April 2, 1898. 
THE GARDENING WORLD. 
485 
NEW DOUBLE VIOLET, 
MRS, J. J. ASTOR. 
This beautiful Violet, of a deep rosy-heliotrope is 
meeting with a most, cordial reception, and as the 
stock is getting very limited, and we have already 
many orders booked for April and May, we beg all 
intending purchasers will please apply at once to 
prevent disappointment. 
The Managers, Hoed Gardens, Tolnes. 
HARDY GLIMBERS. 
FINE COLLECTION. 
FOR PILLARS, ARCHES, WALLS, 
PERGOLAS, TREES, &c. 
GEO. BUNYARD & CO. 
Beg to say their List of the above may now 
be had free, from 
THE ROYAL NURSERIES, MAIDSTONE. 
FORBES’ , m 
CATALOGUE 1000. 
(Over 150 Pages. Nearly. 150 Illustrations.) 
of Florists’ Flowers and Hardy Border Plants 
is got up regardless of trouble or expense, with the result that 
it is by unanimous consent pronounced the most comprehen¬ 
sive, most aocurate, most reliable, most complete aud best 
extant. 
It gives full and accurate descriptions of everything in the 
way of Florists' Flowers, also colour, height, time of 
flowering, and price of ail the best Hardy Border Plants, 
together with then English or Common Name9, and a mass of 
other Valuable Information that cannot be had else¬ 
where. 
It is In fact a veritable reference-book, invaluable to all 
growers of these plants, and should be in the hands of all 
intending purchasers. Free on application. 
JOHN FORBES, 
ESTABLISHED 1870. 
Nurseryman, Hawick, Scotland. 
" Gardening Is the purest of human pleasures, and the greates 
refreshment to the spirit of man."— Bacon. 
Edited by J. FRASER, F.L.S. 
SATURDAY , APRIL 2nd, 1898. 
NEXT WEEK’S ENGAGEMENTS. 
Wednesday, April 6th.—Royal Caledonian Society’s Show 
in the Waverley Market, Edinburgh (j days). 
Horticultural Soils. —Each succeeding 
^ year sees greater interest taken in the 
questions of soils and manures. The 
latter, of course, are merely intended to 
supplement, artificially, the deficiencies of 
the former, whether natural or induced 
by the removal of the crops which grow 
upon them. The question of horticultural 
soils was taken up at the meeting of the 
Royal Horticultural Society on the 22nd 
ult., by Mr. J. J. Willis from the famous 
laboratory of Sir John Bennet Lawes, 
Bart., Rothamsted, Herts. Mr. Willis 
commenced his lecture by stating that the 
fertility of soils for horticultural purposes 
depended upon the rocks from which they 
were originally derived by disintegration. 
This would apply to the mineral ingredients 
of plant food, and the nature and relative 
quantity of the materials in which the 
valuable elements were primarily locked up. 
The finer the rocks are broken up the more 
plant food they are able to supply ; but 
at the same time these soils must be well 
drained and contain sufficient granular 
matter to render them sufficiently porous 
for the free admission of water and air, so 
that the excess of the former may pass 
freely away, and the latter gain ready access 
to the roots of plants. During heavy rains 
a soil gets its store of water replenished, 
but it depends entirely upon the character 
of a soil as to its holding capacity for water 
and its capability of bringing any given crop 
to maturity by furnishing the supply for 
the immediate necessities of the plants. 
Porosity also allows of the slow ascent of 
water from the lower reaches of the subsoil 
by the process known as capillarity, and 
this, too, at a time when sandy, gravelly, 
or impermeable clay soils may be suffering 
for want of water at and near the surface 
in times of severe and prolonged drought. 
