SOILS. GENERAL CONSIDEKATIONS. 107 



have a strong texture, and contain a high percentage 

 of sugar ; but, as these soils are not common, the com- 

 bination with some other soil becomes necessary. We 

 have at our disposal various manures and fertilizers, 

 but these, unless in very large quantities, will not pro- 

 duce the desired effect. 



If we now consider various clays, having alumina 

 in great excess, these will produce roots also very 

 inferior, as here the powers of absorption are too great, 

 and but little evaporation will follow, and when in 

 wet, cold climates they will be shortly choked with 

 aquatic cryptogamia. These varieties of soils, more 

 especially when pure, offer great resistance to the pene- 

 tration of the plant, and in many cases the cultivation 

 of any root could not possibly take place. Here then, 

 again, it becomes important to have combination with 

 another soil. As a pure calcareous one will have 

 many of the above disadvantages, it should also be 

 combined in given proportions with an argillaceous 

 or sandy one in order to obtain satisfactory results. 

 The sablo-calcareous are excellent on the condition that 

 they contain a certain amount of humus. The action 

 of the chalky portion is not exactly known, but it is 

 generally admitted that when' this is in large propor- 

 tions the quality of the root is much improved. 



The researches of Leplay on this subject have been 

 most interesting. It would be difficult to say what this 

 action is exactly owing to, but some contend that the 

 lime has taken an active part in decomposing, under 



