
the same season, with the leguminous, as with the cereal crop. 
This relation, therefore, between the amount of nitrogen assimi- 
lated under given circumstances in the leguminous crop, as com- 
pared with the cereal, is strikingly similar to that which is found, 
between the nitrogen of manure and that in the i//c7 <?os«/ produce 
of the cereal obtained by its use. 
Baron Liebig further alleges against our conclusions, that we 
have no evidence that the unrecovered nitrogen did not remain in 
the soil for tlie use of the future crops ; that we should have • 
employed very much smaller amounts of ammonia-salts, to prove 
that the smaller did not give an equal inciease of produce with 
the larger, as well as to ascertain the minimum amount of ammo- 
nia-salts required to produce a maxinmm effect ; and further, 
that the assumption that 5 lbs. of ammonia is required to produce 
a bushel of increase is no expression of a natural relation between 
manure and crops. We shall examine these several allegations. 
Firstly, then, as to the assertion, that we have no evidence that 
the unrecovered nitrogen of the manure, did not remain in the 
soil for the succeeding crops. Not only had ?fe sufficient evi- 
dence on this point, but Baron Liebig had iiimself, in our own 
recorded results, the proof of it in the degree in which we have our- 
selves maintained it. What we say is, that even when ammonia- 
salts are not used in greater excess than is adapted for a full 
average effect in any given season, still, probably, only from one- 
third to one-half of the nitiogen so supplied, will be recovered in 
the increase obtained in the year of the application ; that this 
unrecovered nitrogen will yield little or no increase in the suc- 
ceeding year ; that if, under these circumstances, ammonia be 
again added, we shall, otlier conditions being equal, again get a 
large increase of produce ; and further, that if more ammonia 
have been employed than is suited to give a fair increase of crop 
on the average of seasons, even then the effect of the residue in 
the succeeding year will be, comparatively speaking, very trifling. 
The registry of facts in Table V. will illustrate tlie above state- 
ments. 
We could multiply instances of this kind illustrating the point 
in question ; but those here given are suffcient to prove tlie fact, — 
that a moderate supply of ammonia-salts to the wheat crop, did 
not leave any efficient residue for tlie succeeding season. And 
such a result, we mnintain, is entirely in accordance with the 
