ENGLISH AGRICULTURE. 33 



A clay soil is of course one in which clay predominates, a 

 sandy soil is one in which sand predominates ; and between 

 these two extremes are all the grades of loams. 



The gradations which I would suggest are as follows 

 (1) clays; (2) clay loams, that is, loams which abound in 

 the argillaceous element ; (3) loams, which are easy working 

 and friable garden soils ; (4) sandy loams, or soils which are 

 still loamy, but in which sand predominates ; and (5) sands. 

 Clay stands at one end of the series ; then clay loams ; loams 

 in the centre ; then sandy loams ; and sand, forming a series 

 which will enable us to describe very extensive classes 

 of soil. 



Lime is a staple constituent of all soils, and occurs as 

 carbonate of lime, or calcium carbonate, which, among the 

 proximate constituents of soils now under notice, is the first 

 which can be spoken of as a plant food. Clay is not a plant 

 food, sand is not a plant food, but lime can be taken up into 

 the tissues of the plant. There is a great difference in this 

 particular between lime and the other two proximate con- 

 stituents already noticed. Like sand and clay, lime does not 

 occur pure in nature, but is neutralized by acids which take 

 possession of it as a base, and form salts of lime. Carbonic 

 acid is the principal of these acids. All soils contain carbonate 

 of lime, but with the carbonate we find both the phosphate 

 and sulphate of lime. Associated with lime we get these 

 two important constituents sulphur and phosphorus; and 

 lastly, in the constant processes of nitrification, nitrate of lime 

 is formed. 



Lime is of very great use in the soil, both as a plant food 

 and on account of its physical effects. It may be spoken of 

 as intermediate in many respects between sand and clay. 

 This is proved by the experience of farmers who know that 

 lime renders a clay soil lighter, and binds together a sandy 

 soil. This means, that it is intermediate in character between 





