OF

THE CHARACTERS, ABBREVIATIONS, AND INDICATIONS

USED IN BOTANICAL AND FLORICULTURAL NOTICES.

The systematic names of plants are accented as in the Hortus Britannicus. The derivations of the genera are given, and the specific systematic names literally translated, any explanatory words accompanying such translation being printed in Italic. Those names, whether of genera or species, which are commemorative, as Banksia in honour of Sir Joseph Banks, are distinguished by having the subjoined letters in Italic where the rest of the word is in Roman, and in Roman where the rest of the word is in Italic, as Banksia; those which have been applied to plants by the classic writers of antiquity are distinguished by having the initial letter in Italic, as Pyrus, where the rest of the word is in Roman, and in Roman where the rest of the word is in Italic, as Pyrus. All words, generic or specific, of unknown derivation, or aboriginal names, are wholly in Italic or wholly in Roman, according to the letter in which the preceding or following matter may be printed, as Pædèria Lingun Boj., or Pædèria Língun Boj.

THE

GARDENER'S MAGAZINE,

JANUARY, 1843.

ORIGINAL COMMUNICATIONS.

ART. I. On the Theory of Manures. By R. LYMBURN. THE year 1842 has been distinguished by a vast variety of efforts to elucidate the subject of manures; and the many tables published, opinions given, and experiments recorded, have added immensely to the bulk of information from which rules for practice must ultimately be deduced. That much disappointment and many unaccountable results have been produced should not damp our endeavours. The difference of soils has a great effect in producing these: they vary so much in their physical properties, both naturally and artificially, that experiments will require to be often and carefully repeated on different soils, in different seasons, and on a large scale, before they can enable us to form rules for our guidance in practice. A soil naturally porous will produce very opposite results from a sodden stiff soil, and will require very different treatment; if this be neglected, or interfered with by accident, the result may differ very much from expectation. If the season is likely to be wet and cold, the porosity should be encouraged; if dry and warm, the ground should be rolled and compressed; this may be omitted, or the weather may be so very dry that the crop may fail even although this is attended to. If the soil is cold and wet, it may be much improved by cultivation. The skilful cultivator will take advantage of tids of weather, and may make frost, drought, and even wet, assist in pulverising and producing that great requisite, a plentiful supply of moisture to the roots, absorbed from the small pieces of the soil, without an overdose to gorge up the channels of communication between the air and soil. Dry hot manures, strawy and turfy, suit wet soils generally best; and cold wet manures the dry soils. But seasons may reverse this order. In cold wet summers, dry hot manures may do best even in dry soils; while heavy wet land, if worked wet in spring, and a dry summer succeed, may be so coarse in the pieces, so open and porous, as to be benefited most by cold wet manures. It makes no odds how much, and how usually

powerful, may be the manures deposited in the soil, if chemical action is not kept up in the soil, the stomach of the plant, both by the free admission and retention of heat and air. We may have much greater produce from a small quantity of manure under judicious cultivation, than from a great quantity when, by improper cultivation, or by those baffling tids of weather which occur so often to paralyse the efforts of the most skilful, the soil has got out of order. It is difficult to lay down rules stating how much should be ascribed to all these causes; the skill acquired by practice, and great observation and discrimination, with repeated trials on a large scale, will all be needed to elucidate and harmonise conflicting statements. There are particular periods in the stages of existence of plants also, when nourishing weather is more requisite, and the reverse does more harm; as in turnips, carrots, &c., newly above ground, when, if they are stunted and set up, no after nourishing weather will altogether remove the defect; or in grain crops at the time of setting the flower, in potatoes at the time of germination, &c. The different kinds of manure, also, differ very much; some requiring much more chemical action to render them soluble than others.

