CHARACTERISTICS OF DIFFERENT SOILS 217 



rocks ; in fact, the whole vegetation is one of the most interesting 

 to study. A few plants also refuse to grow on calcareous soils; 

 among these the most widely known are Rhododendrons and some 

 of the Heaths. 



ALLUVIAL SOILS. On the alluvial soils the richest land of 

 the country is to be found, though often, as it is subject to floods 

 or has permanent water but a short distance below the surface, it 

 is not suitable to arable cultivation but remains in permanent 

 pasture. The fertility of these soils is due to the fact that neither 

 coarse sand nor clay predominate in them ; they consist of a 

 very even mixture of particles of other soils that have been graded 

 by running water. Moreover, the subsoil, as deep as the deposit 

 extends, is enriched with humus, because it has once been soil. 

 There is generally a sufficiency of carbonate of lime ; indeed, 

 without it really rich soil is hardly possible. 



The rich pastures, and it is only on alluvium as a rule that 

 true " fattening " land is to be found, are largely covered with 

 Rye-grass, to which they owe their shining effect in the sunshine ; 

 on drier poorer areas Crested Dogstail and Squirreltail Grass are 

 common. The spots where the drainage is deficient are generally 

 marked by coarse tufts of Aira, or by the presence of Rushes and 

 the small sedges known to the farmer as Carnation Grass. 



The characteristics of the alluvial soils are also shared by 

 certain loams that are of sedentary origin ; these are the typical 

 soils of arable cultivation, however they may have arisen well 

 tempered mixtures of sand and clay, not too stiff to hinder percola- 

 tion and yet fine enough both to retain water and lift it by capil- 

 larity. They also contain sufficient carbonate of lime to remain 

 healthy and work freely. Several weeds are characteristic of these 

 soils, and are generally regarded as signs of fertile land in good 

 cultivation, such are Chickweed and Groundsel, Fat Hen, Stink- 

 ing Mayweed and Sow Thistle, the Speedwells and the small 

 Spurges, Pimpernel, and Goose Grass. The typical tree of the 

 loamy soils is the Elm, while good land is also generally indicated 

 by strong Hawthorn hedges, clean and free from lichen. 



On the low-lying alluvial soils spots can often be found where 

 either through insufficient drainage or the occurrence of springs, 



