TYPES OP VEGETATION 19 



fertile, because of the relatively large amount of humus — 

 i.e., rotting plant and animal remains — present in it. 

 Some cultivated land has, however, been reclaimed from 

 moorland and fen, and some even from the sea. 



Arable land is, as the name implies, land under the 

 plough, and is utilized for the raising of crops. The nature 

 of the crops raised depends, in the first place, upon the 

 cMmate ; secondly, upon the soil ; and, lastly, upon the 

 conventional needs of the resident commimity or the 

 demands of neighbouring or distant profitable markets. 



By cultivation, man so modifies the soil-factors that 

 the soil itself plays a part vastly inferior to that of cUmate 

 in deciding the most suitable crop for a locahty. Indeed, 

 under the methods of modem agriculture, the nature of 

 the soil is quite a minor matter, granted, of course, a 

 certain minimum of fertility. For this reason the great 

 cereal crops Uke wheat, maize, and oats grow on all kinds 

 of soil within limits which are climatically determined. 

 The water-supply dominates all other factors in cultivated 

 soils. 



Agriculture and Farming in the British Isles. 



1. Wheat. — In this country wheat can only be grown 

 with profit — at least, under present agricultural methods 

 — ^where the mean summer temperature during the 

 ripening of the ear is greater than 56° F. (13° C), and 

 the rainfall is less than 30 inches annually. These 

 limiting factors readily determine the range of wheat- 

 cultivation in the British Isles. They exclude most of 

 the upland slopes over 500 feet, large parts of the West 

 of England, aU Wales, and most of Scotland and Ireland. 

 In countries Hke ours, where the winter is not severe 

 enough to destroy the seedlings, wheat is usually sown 

 in the autumn. In Canada, on the other hand, where 

 the ground is frozen hard for several months, it is sown 

 in the spring, as soon as the snow has disappeared and 

 the ground is sufficiently thawed to be broken by the 

 plough. 



Wheat flourishes best in a dry, sunny region, and the 

 winter conditions determine whether the sowing should 

 be before or after the frost. The great wheat-districts 

 of the world are thus the grasslands — e.g., the steppes of 



