153 
OF GARDENING AS A SCIENCE. 
NO. YII. 
Having at page 131 adduced the authority of Liebig, to show that the humus 
of the soil is not taken up by the roots of plants as nutriment, and suggested to 
the gardener some of the means and experiments by which he may bring the ac- 
curacy of the theory to the test, we propose to dismiss the subject, and, at the same 
time, to lay aside, and altogether repudiate the term humus as applied to the 
garden, leaving the agriculturist to retain it or not at his pleasure. It matters 
little what is said or thought of a subject which the mind cannot understand ; and 
as the horticulturist avails himself of substances little used on the farm, we will 
confine our remarks to them exclusively. 
What, then, is manure, and how does it operate on the produce of the garden ? 
The questions are knotty and complicated, and they apply in a two-fold direction. 
Every one versed in general horticulture must be perfectly aware that the same 
soil, the same enrichment, (or " dress," of whatever kind it be,) will operate very 
differently upon plants in the open ground, and when confined in pots. Take, for 
instance, that staple of the garden, virgin loam ; and at this point we cannot do 
our subject more justice, or afford the reader more satisfactory instruction, than 
by referring to the evidence of the esteemed veteran, Mr. James Main. 
" Newly-reclaimed lands, whether from old pasture, fallen woods, or commons, 
or fresh loam dug from pits, are all, for a few years, exceedingly productive without 
assistance from manure, or other treatment, save diggiug or ploughing. This 
virtue of maiden soil, whatever it may be, is at last dissipated by repeated crop- 
ping ; and then the land must be refreshed with a dressing of some kind of manure, 
I have never read or heard of any trial having been made by chemists to analyze 
maiden earth, with a view of ascertaining what that particular quality is which 
proves so exciting and beneficial to vegetation. Its effects are well known to all 
cultivators. Trenching and trench-ploughing are the ordinary means for gaining 
upon the surface an additional stratum of virgin earth ; and the good effects which 
follow sooner or later are sometimes attributed to the true cause, namely, the ad- 
dition of new, untried earth, though by others it is said to be owing to the increased 
depth of the staple." Mr. Main argues very justly that the new stratum must be 
the exciting agent, and adduces agricultural data to elucidate his argument : — he 
then urges the question, " What is that property of maiden earth, which when 
aerated proves so exciting and nutritive to the roots of plants ? It cannot be humus, 
that is, decayed vegetable matter, unless very ancient indeed, and deposited 
contemporaneously with the chalk formations ; for I have found it reposing on 
chalk in considerable masses which seemed to have felt no disturbance since the 
Deluge, and in situations where no enriching fluids could be received and yet, 
VOL. VIII. — NO. XCI. X 
