SOILS— THEIR IMPROVEMENT. 



281 



ried to the end where the operation is to finish. 

 Lay a good dressing of dung on the bottom of 

 the opened trench and dig it deeply in, then 

 fill in with the top spit and shovelling of the 

 next trench, which serve in the same manner, 

 and so on till the whole is finished. By this 

 mode the good soil is kept still on the top, and 

 the subsoil is enriched and loosened at the same 

 time, providing nourishment to the roots, and 

 inducing them to descend in search of it. In 

 time, this improves the soil to a sufficient depth 

 for ordinary purposes, allows the rain to pene- 

 trate dowuwai'd, and prevents the crops from 

 sufiering from drought. The only objection to 

 it is that little change takes place in the soil, 

 the top remaining at the top, and bottom at 

 the bottom. Strong soils are rendered more 

 open by it, the capacity of absorbing moisture 

 is increased, and the surface is rendered 

 drier. 



In trenching, besides the amelioration of the soil 

 by the mechanical operation of loosening, mixing, 

 and turning over, other advantages should be 

 aimed at ; as, for instance, where it is of a strong 

 retentive description, river or any sharp sand, 

 lime-rubbish, the refuse chippings of soft sand- 

 stone incorporated with it, will be found 

 of vast importance. In soils of an opposite 

 character, or such as are denominated light, 

 hot, dry, and hungry, abounding to an extreme 

 in sand, and deficient in vegetable matter, 

 clay, turfy peat, vegetable mould, marl loam, 

 &c., should be added. Indeed, anything that 

 can be procm-ed of a diametrically opposite 

 character to either of these soils, if added, will 

 improve them. Clay, if very strong, may be 

 advantageously laid on the surface in autumn, 

 and when broken down by the winter frosts, 

 will be in excellent condition to incorporate 

 with the soU. Changes thus effected wjll be 

 far more lasting and beneficial in their efiects 

 than aU the manure that can be appUed without 

 them. 



Consolidation is a species of soil-improvement 

 the very opposite to pulverisation. It never- 

 theless sometimes becomes necessary, as in the 

 case of light spongy peat-soil and very light sand. 

 Neither of these, however, are often met with in 

 garden culture. Compression is employed when 

 seed is sown in dry weather upon light soils, 

 and is effected by treading or rolling. Deep- 

 digging and trenching, where the soil admits of 

 it, should not, however, be disregarded, the 

 operation of compression being confined to the 

 sm'face only. 



Alteration of the constituent parts of soils. — 

 This is a species of improvement of vast import- 

 ance, and consists in adding or subtracting those 

 ingredients in which they are deficient or pos- 

 sess in superabundance. This species of im- 

 provement, in the present case, we will consider 

 with reference only to an alteration of its tex- 

 ture, and observe that sandy soils will best be 

 improved by the addition of alumina or clay, 

 and strong clayey soils by an admixture of sand ; 

 and in both cases lime should be added, as no 

 soil can be permanently fertile vdthout alka- 

 line matter. A much smaller quantity of clay 

 applied to even a drifting sand will consolidate it. 



and convert it into a good working loamy soil, 

 than of sand to produce a like effect upon strong 

 clay. Peat or other vegetable matter added to 

 sand will enrich it, by supplying organic or vege- 

 table matter in which the sand is deficient : but 

 although this increases its fertiUty, it adds little 

 to its texture ; it may, therefore, be added as a 

 compound mixed with clay and lime. Light sand, 

 on a subsoil of loam or clay, will be improved by 

 trenching so deep as to bring up a sufficient 

 proportion of the clay to the surface ; and peaty 

 soils will be improved by the addition of sand, as 

 well as of clay and loam. The quantity of one 

 soil to be added to another, so as to render its 

 texture perfect, can only be determined by ex- 

 periment. The following is given as a practical 

 example : " If we take an extreme case, and 

 suppose that any given soil is so sandy as to 

 require the addition of one-sixth its bulk of clay, 

 or so clayed as to require one-sixth of its bulk 

 of sand, then, in the case of a kitchen-garden, 

 when the soil is 3 feet deep, every square foot 

 of the clayey surface will require the addition of 

 half a cubic foot of sand ; and, in the case of a 

 lawn, where the soil is 1 foot in depth, every 

 square foot of sand will require the sixth of a 

 cubic foot of clay. To cover a statute acre with 

 soil to the depth of 1 inch, will require 121 cubic 

 yards. Hence, to add 2 inches to the soU of a 

 garden of 1 acre, exclusive of the space occupied 

 by the walks, would requii-e 242 cubic yards or 

 cartloads. It frequently happens that a sandy 

 or gravelly soil is incumbent on a bed of clay, 

 and the contrary. In either of these cases, the 

 supply of the required soil may be obtained by 

 digging pits, or sometimes even by deep-trench- 

 ing. The earth thus obtained will generally be 

 without organic matter, but that can be supplied 

 afterwards by manui'ing. Whei-e the soil re- 

 quired for the improvement of another soU can 

 be obtained in the state of surface-soil, the effects 

 produced will be the more immediate for the 

 organic matter that such soil contains ; but even 

 when it is obtained from the subsoil, the change 

 in the condition of the soil to which the new 

 soil is applied will soon be rendered obvious, 

 though not so much the first year as it will be 

 in two or three years afterwards, when the amal- 

 gamation of the two soils is more complete. 

 Much of the effect of adding one soil to another 

 will depend on their intimate mixture, and this 

 can be best effected by repeated trenchings or 

 diggings in dry weather, and when both soUs are 

 as nearly as possible in a state of diy powder. 

 This point is of great importance, particularly 

 when the soils mixed together contain a good 

 deal of organic matter, because, if a very inti- 

 mate mixture of both soUs is not effected, they 

 will, from the difference of their specific gravi- 

 ties, in a few years separate into two different 

 sti-ata. There is, indeed, a constant tendency 

 to do this in all soils under culture, and more 

 especially in all such as have been improved by 

 admixture. This takes place in consequence of 

 the softening of the soil by rains, by which the 

 particles are, in a manner, held for a time in 

 suspension, and the heaviest gradually take a 

 lower place than those which are lighter. Hence 

 the necessity of digging or trenching such soils 



