214 



GARDENING AS A SCIENCE. 



ed vegetable matter, unless very ancient 

 indeed, and deposited contemporaneously 

 with the chalk formations ; for I have found 

 it reposing un chalk in considerable masses, 

 which seemed to have felt no disturbance 

 since the deluge, and in situations where 

 no enriching fluid could be received, and 

 yet for the sustentation of plants, whether 

 native or exotic, it is invaluable. It would 

 be well, if by chemical analysis, any light 

 could be thrown on the matter. Perhaps 

 it may be some simple body, which can be ar- 

 tificially collected, and applied with less 

 trouble and equal effect, as more ponderous 

 materials." 



If any of our readers can retrace the as- 

 tonishing effects of a loam raised by the 

 spade in trenching from a depth of nearly 

 two feet, and which had evidently lain undis- 

 turbed for centuries, upon a crop of any of 

 the cabbage tribe, he will be satisfied with 

 the truth of Mr. Main's remarks. 



On such a loam, yellow or brown-orange 

 in colour, void of any traceable fibre, and 

 to a demonstration free from a particle of 

 any substance that could bear the name of 

 manure, potatoes, cabbages, broccoli, and 

 the like, will thrive with a rapidity, verdure 

 and luxuriance, that nothing can excel. 

 What then, we inquire, chemically, has 

 been, and is the exciting agent ? Such a 

 loam is composed chiefly of insoluble sand, 

 of perhaps one-fourth of alumine, or the 

 matter of pure clay, of oxide of iron, (the 

 colouring material,) and generally of a 

 small percentage of chalk (carbonate of 

 lime.) Now any or all of these, however 

 varying in their proportions, are little solu- 

 ble in water ; but the loam so constituted, 

 if Liebig's authority be proof, invariably 

 contains a proportion of vegetable alkali, 

 potassa, of which substance, wherever it be 

 found in the vegetable organization, it is the 

 sole source and parent. Here then, Mr. 



Main's most valuable suggestion is realised; 

 for a body, though not absolutely simple, a 

 chemical agent is discovered, which being 

 extremely soluble, is most energetic and 

 potential in its effects upon the vegetable 

 fluids. We are, therefore, justified in con- 

 cluding that to potassa may be ascribed 

 those luxuriant results which are the sub- 

 ject of inquiry. 



But such a loam, however invaluable to 

 vegetable culture, producing that flavor 

 and purity which can never be obtained 

 from manure in any form, will not avail in 

 pot culture ; it is altogether too binding and 

 intractable. The principle, nevertheless, 

 remains in full force, therefore the judicious 

 gardener has recourse to the turf taken off 

 the purest loam of a common or grass pas- 

 ture ; this he lays up in mass, turns, incor- 

 porates, and finally uses with its fibrous re- 

 mains. Hence he obtains the best soil in 

 a form and temperament that will give 

 freedom to the progress of the roots, and 

 yet has not lost one particle of those salts 

 which play so important a part in the eco- 

 nomy of vegetation. 



But does his soil become paler during a 

 course of culture ? Does it in any way pre- 

 sent signs of impoverishment ? Certainly 

 not ; it acquires depth of tint, it gains humiis, 

 and, after a time, the colour is darkened by 

 several shades, proving that carbon has been 

 deposited — not abstracted. Yet new soil is 

 soon required ; and again a prudent addi- 

 tion of fresh turf, and frequently assisted 

 by the whitest sand, will renew the energy 

 of vegetation, and, simultaneously, all the 

 corresponding phenomena. We have now, 

 though conscious of much ignorance of those 

 wondrous causes which are ever varying 

 their " ceaseless change," presented our 

 readers with matter for deep reflection, and, 

 we dare hope, for profitable inquiry and ex- 

 periment. 



