GENERAL PRACTICE. SOILS AND SUBSOILS. 29 



Clay soils contain above 50 per cent, of clay a combination of silica with alumina 

 and quickly absorb water, oils and fatty substances, some retaining 70 per cent, of 

 water, and in that state useless. Clay dries slowly, shrinks, cracks and readily takes 

 up humus and humic acid, and is durably fertile. Clay also contains other substances, 

 such as oxide of iron, free and insoluble silica, lime, magnesia, potash, soda, &c. 

 Oxidation of iron gives colour to clays protoxide, brown ; peroxide, red ; and 

 hydrated protoxide, blue or greenish. Clay soils are unfitted for fruit trees until 

 weathered, improved by draining, liming, deep stirring, and manuring. When sub- 

 jected to cultivation, so as to have a foot in depth or more of sufficiently ameliorated 

 porous soil to allow heat, air and water to enter freely, clays become very productive, 

 and are not so soon exhausted as loams, suiting all kinds of fruits. 



Marly soils are not so retentive of moisture as clay, nor so porous as calcareous soils. 

 Clay marls, consisting of 50 per cent, or more clay, are too stiff for fruit trees ; but 

 those containing much soluble silica are very suitable for mixing with soils that are 

 too light and porous for the production of stone fruit, and are particularly valuable in 

 cases of gumming, where lime is not always effectual, through, we apprehend, a 

 deficiency of soluble silica. Loamy marl is perhaps the most suitable soil for fruit 

 trees, particularly those bearing stone fruits, notably plums, and ensures heavy crops 

 with profitable returns for the manurial agents employed. Sandy marls, until worked, 

 enriched and made darker in colour by manuring, or humus, are not good fruit soils. 



Calcareous soils vary greatly in nature and texture. When sandy they are too 

 light, though not so liable to burn as siliceous soils, and are particularly suited to the 

 apricot ; if clayey they are too cold and wet. When, however, a considerable quantity 

 of clay and sand enter into their composition, as occurs when the chalk or limestone 

 base is covered with a loamy deposit, the soil is fertile and of a kind that drought does 

 not readily affect. Generally, calcareous soils may be rendered available for fruit cul- 

 ture, particularly stone fruits. 



Peaty soils, which include vegetable moulds, are rich in humus but deficient in loam. 

 In the absence of loam and lime they are sterile, but additions of these essentials, with 

 adequate drainage, render them fertile. Judiciously treated they produce raspberries, 

 currants of all sorts, particularly black ; strawberries, and even pears on the Quince ; also 

 apples on the Paradise stock, not merely of an average but of a very high order. The clear 

 air, the resources of moisture, the summer heat, all combine to give a fitness to our wastes, 

 not in all but in judiciously selected situations, for fruit culture, which, if utilised, would 