In experiments, also, conducted on a small scale, on small measured portions of ground and manure, allowance must be given for variations in the state of the soil, at very short distances, in the same field. Where immense level plains or mountainous tracts of great extent occur, the soil is more uniform; but where the land, as in many districts, is undulated through its whole extent, with hill and vale, knoll and hollow, it is found that different portions of a field, within a few yards or even feet of each other, differ much in many respects. One piece, having a stratum of gravel running through it, may be parched and burned up with drought in a dry season; while in a wet season it may retain only its proper quantity. Another piece may be stiff sodden clay, suffering much when the seasons are wet and cold at the time of working, and greatly improved by working dry, and having moist weather afterwards. Another portion may have once been wet and marshy, and accumulated a kind of peaty deposit, which, if drained afterwards, may bear fine crops in ordinary seasons, but will suffer in the extremes both of drought and wet. The field may have had an excellent soil some feet deep deposited on it, but the good soil may have been washed away from some pieces by partial floods, and a stiff obdurate clay exposed: or the reverse may have taken place; the good soil may have been washed from the hills and knolls, and deposited in the hollows. All these varieties occur in the district around this, frequently in the same field. The prevailing rocks are sandstone and greenstone, above

the coal measures; and the varieties produced by the mixture of these are immense.

One end of the seedling beds, along a whole quarter of the garden, may be of a loose friable, though loamy, nature, suiting most seasons well; while the other end of the beds may be found of a stiff retentive nature, which hardly any season is found to suit, yielding scarcely any crop in comparison, though covered with double the quantity both of manure and seed; yet at times, by the agency of frost, with dry digging and pulverising, these same ends may, in some seasons, be nearly equal to the other. Many districts also, from the prevalence of moor land, and the want of plantations to shelter, are much colder than others in the neighbourhood more favourably situated. Some hills slope to the south, and others to the north; some abound in inequalities, while in others the slope is regular. Fields, and pieces of fields, and gardens will also differ much, as to the quantity of organic remains left from previous crops, or deposited from the roots, or accumulated by accident. The mechanical state will also differ much, from portions being dug for the previous crop in wet or in dry weather, from trenching, draining, &c.

When so many causes are at work, which may all at times affect the results of experiments, we must not be discouraged though we do not get exact comparative results from measured portions of soils and manures; and be content, if, from a great variety of experiments carefully observed in all their bearings, on various soils, in various pieces of the same field or garden, and in various seasons and circumstances, the truth should after

all begin to emerge. If these experiments give rise to theoretical opinions for which the reasons seem well grounded, and if these theoretical opinions are confirmed by future practice, a solid basis may be built, by the united aid of science and practice, which neither the one nor the other could, of itself, have so perfectly attained. The subject must be thoroughly investigated in all its bearings; and, however many deceive themselves or succeed in deceiving others, it can only be for a time. Practice will banish false theories and establish the truth, if properly and unprejudicedly observed. We must not be hasty in our conclusions, and must take proper observation of the soils experimented on, the circumstances they are placed in, the nature of the seasons, and how all these bear on one another, and may be calculated to affect or be affected by the substances deposited as manures. When practical men, generally, get so far versed in the elements of science as to enable them to follow out all these subjects in all their bearings, an immense power of observation will be brought into action, and must ultimately be productive of vast benefit.

It has been attempted to simplify the subject, by selecting some one of the constituents of manure as the most essential. Of the four principal and most abundant elements, hydrogen and oxygen being got from the water absorbed, and carbon partly from the air and partly from the soil, and not yet properly decided how much from each, nitrogen has been selected. Being generally found in combination with carbon and other substances needed as food, being necessary in the transformations carrying on in the circulating sap, assisting greatly in all the fermentations of manures, and being always found in greatest quantity in the spongioles of the roots, and in the young shoots and leaves, wherever vitality is most active, it has, though small in amount as a constituent, been found very important. It has not been found, however, that manures always produce results in proportion to the quantity of nitrogen they contain, nor that crops exhaust the fertility of the soil in the ratio of the quantity of nitrogen they take from it. It has been found, also, that great effects have taken place from an augmentation in the usual quantity of the inorganic saline substances of manures; and hence nitrogen, though perhaps the most essential ingredient taken by itself and with regard to its combinations, yet cannot generally be taken as an exact measure of value for the whole.

Dr. Madden, in his Essay published in the Highland Society's Transactions (Quarterly Journal of Agriculture) for June last, takes a more extended view of the subject, and proposes to compare the value of manures by

1st. The quantity of soluble matter present.

2d. The facility with which those portions at first insoluble can be rendered capable of solution by the process of decay. 3d. The quantity of azote (nitrogen) they contain.

4th. The whole quantity of organic matter possessed by them.

5th. The quantity of inorganic matter which each contains, possessing the same constituents as the ashes of the crop to which it is applied.

Bone dust he finds, by analysis, to contain of