SOILS THEIR CHARACTERISTICS. 41 



its stiffness, and the lack of which in sufficient quantity 

 subjects it to the attacks of rust. Silica usually forms a 

 small proportion, too, of grains, legumes, and succulent 

 roots. 



For garden purposes, the only kind of sand suitable is 

 that which is tine and has been rounded by moving water. 

 The angular particles of road sand form hard, impermea- 

 ble masses, and should never be employed. (Lindley.) 



A loamy .sand i i a better soil than the preceding, and 

 contains from ten to twenty per cent, of clay. These light 

 soils are best adapted to tap-roots and bulbs and for 

 striking cuttings, while those heavier are better fitted 

 for plants with fibrous roots. 



A sandy loam contains between twenty and thirty per 

 cent, of clay, while all soils containing from thirty to fifty 

 per cent, of clay are classed as ordinary loams. 



In a garden designed for the cultivation of a variety of 

 plants, both a light and a moderately heavy soil are de- 

 sirable. But the best soil for general purposes is a loam 

 of medium texture, rather li^ht than otherwise, arising 

 from a suitable admixture of the two, as they reciprocally 

 correct the defects of each other. Where the other essen- 

 tials are present naturally, or added by man, such a soil 

 is suitable for the production of nearly all garden crops. 

 Any soil, by judicious culture, draining, and amelioraters, 

 or amendments, can be converted into such a loam. 



Lime in greater or less proportions is generally present 

 in soils, commonly as a carbonate. It is sparingly solu- 

 ble in water, and is especially, when combined with acids, 

 as in the sulphate (gypsum), or the phosphate of lime 

 (bone earth), an important portion of the food of our 

 most useful plants. There are some plants, however, as 

 the Kalmia, to which its presence, to any appreciable ex- 

 tent in soils, is injurious. Any one of the foregoing soils 

 that contains from five to twenty-five per cent, of lime is 



