326 
JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. 
t October 15,18P1. 
repotting them at this season of the year. It is always somewhat 
risky, even with plants in good health and at the proper season of 
the year, to shake away the whole of the material and supply fresh. 
Where Oattleyas, Lselias, and plants of a similar nature are unsatis¬ 
factory water with care, and atttmpt to ripen thoroughly the small 
but puny growths they may be making. This is the only reliable 
course, and then thoroughly renew the compost just before they 
start into growth during the early spring months. 
Potting Odontoglossums. —Where these have not been re¬ 
potted it may safely be done at once. There can be no question 
that the autumn is the best time for repotting these plants. 
Annual repotting is also recommended. The plants are healthier 
and grow with greater vigour with perfectly fresh than when the 
material about their roots is decomposed. By potting at this 
season there is less risk of injury to their roots than is the case in 
spring. The plants are not long when potted at this season before 
they push out roots in abundance from the base of young growths. 
Temperature for Odontoglossums. —No greater mistake 
can be made in the culture of these plants than to have a low night 
temperature during the winter months. Abundance of moisture 
should be maintained, and the temperature should not be allowed 
to fall below 45° in the morning. The average winter temperature 
should be 50°. If the plants are subjected to a low winter tempera¬ 
ture they become stunted, and will take at least two years to 
recruit them again. It is surprising how quickly the plants go 
back with a low temperature, and how long they need careful treat¬ 
ment before they grow again with vigour.— Orchid Grower. 
MANURING. 
All experience proves that profitable crops cannot be had from any 
soil over a series of years without judicious applications of manure. 
From the soil plants abstract the elements necessary for their health 
and productiveness ; in fact, the soil supplies all the feeding constituents 
required by plants except carbon and nitrogen. But growing crops 
are continually abstracting lime, potash, phosphates, sulphates, and 
nitrogenous substances from the soil, and, as the crops (often the whole 
plants), are taken off the ground the soil slowly but surely loses its 
fertility, weakly plants taking the place of healthy and profitable, 
unless the substances removed in the crops are restored to the soil in 
the shape of manure. 
The constituents of plants are derived from the air and the soil. 
They are classed as organic and inorganic. The organic constituents of 
plants comprise carbon, hydrogen, oxygeD, nitrogen, sulphur, and phos¬ 
phorus. Carbon, forming the woody substances of plants, is obtained 
from the atmosphere in the form of carbon dioxide, CO 2 —that is, one 
atom of earbon connected with two atoms of oxygen. Oxygen and 
nitrogen are partly derived from the air, but these elements are taken 
mainly, and in the case of most plants wholly, from the soil. Certain 
plants, however, possess the power of assimilating atmospheric nitrogen, 
whilst other plants are incapable of extracting this valuable element 
from atmospheric air. Hydrogen, sulphur, and phosphorus are taken 
from the soil. 
The inorganic constituents of plants consist of iron oxide, lime, 
magnesia, potash, silica, soda, phosphoric acid, sulphuric acid, and 
chlorine. All these are obtained from the soil. Plants require adequate 
supplies of organic and inorganic elements to render them healthy and 
fruitful. The organic substances e sential to plant growth are carbonic, 
nitric, phosphoric, and sulphuric acids. Plants also require iron, lime, 
magnesia, potash, silica, and soda. Some plants require large quantities 
of certain elements and small proportions only of other substances. 
This does not imply that the minor constituents of plants need not be 
applied to the soil, or that they are non-essential for the healthy growth 
of plants and a full yield in their crops. Possibly all the inorganic 
elements may be present in the soil in excess of the crop’s requirements, 
but they may exist to no useful purpose, because insoluble, a nd one of 
the objects of manuring is to apply such substances as will render the 
insoluble available as plant foods, instead of allowing them to lie use¬ 
lessly in the soil. Cereals need liberal supplies of nitrogenous manures, 
but the application of nitrogen will only give a Wheat plant falling a 
prey to rust, unless silica in available form is present to strengthen its 
stem and harden its tissues to the extent of maintaining the plant erect 
and resisting attacks of fungus. In fact, it is a great mistake to rely 
exclusively on superphosphates (phosphoric acid) for cereals, or limit 
manuring to potash. True, M. Ville ignores the minor constituents of 
plants altogether, as, for instance, his special manure for Wheat, which 
consists of superphosphate, chloride (muriate) of potash, sulphate of 
ammonia, and gypsum. Indeed, M. Ville states that the only substances 
needed by any soil as manure are mitrogen, potash, lime, and phosphoric 
acid. This manifest reliance on the acid secretion of plants for dissolving 
the insoluble minor constituents of soils and thus rendering them avail¬ 
able as plant food is unwarrantable, anti proved erroneous by the system 
of manuring adopted in this country with the greatest success. This 
consists in supplying the minor constituents of plants to the soil in such 
form as will secure healthy crops and full yields of produce, or the 
manures applied are of such nature and contain elements which, acting 
on the minor constituents, converts them into soluble compounds. 
