84 THE SOILS AND CROPS OF THE FARM. 



long series of years, without change, or rest to the 

 land. In a good many cases in this country, where 

 some special crop has been thought particularly pro- 

 fitable, it has been shown possible to grow it annually 

 for many years on the same land, by reasonable use 

 of manures. 



In exceptional cases such a course of continued 

 cropping without change may be wise and profitable. 

 The general practice of good farmers and abundant 

 experimental evidence, however, show that a rotation 

 of crops is usually wise. 



Bea^on^^ for Rotating Cropis, — The reasons 

 why a rotation of crops is usually good practice may 

 be divided into two classes: Those which concern the 

 convenience and probable immediate profit of the 

 farm work, and, secondly, those which relate to main- 

 taining or increasing the fertility of the soil. 



Aside from the usual arguments in favor of produc- 

 ing something of a variety of crops on a farm, such as 

 that this practice reduces the risks of the farmer, 

 since it is not probable that all will be poor in yield or 

 low in price, and that it better distributes the work 

 of the year, enables the farmer better to provide for 

 live-stock, etc., all of which have some bearing on ro- 

 tation, it is also true that one crop may more profit- 

 ably follow another than itself, from its leaving 

 the soil in better condition. Land long kept in crops 

 which are not cultivated while growing is liable to 

 become infested with weeds. 



The most important reason for rotation is that the 

 practice helps keep up the productiveness of the land. 

 Three reasons why this is true may be given: 



1. While all farm crops are made up of the same 



