The Chemistry of Garden Crops 



capable of carrying more or less of all the vegetables and fruits that 

 find a place in the catalogue of domestic wants. That in certain 

 cases he must fail at certain points is inevitable; nevertheless his 

 aim will be, and must be, of a somewhat universal kind, and a clear 

 idea of the relations of plants to the soil in which they grow will be 

 of constant and incalculable value to him. 



We are bound to say at the outset that a complete essay on 

 the chemistry of vegetation is not our purpose. We are anxious to 

 convey some useful information, and to kindle sufficient interest to 

 induce those who have hitherto given but slight attention to this 

 question to inquire further, with a view to get far beyond the point 

 at which we shall have to quit the subject. 



Plants consist of two classes of constituents the Inorganic, which 

 may be called the foundation ; and the Organic, which may be con- 

 sidered the superstructure. With the former of these we are princi- 

 pally concerned here. A plant must derive from the soil certain 

 proportions of silica, lime, sulphur, phosphates, alkalies, and other 

 mineral constituents, or it cannot exist at all; but, given these, 

 the manufacture of fibre, starch, gum, sugar, and other organic 

 products depends on the action of light, heat, atmospheric air, and 

 moisture, for the organic products have to be created by chemical 

 (or vital) action within the structure, or, as we sometimes say, the 

 tissues of the plant itself. To a very great extent the agencies 

 that conduce to the elaboration of organic products are beyond our 

 control (though not entirely so), whereas we can directly, and to a 

 considerable degree, provide the plant with the minerals it more par- 

 ticularly requires ; first, by choosing the ground for it, and next by 

 tilling and manuring in a suitable manner. A clay soil, in which, in 

 addition to the predominating alumina, there is a fair proportion 

 of lime, may be regarded as the most fertile for all purposes; 

 but we have few such in Britain, our clays being mostly of an 

 obdurate texture, retentive of moisture, and requiring much cultiva- 

 tion, and containing, moreover, salts of iron in proportions and forms 

 almost poisonous to plants. But there are profound resources in 

 most clays, so that if it is difficult to tame them, it is also difficult to 

 exhaust them. Hence a clay that has been well cultivated through 

 several generations will generally produce a fair return for whatever 

 crop may be put upon it. Limestone soils are usually very porous and 

 deficient of clay, and therefore have no sustaining power. Many 

 of our great tracts of mountain limestone are mere sheep-walks, and 

 would be comparatively worthless except for the lime that may be ob- 



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