282 



CULINARY OR KITCHEN GARDEN. 



occasionally to the depth to which they have 

 originally been improved." — SvJi. Hort., p. 52. 



Expomre to atmospheric influence. — The action 

 of the atmosphere eCfects important changes on 

 soils. Indeed, as has been already stated, some 

 trace the very origin of soils to atmospheric 

 causes. Some of the advantages soils attain from 

 exposure to the atmosphere have been noticed 

 under the head Pulverisation. The others are 

 eflfected by altering the position of their surface, 

 by throwing it up into narrow ridges, deep-dig- 

 ging, and leaving the surface as rough as pos- 

 sible, frequently stirring it with the hoe, and 

 tearing it up, where the soil is hard or tenar 

 cious, with the pick, or, still better, with Glen- 

 dinning's pick-fork, vide fig. 85. The effects 

 of all these are to render the surface open and 

 pervious to solar heat, frost, and rain, which, 

 acting by expansion, contraction, &o. of its parts, 

 break it down, and render it more fitting for the 

 growth of plants. " The influence of the sun's 

 rays upon any plane are demonstrated to be as 

 their number and perpendicularity to that plane, 

 the effects of the atmosphere being excepted. 

 Hence one advantage of ridging land, providing 

 the ridges run from north to south ; forjOn such 

 surfaces the rays of the morning sun will take 

 effect sooner on the east side, and those of the 

 afternoon will remain longer in operation on the 

 west side ; whilst at mid-day his elevation will 

 compensate, in some degree, for the obliquity 

 of his rays on both sides of the ridge." — Encyc. 

 of Gard., p. 477. Another advantage such an ope- 

 ration on surfaces has is, that the soil wiU dry 

 sooner than if left undisturbed, on account of a 

 freer evaporation going on. The air, upon which 

 so much of the success of cultivation depends, 

 will be admitted more readily to the roots of 

 plants ; and when we consider that they derive 

 so much of their support from that element, the 

 necessity of admitting it into the ground largely 

 will be the more apparent. 



Burning soils, with a view to their improve- 

 ment, is an important matter in preparing land 

 for planting, laying down as lawns, &c., and has 

 of late been strongly recommended for almost 

 all garden purposes. 



The theory of burning soils rests entirely on 

 chemical doctrines, of which Sir H. Davy and 

 others have given clear elucidations. The ad- 

 vantages of burning "are, that it renders the 

 soil less compact, less tenacious, and less reten- 

 tive of moisture ; and when properly applied, 

 may convert a matter which was stiff, damp, 

 and in consequence cold, into one powdery, 

 dry, and warm, and much more proper for a bed 

 for vegetable life." — Encyclopedia of Gardening, 

 p. 477. The chemical change which takes place 

 in soils subjected to the process of torrefaction, 

 is stated by Sir H. Davy to be as follows : 

 " The bases of all common soils are mixtures 

 of the primitive earths and oxide of iron; and 

 these earths have a certain degree of attraction 

 for each other. To regard this attraction in its 

 proper point of view, it is only necessary to 

 consider the composition of any common sUi- 

 cious stone. Felspar, for instance, contains 

 siliciouB, aluminous, and calcareous earths, fixed 

 alkali and oxide of iron, which exist in one com- 



pound, in consequence of their chemical at- 

 traction for each other. Let this stone be 

 ground into impalpable powder, it then be- 

 comes a substance like clay ; if the powder is 

 heated very strongly, it fuses, and in cooling 

 forms a coherent mass similar to the original 

 stone ; the parts separated by mechanical divi- 

 sion adhere again in consequence of chemical at- 

 traction. If the powder be heated less strongly, 

 the particles only superficially combine with 

 each other and form a gritty mass, which, when 

 broken into pieces, has the character of sand. 

 If the power of the powdered felspar to ab- 

 sorb water from the atmosphere before and 

 after the application of the heat is estimated, it 

 is found much less in the latter case. The same 

 effect takes place when the powder of other 

 silicious and aluminous stones is made the sub- 

 ject of experiment ; and two equal portions of 

 basalt ground iuto impalpable powder, of which 

 one-half had been strongly ignited, and the 

 other only exposed to ■■• temperature equal to 

 that of boiling water, gained very different 

 weights in the same time when exposed to air. 

 In four hours the one had gained only two 

 grains, while the other had gained seven grains. 

 When clay or tenacious soils are burnt, the 

 effect is of the same kind ; they are brought 

 nearer to a state analogous to that of sand." 



There is no doubt something startling to the 

 mind of the practical cultivator in the idea of 

 burning soil, not taking, at the same time, into 

 consideration that the process is not recom- 

 mended as applicable to all soils, but only to 

 some ; and these are such as contain a super- 

 abundance of vegetable matter in a dead inert 

 state like most peat soils, and those requiring 

 more powerful agencies than that of mere 

 working with the spade to bring them to a 

 state more useful to plants, such as strong clays 

 and tUly soils. Upon both of these the operas 

 tion of burning has been attended with marked 

 advantage. In connection with horticulture, 

 there is another class of soils that are benefited 

 by such an operation : these[are old garden soils, 

 glutted with organic matter by the yearly ap- 

 plication of manure-dung, the lapse of ages, and 

 at the same time replete with destructive in- 

 sects, in all their various states of transformation 

 from the egg to the perfect state. Such soils 

 are benefited by burning, or perhaps by the less 

 torrefying operation of charring or half- burning, 

 a process highly recommended by many of our 

 most enlightened horticulturists. This we shall 

 now proceed to notice ; but before doing so, 

 we may remark that both burning and charring 

 the soil have been carried to a much greater ex- 

 tent in England than in Scotland, but why, we 

 must leave our readers to speculate. 



Charring is a process for correcting the tena- 

 city of strong soils, accumulating manure, and 

 converting materials, in themselves next to use- 

 less, into excellent fertilisers, such as sawdust, 

 prunings of bushes and hedges, coarse turfy 

 sods, the parings of road-sides, tanners' bark, 

 shavings, and similar vegetable matters. Mr 

 Barnes of Bicton was amongst the first to bring' 

 this material before the notice of the gardening 

 public ; his mode of operation, therefore, may 



