9 
352 
how a soil may be exhausted of some essential material by raising the 
same crop on it year after year, and how even if a rotation is observed 
and none of these substances taken from the soil by the crops are returned 
to it in the shape of manure, it must in the course of time become com¬ 
paratively barren, by being unable to afford certain mineral matters in 
quantities sufficient to enable the plants to grow in a healthy and vigorous 
condition. 
The chemical composition of most farm plants has now been deter¬ 
mined ; various kinds of matter used as manure, have also been analyzed. 
It is therefore possible to ascertain what different plants require and 
what different manures are capable of affording. But before extraneous 
or special manures can be applied with certainty and advantage, we should 
know what the soil contains : whether it is really deficient in some one 
or two mineral matters required by plants. The chemical composition of a 
soil, however, can only be satisfactorily ascertained by an expert analyti¬ 
cal chemist, and as we are not likely to receive any aid from this source 
soon, we shall have to trust to accumulated experience to guide us in this 
inquiry. I hope to see in future volumes of the Transactions of our Society 
the results of experience as to the best and most profitable rotations of 
crops ; whether some soils seem better adapted than others to the growth 
of certain crops, and whether any substance has been used as manure 
other than that made on the farm, and with what results. If a certain 
rotation, or a certain manure had been proved to be advantageous in one 
soil or district, it might prove equally efficient in a like soil in other parts. 
At all events, a simple statement of the results obtained, beneficial or 
otherwise, might lead to further experiment and inquiry which could 
not fail ultimately to add to our store of useful knowledge. Soils are 
originally derived from the disintegration or decay of rocks ; and as rocks 
differ in their composition, providing a soil is derived from the rock im¬ 
mediately below it, on which it rests, or from the rock on a hill above it, 
and is not composed of drifted materials, as frequently happens, the 
composition and physical character of the soil will be influenced by the 
nature of the rock. 
In the first Vol. of the Journal of the Agricultural Society of England,, 
there is an interesting and useful paper on the application of geology to. 
agriculture, which I may refer to in illustration. A gentleman possess- 
i 
