Nature, of Soils. 5 71 



account of its limited area, is almost always so greatly modified 

 by improvements and the addition of manures. 



Besides this primary division of soils according to their con- 

 stituent parts, there is another distinction to be considered, 

 namely, in regard to the nature of the upper layer, or surface 

 soil, and of the stratum immediately below, termed the sub- 

 soil, or subjacent rock, as the case may be. The surface of 

 arable soil ranges from an inch or two to several feet in thick- 

 ness, and is equally variable in the class of vegetation it will 

 support. Greater importance perhaps attaches to the nature 

 of the subsoil than is usually accorded to it, for on this de- 

 pends the necessity or otherwise of artificial drainage, and the 

 choice of trees, shrubs, and herbs that will permanently flourish 

 in certain situations. Its thickness, as well as its mineral- 

 ogical composition, is, of course, indeterminate. It may con- 

 sist of solid rock, or beds of gravel, sand, &c., or it may also 

 be composed of soil suitable for cultivation, and will thus 

 serve to enrich the surface layer when it has been more or less 

 exhausted by the crops taken from it. In the case of a heavy, 

 impervious clayey subsoil, artificial drainage is beneficial, or, 

 as in some instances, indispensably necessary to ensure success 

 to the cultivator, *' 



It comes within our province to say but little respecting the 

 improvement or enriching of ground by the addition of natural 

 and artificial manures. To effect this object it is obvious that 

 the nature of the soil to be manured should be considered ; for 

 some manures or moulds that would improve a heavy loam or 

 clay would deteriorate the quality of a light sandy loam, and 

 vice versa. Another thing to take into consideration is the use 

 to which the ground is to be put. Luxuriance in the growth of 

 some things is undesirable, as for instance in small shrubberies, 

 and where tender subjects are planted. And then different 

 subjects delight in different soils. A lawn rarely requires any 

 stimulating manures, as they induce the growth of coarse 

 herbage. We have seen a good piece of grass spoiled by the 

 injudicious application of liquid manure. Except for hot-beds 

 and the purpose of mulching the surface of the soil around 

 newly-planted shrubs and trees to diminish the amount of 

 evaporation in dry hot weather, little use is made of what 

 is termed green dung in the pleasure-garden. Thoroughly 

 rotten leaves (leaf-mould), fibrous turf, and farm-yard manure, 

 wood-ashes, soot, lime, sand, &c., are employed according to 



