12 



CASSELL'S POPULAE GARDENING. 



ground-level into a terrace or artificial wide prome- 

 nade with tlie worthless diggings. And the fertile 

 surfaces have heen entombed where we least expect 

 it, and barren earths without either texture or 

 strength substituted for them. 



Testing tlie 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 civil 

 engineers, who wUl begiu 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, wiU 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- rocky 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 o£E that at 

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

 But he can measure 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 soil, how came 

 they to be more numerous in one place than another, 

 and that before the surface soil had been deepened ? 



Leaving 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 vitally important is it that the- 

 subsoil should be levelled, that the advice 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 tUth wOl be found of one imiform depth 

 throughout. There are, however, dips in the surface 

 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 wiH enable him the better to calcu- 

 late on the depth of surface 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,. 



Fig. 1.— Grround Dug out to Level 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 space 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 do-wn any strict rules regarding 

 the relative proportions used; so much depends on 

 the poverty or richness of the old surface mould, on 

 the steriHty 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 anything like a proper 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- 



