ROTATION OF CROPS 199 



if good temporary leys are difficult to 

 secure. 



In some districts conditions of soil and 

 climate favour the growth of certain crops, 

 or encourage certain systems of stock-keeping. 

 Thus, with a moderate rainfall and heavy soil, 

 the tendency is in the direction of putting a 

 large area of the farm under wheat or beans. 

 In other districts, barley-growing may be 

 attractive, a system of farming which is 

 usually closely associated with the cultiva- 

 tion of turnips. Then, again, the whole 

 system of cropping may be arranged with a 

 view to keeping as large a head of sheep 

 as possible ; in another district dairying 

 may be the principal object in view, and 

 this necessitates the growth of large quantities 

 of bulky fodder, and of abundant supplies 

 of green food. The possibility or otherwise 

 of making cleaning crops a regular feature 

 of a rotation, has an important bearing upon 

 the percentage of tillage land that must be 

 bare-fallowed, for if a cleaning crop cannot 

 be depended upon every four or five years, 

 the land must, at some such interval, be 

 left uncropped throughout a season to permit 

 of the eradication of weeds. The occurrence 

 of disease in certain crops often entails 

 drastic modifications of a rotation. For 



