12 



CASSELL'S POPULAR GARDENING. 



ground-level into a terrace or artificial wide prome- 

 nade with the worthless diggings. And the fertile 

 surfaces have been entombed where we least expect 

 it, and barren earths without either texture or 

 strength substituted for them. 



Testing the Depth and Disposition of 

 Surface Soil. — It is impossible to exaggerate the 

 importance of this precaution. The dangerous leap 

 in the dark of some landscape gardeners and ci^-il 

 engineers, who will begin to level ground without 

 first testing its quality, is about the most reckless 

 and wasteful expenditure of time and money. Small 

 test-holes, about half a yard square, at intervals of 

 ten or more yards apart, will generally furnish suffi- 

 cient information, and guide the proceedings of the 

 leveller. 



It is one of the most mischievous popular errors to 

 suppose that the surface soil, or tilth as it is called, 

 will be found of one uniform depth throughout. As 

 well might the geologist expect the rocts' strata to 

 overlay each other with as much regularity as a 

 pile of books on their sides on a shelf or table, 

 without any tilting whatever. The surface soil, 

 alike in depth and quality, is one of the most variable 

 factors in this world of change. It is no business of 

 the mere leveller to exactly determine its quality, 

 though the more correctly he can read off that at 

 sight, the better for him and the quality of his work. 

 But he can measui-e its depth, and so estimate its 

 mass, as to calculate with approximate exactness 

 how far it will cover the entire area of the garden to 

 a uniform depth. The following formula, which is 

 tolerably correct, furnishes a useful guide in the 

 practical levelling" of gardens : — An inch per acre 

 requires about a hundred cubic yards or tons of 

 earth. Further, a common cart-load is about a ton. 



Even where art has not disturbed the surface soil, 

 it is astonishing how greatly its depth and quality 

 vary in places near to each other. It is difficult to 

 account for these wide variations, whatever theory of 

 its manufacture and deposition be adopted. For its 

 infinite gradations of depth remain almost equally 

 mysterious, whether we attribute its formation to 

 atmospheric influence, or primitive rocks or subsoils, 

 the rise, progress, and decomposition of vegetables, or 

 the direct and active agency of earth-worms. If the 

 latter have formed the mass of surface soU, how came 

 they to be more numerous in one place than another, 

 and that before the surface soil had been deepened ? 



Lea\-ing this, and kindred subjects concerning the" 

 formation and arrangement of surface soil, for special 

 treatment by itself, all that concerns us here is 

 the levelling of soil and subsoil, so as to have the 

 surface or vegetable mould of one uniform depth 

 throughout. 



Level Subsoil and Surface Soil Together. 



— At the same time, so \itaUy important is it that the 

 subsoil should be levelled, that the ad\'ice to level it 

 first of all would be given, were that possible. As 

 that cannot be, the levelling of the two should 

 proceed as nearly abreast as practicable. The surface 

 reveals its own inequalities, but it is only by the use 

 of test-holes that the inequalities of the subsoil can 

 be discovered. It is too often taken for granted that 

 the surface tilth will be found of one uniform depth 

 throughout. There are, however, dips in the suiiace 

 mould as well as in the subsoil and lower strata : 

 and it is most important that the garden modeller or 

 moulder should make himself acquainted with their 

 existence. They will enable him the better to calcu- 

 late on the depth of siu-face soil generally, and how 

 much of the subsoil, or other, will be needed to im- 

 part to the garden the most desirable depth of working 

 soil, or surface mould. Having collected these data, 



rig. 1.— Ground Dug out to Levei Surface Soil and Subsoil 

 together. 



and taken the level by some of the simple processes 

 about to be described, he may then proceed to remove 

 the surface soil bodily from a space of ground three 

 or four feet wide, carting or wheeling it away to the 

 other side of the piece of ground to be levelled. The 

 next operation is to dig out or remove a sufficiency 

 of the soil to allow of eighteen inches, two feet, two 

 and a half, or three feet, for surface earth (see Fig. 1). 

 During this process see that the subsoil is formed of 

 the same shape, with exactly the same incline, as the 

 surface. As soon as this is done, proceed to operate 

 on another sx^aee of three or four feet, of exactly the 

 same area. In moving this one to the opening, as it 

 is technically called, it should be manipulated in such 

 a manner as to thoroughly mix the surface soil, sub- 

 soil, and new earth, if any added ; that the surface 

 mould should be a careful admixture in proper pro- 

 portions of the three or more earths used in it. It is 

 impossible to lay down any strict rules regarding* 

 the relative proportions used; so much depends on 

 the poverty or richness of the old surface mould, on 

 the sterility or semi-fertility of the subsoil, and on 

 the quality of the new earth added. Sometimes the 

 existing soil is so rich and deep that neither better 

 compost nor any considerable portion of subsoil need 

 be added. As a rule, however, both will be necessary 

 to get ami;hing like a i^roper depth for horticultural 

 purposes ; and it is seldom that any subsoil is so 

 absolutely barren, useless, or positively injurious, but 

 that something like a sixth portion might be incor- 



