330 



SOIL CONDITIONS AND PLANT GROWTH 



completeness only in terms of the water-supply ; the rainfall, 

 the coolness of the climate, the presence of moving under- 

 ground water, and the nature of the subsoil all have to be 

 taken into account. 



Effect of the Rainfall. — The effect of a high rainfall is to 

 bring into prominence the " sticky " properties of the fine 

 fractions, and to put into the background their water-holding 

 capacity. Thus a light soil under a high rainfall behaves 

 like a heavier soil under a low rainfall ; it is as well supplied 

 with water and on the whole behaves in the same kind of 

 way on cultivation. For example, the Stedham soil (Table 

 LXXXV.) is rather lighter than the Swanley soil, and yet in 

 virtue of its extra rainfall is more useful for farming purposes ; ^ 

 indeed, the Swanley soil is essentially a market-garden soil, 

 requiring large dressings of dung for successful cultivation. 

 The North Chapel soil is physically as good as the East Far- 

 leigh soil but agriculturally much inferior ; owing to the higher 

 rainfall it becomes somewhat too sticky to cultivate profitably 

 and so is in rather poor grass ; the East Farleigh soil, on the 

 other hand, is from a highly fertile hop garden. 



Table LXXXV. — Water-supply and Interpretation of Mechanical 



Analysis. 



Coolness of Climate. — Soils containing so much coarse sand 

 or fine sand that they would scorch or burn in a dry warm 



^ An example is given by G. W. Robinson, Journ. Ag. Set., 1917, 8, 370. 