The temperature of a soil is very largely 
dependent upon its porosity, and at no time 
is this more evident than in spring, just 
when the sun is beginning to warm up the 
earth after the departure of winter. Upon 
the nature of a soil depends, also, its capa¬ 
bility of absorbing and storing up of the heat 
of the sun. All these facts are of primary 
importance to the cultivator, because rhe 
earth, as a laboratory for a complicated 
series of chemical changes for the prepara¬ 
tion of plant food, can only accomplish its 
task properly in the presence of a sufficiency 
of moisture, air, temperature, and the 
elements necessary for plant life. They 
were dealt with by Mr. Willis in his own 
particular way as a student and conductor 
of experiments. 
One of the essential ingredients of a fer¬ 
tile soil is humus, consisting of decaying 
vegetable and animal remains, the former 
being the more important of the two. The 
lecturer went on to describe how a soil, 
originally poor in humus, may and does 
come to contain sufficient for the support 
of the higher plants and cultivated crops. 
Very poor or thin soils are capable of sup¬ 
porting only the lower types of vegetation, 
but as these decay and add their quota of 
humus to the originally barren ground, the 
latter becomes proportionally enriched, and 
capable of supporting a higher vegetation. 
Virgin soils, that is, those which have 
never previously been placed under crops 
by man, owe their fertility to the accumu¬ 
lation of decaying and living vegetable 
matter, the latter being added to the former 
by the breaking up of the soil by settlers 
or pioneer cultivators. A soil that is rich 
in humus contains all the elements of plant 
food, including nitrogen, the most important 
and valuable of all. This nitrogen, being 
practically locked up in the humus, is 
gradually released on the decay of the latter, 
and otherwise made available for absorption 
by living plants. The permanent fertility 
of a soil is largely dependent upon its 
capability of retaining plant foods. The 
peaty and fibrous soils and decaying leaves, 
so largely utilised by horticulturists, owe 
their fertility to the fibre and other organic 
matter which they contain, and with 
which nitrogen is always associated. As 
this important element is liberated, it 
undergoes the process known as nitrifica¬ 
tion, after which it is capable of absorption 
and assimilation by living and growing 
plants. In proportion to the amount of 
nitrates and ammonia contained in the soil 
of a garden, so will it be fertile. The 
operations of tillage are directly conducive 
to the activity of the microbes which are 
the nitrifying agents, and gardeners cannot 
be too well acquainted with this fact. The 
stirring of the surface of soil under crop 
keeps down weeds and aerates the soil, but 
it does more in stimulating those lowly but 
all important helping organisms, which are 
present in all soils in proportion to their 
fertility, and whether under cultivation or 
otherwise. Potting soils owe their fertility 
to the quantity of fibre they contain; and 
the rapidity of the liberation of plant food 
is dependent upon the porosity of the 
materials employed. Temperature bears 
strongly upon the process of nitrification in 
the soil, so that vegetables in the open 
garden in early spring have a difficulty in 
procuring the requisite amount of nitrogen. 
Here the cultivator will find it to his 
advantage in coming to their aid with 
some readily available nitrogen in the form 
of nitrate of soda, sulphate of ammonia, 
guano, fowls’ dung, or something of that 
nature. The question of soil nitrogen is 
always one of the burning topics of the 
cultivator ; hence it is in no way surprising 
that Mr. Willis dealt with it rather fully. 
The material known as Jadoo was passed 
in review, because, though not a soil, it 
had been recommended as a substitute for 
it in potting and other garden operations. 
The body or matrix of it consists of peat 
moss, with which phosphoric acid, potash, 
gypsum, bone meal, soot, and other ingre¬ 
dients had been brought together, forming 
a handy or convenient concentration of 
plant food. A most important subject for 
horticulturists to consider is the amount of 
immediately available plant food a soil may 
contain, not merely the total quantity which 
is locked up in it, and which plants are 
unable to appropriate. The growth of a 
plant is absolutely dependent upon the 
whole of the elements of its food being 
present in an available condition, and is 
regulated by that one which is to hand in 
the smallest quantity. It is the duty of the 
cultivator to ascertain which element is 
deficient in any given soil, and to supply it. 
