or clay with the sand.
The parks and gardens of Paris, Versailles, and Haarlem are on deep
sands that drift before the wind when left exposed for any length of
time with no crop upon them; and not only do we see the finest of
Potatoes and the most nutritious of herbage produced on these soils, but
good Cauliflowers, Peas, Beans, Onions, fruits, and big trees of sound
timber.

Garden soils usually consist of loam of some kind, the consequence of
long cultivation. Natural loams are the result of the decay and
admixture of various earths, and they are mostly of a mellow texture,
easily worked and highly productive. They are, as a rule, the best of
all soils, and their goodness is in part due to the fact that they
contain a little of everything, with no great predominance of any one
particular earth. Cultivation also produces loam. On a clay land we
find a top crust of clayey loam, and on a lime or chalk land a top crust
of calcareous loam. Where cultivation has been long pursued the staple
is broken and manures are put on, and the roots of plants assist in
disintegration and decomposition. Thus there is accumulation of humus
and a decomposition of the rock proceeding together, and a loam of some
sort is the result. Hence the necessity of caution in respect of deep
trenching, for if we bury the top soil and put in its place a crude
material that has not before seen daylight, we may lose ten years in
profitable cropping, because we must now begin to tame a savage soil
that we have been at great pains to bring up, to cover a stratum of a
good material prepared for us by the combined operations of Nature and
Art during, perhaps, several centuries. But deep and good garden soils
may be safely trenched and freely knocked about, because not only does
the process favour the deep rooting of the plants, but it favours also
that disintegration which is one of the causes of fertility. Every
pebble is capable of imparting to the soil a solution--infinitesimal,
perhaps, but not the less real--of silica, or lime, or potash, or
phosphates, or perhaps of all these; but it must be exposed to light and
air and moisture to enable it to part with a portion of its substance,
and thus it is that mechanical tillage is of the first importance in all
agricultural and horticultural operations.

The principal inorganic or mineral constituents of plants are potash,
soda, lime, iron, phosphorus, sulphur, chlorine, and silica. Clays and
loams are gene