Kainit, for instance, is admittedly applied to land as a manure for 
Wheat on the sole principle of benefit through its potash, but kainit is a 
very different substance from M. Ville’s potassium chloride, or other 
potash salt. Kainit contains about 24H3 per cent, of pota c sium sulphate, 
and it also contains salt (sodium chloride), and the chloride and sulphate 
of magnesia. Potash effects a better nutrition of cereals, and with nitro¬ 
genous manure counteracts the “burning” of superphosphates (phos¬ 
phoric acid), but potash alone is relaxing, yet kainit, through its soda, 
sets silica free, and the chloride of magnesia acts on the insoluble, so 
that kainit not only affords better nutrition to the Wheat plant, but 
safeguards it against disease, and enables it to maintain itself erect 
under the weight of grain. 
Messrs. Lawes and Gilbert apply the minor constituents under no 
cloak. Their mixture for Wheat not only comprises M. Ville’s super¬ 
phosphate, potash, and ammonia, but soda and magnesia ; therefore 
direct benefit accrues from the application of some of the minor con¬ 
stituents, and others act indirectly on the insoluble minor ingredients, 
and by rendering them soluble they are taken into the plant during its 
period of growth, and thus properly nourished the crop produces a full 
yield. 
Soils may contain a sufficient quantity of the minor constituents for 
any crop’s ultimate requirements, yet not existing in the form of soluble 
compounds during the period of growth, or only in partial and in¬ 
adequate quantities, the plant is ill nourished, oft diseased, and the crop 
does not produce a full yield. A soil may contain potash, lime, and 
phosphoric acid abundantly, yet be more or less barren, because a soil’s 
fertility depends upon the presence within it of all the ash elements of 
plants available as food. It must be remembered that gaseous and 
liquid manures are alone absorbed by the rootlets of plants, and that 
solids are never admitted into the interior of any vegetable. It is 
absolutely essential that the nutrient elements of plants exist in the soil 
in soluble form, and that the constituents of soils occur in such a state 
of combination as give a constant and regular supply of nutrition. 
Mamy crops fail because the soil is not in a condition to support them, 
and this arises in gardens more often through lack of one essential 
ingredient than from a maximum of others. 
A soil may contain a sufficient quantity of potash to yield ten full 
crops of Grapes, and of other elements needed by the Vine 
enough to support twenty crops, yet the excess of the latter will be 
unavailing, for the soil would be exhausted of its potash by the ten 
crops. By adding to such a soil a supply of potash it would again 
become capable of producing a full yield of Grapes, and would go on 
doing so until some other ingredient was used up, when it also would 
have to be added; and so on one substance after another would be 
consumed until the seal became completely infertile. Applying potash 
annually would maintain the soil’s fertility as regards that substance, 
but it would not supply the deficiencies of lime and phosphoric acid, for 
the fertility of the soil depends chemically (1) upon the presence in it 
of all the ash-elements of plants and of nitrates in proper quantity ; 
and (2) on their occurrence there in such states of combination as give a 
constant and regular supply. Therefore it is necessary to add at inter¬ 
vals a quantity of the elements of plant food equal to that which the 
crop removes. This is patent to all scientific and practical cultivators, 
and is the foundation of the use of manirres. Soil exhaustion can only 
be prevented by judicious manuring, and an increase of crop secured by 
giving the soil a larger quantity of the elements of plant-food than is 
needed to replace what has been removed in the crop. Thus soil by 
manuring is made to yield a larger crop than it did in its normal con¬ 
dition. A soil to yield profitable crops must contain all the nutritive 
elements of plants in due proportion and essential form. It cannot 
remain fertile unless the ingredients removed with every crop are again 
added by manure, and from the inexhaustible store of the atmosphere. 
Rotation of crops, although useful, is not sufficient to keep the soil in 
a fertile condition. Alternating on the same soil deep-feeding plants 
and shallow feeders, or following those crops that require phosphates 
with those needing nitrogenous manures, are not alone capable of main¬ 
taining the fertility of any soil. Crops that require a large amount of 
potash should be followed by those requiring only a small amount. One 
crop takes the potash out of the soil, and by the other a certain amount 
of potash comes into the soil. Brassicas, for instance, extract a large 
amount of potash from the soil ; economy prompts following them with 
a crop that requires a small amount only of potash. Indeed, it is easy 
to show by agricultural chemistry that some plants enrich the soil— 
actually manure it for a succeeding crop. A good Clover crop removes 
from the soil when made into hay twice the ash elements and nitrogen 
that are contained in a good Wheat crop, yet the Clover crop may be 
obtained from a soil that will only produce the Wheat crop when aided 
by manure ; indeed, the Clover crop will not only grow on the unaided 
soil, but enrich it so that it can support a subsequent Wheat crop. The 
fertilising effects of Clover are due to its assimilating nitrogen much 
more rapidly and in larger quantity than the Wheat plant. It flourishes 
on a small supply of nitrogen, and gives a full yield where Wheat would 
only make half a crop ; besides this, the Clover leaves in the soil where 
it has grown more nitrogen in its roots than an entire Wheat crop 
contains. On the other hand, Clover adds nothing to the soil in the way 
of ash elements, but it transmutes the insoluble substances into soluble, 
and collects largely by the deep penetrating roots, bringing up plant 
nutrition, and when its roots decay the stores of food remain where a 
succeeding shallow rooting crop can utilise them, whilst the roots can 
follow those of the decayed Clover, and ate better able to withstand 
drought. This enriching process has its limit, for land kept in 
Clover gets Clover-sick, which is considered due to the exhaustion of the 
