270 



CULINARY OR KITCHEN GARDEN. 



till it is perfectly softened and diffused through 

 it, and if, after shaking the heavy parts, it be 

 allowed to settle for a few minutes, the sand 

 will subside, while the clay — which is in finer 

 particles, and less heavy — will still remain float- 

 ing. If the water and fine floating clay be now 

 poured into another vessel, and be allowed to 

 stand till the water has become clear, the sandy 

 part of the soil will be found on the bottom of 

 the first vessel, and the clayey part on that of 

 the second, and they may be dried and weighed 

 separately. If 100 parts of dry soil, not peaty 

 or unusually rich in vegetable matter, leave no 

 more than 10 of clay when treated in this man- 

 ner, it is called a sandy soil ; if from 10 to 40, 

 a sandy loam ; if from 40 to 70, a loamy soil; if 

 from 70 to 85, a clay loam ; from 85 to 95, a 

 strong clay soil ; and when no sand is separated 

 at all by this process, it is a pure agricultural 

 clay." Such a soil is not of very frequent occur- 

 rence ; and were it even so, it would be one of 

 the worst for garden purposes. 



" If a soil contain more than 6 per cent of car- 

 bonate of lime, it is called a marl ; if more than 

 20 per cent, it is a calcareous soil. Peaty soils, of 

 course, are those in which the vegetable matter 

 predominates very much. The quantity of ve- 

 getable or other organic matter is determined 

 by drying the soil well upon paper in an oven, 

 until it ceases to lose weight — taking care that 

 the heat is not so great as to char the paper — 

 and then burning in the open air a weighed 

 quantity of the dried soil : the loss by burning 

 is nearly all organic matter. In stiff clays this 

 loss vrill include also a portion of water, which 

 is not wholly driven off from such soils by dry- 

 ing upon paper in the way described. To esti- 

 mate the lime, a quantity of the soil should be 

 heated in the air till the organic matter is burned 

 away. A weighed portion (200 or 300 grains) 

 should then be diffused through half a pint of 

 cold water, mixed with half a wine-glassful of 

 spirit of salt (muriatic acid), and allowed to 

 stand for a few hours, with occasional stirring. 

 When minute bubbles of gas cease to rise from 

 the soil, the water is poured off, the soil dried, 

 heated to redness as before, and weighed : the 

 loss is nearly all lime."- — Johnston's Agricuitv/ral 

 Chemistry and Geology, pp. 81, 86. 



§ 2. — DETERMINATION OF THEIR 

 NATURE, ETC. 



This is only to be arrived at, with any degree 

 of certainty, by botanical, chemical, or mechan- 

 ical tests — that is, by observing the plants that 

 grow on them ; by chemical analysis ; and by 

 their roughness, smoothness, taste, smell, or 

 fracture. 



For almost all practical purposes the former 

 will be found a safe guide, but for strictly scien- 

 tific determination a chemical analysis is requi- 

 site, while many who are ignorant of both botan- 

 ical and chemical science arrive at pretty cor- 

 rect conclusions by the last of these. The 

 qualities of a soil may be determined with con- 

 siderable accuracy, by a good botanist, from the 



plants which grow upon it, so far as the actual 

 state of the soil has reference to culture ; they 

 do not, however, always indicate the improve- 

 ment of which it is susceptible, although they 

 do so to a very considerable extent. The 2'«s- 

 silago farfara, or common colt's-foot, is as cer- 

 tain an inhabitant of the blue clay as its exist- 

 ence. It has appeared in the clay brought from 

 the bottom of the London basin when boring 

 for water, and exposed to the air, in places where 

 it existed not before ; and the accidental deposit 

 of a single cartload of blue clay upon a barren 

 sandy waste has been soon followed by the 

 appearance of this plant. The Salicornia her- 

 bacea is only found in saline soils ; the Vacci- 

 nium uliginosum in peaty ones ; the Rumex 

 acetosa in ferruginous ; the Arenaria rubra in 

 sandy ; and the Caltha palmtris in marshy 

 soils. Marshy soils are indicated with consider- 

 able certainty by the plants which grow in them, 

 and the same may be said of very dry soils; but 

 the earths of fertile soils cannot be inferred with 

 BO much certainty, as cultivation, manures, and 

 circumstances have so much changed their pri- 

 mitive character. Chemical analysis is not al- 

 ways to be depended upon either, for testing 

 the soil of a large field for example, as there 

 may be a very considerable difference in various 

 parts of it ; so that, in fact, the result of the 

 analysis is that of the identical spot from which 

 the specimen was taken, and may be very dif- 

 ferent from that of other parts — nay, probably 

 from the greater part of the whole field. Loudon 

 thought that " by far the greater number of 

 plants only indicate the state of a soil relatively 

 to water and organic matter. In short," he ob- 

 serves, " nature may be said to have only three 

 kinds of soil relatively to plants — the dry, the 

 moist, and the fertile." " Such a mode of esti- 

 mating the comparative properties of soils," 

 says Mr Stephens, "might be correct enough 

 were their products constant ; but when these 

 change with the circumstances in which the soil 

 is placed, the test scarcely admits of general 

 application." The very circumstance of chang- 

 ing the condition of soils, whether by adding to 

 or diminishing their natural constituent parts, 

 as by manuring, burning, or draining, no doubt 

 has the effect of causing the disappearance «f 

 many plants and the appearance of others ; but 

 these latter indicate, by their presence, the 

 change produced, and form a new series of tests 

 by which the soil, in its improved state, is to be 

 again recognised. A copious application of lime 

 will produce plants affecting a calcareous soil, 

 their appearance indicating the addition of a 

 new matter that did not previously exist in it. 

 Draining produces similar results — namely, 

 the disappearance of bog or aquatic plants, 

 and the vegetation of moderately dry soils 

 appearing. High cultivation is productive of a 

 still greater change in vegetable products; for 

 with the manure the seeds of plants are brought 

 in, the produce of more fertile soils — and even 

 with the crops sown — the seeds of plants not 

 even indigenous to our country, although now 

 erroneously considered as such, will be intro- 

 duced. The Chrysantltemum segetum may be 

 offered as an example. Nothing but a complete 



