192 Causes of Fertility or Barrenness of Soils. 
too much confidence in the correctness of these views till con- 
firmed by further experiments ; though the character of the inves- 
tigator for scrupulous care and unwearied perseverance is almost 
a guarantee for their truthfulness. 
We have now to consider how far the general results of 
analysis, hitherto made, have benefited the practical farmer. 
Certain soils having been found peculiarly adapted to the growth 
of some plants and unsuitable for others, analysis ought to 
point out the reason for these peculiarities, and to a certain 
extent it has done so. But inasmuch as fertility or barrenness 
depends upon the state of combination in which the ingredients 
exist, quite as much as upon the actual existence of the various 
salts, and as analysis hitherto has generally been confined to 
pointing out this latter fact only, we ought not to feel surprised 
that chemical returns have often failed to bear out practical facts, 
i^gain Ave should bear in mind, that although we may in the 
laboratory prove the existence of the elements of fertility, and 
demonstrate their mode of action, yet these facts may be falsified 
in the soil, owing to the presence of other forces of which 
chemistry cannot take account. Professor Way has shown that a 
crop of wheat takes a very small quantity of mineral matter from 
a soil, and that many soils contain abundant supplies for a number 
of crops, yet in practice we can never take more than one crop in 
succession without injuring the land and weakening the produce. 
It is found that those very substances which analysis shows 
already existing in abundance, if added to the soil, produce good 
results. The reason for this discrepancy is doubtless owing to 
the particular state of combination as affecting the solubility or 
insolubility, and the fact that the roots of the crops come into 
connection with only a portion of the fertilising ingredients. 
The chief value of analysis hitherto has consisted in pointing 
out those substances required as food for particular crops, their 
presence in or absence from the soil, and the cheapest form and 
best method of application when deficient ; also in determining 
the relative value of the various manuring substances so con- 
stantly offered to the practical man, in discovering valuable 
manures in the refuse of manufactures which would otherwise 
be wasted, and in the discovery of fossil or earthy manures. Con- 
sidering, therefore, that the science of agricultural chemistry is 
still in its infancy, the opinion that it has hitherto conferred no 
benefit upon agriculture is most unjust, and can only proceed 
from ignorance. We are already indebted to it for a general 
enlightenment as to the principles of vegetable life ; and though at 
present it may not have produced very startling results, still it has 
opened up so many new views, that every man of sense will feel 
grateful for its assistance, and look hopefully forward to the future. 
