ROTATION OF CROPS 201 



under such management, the land in the 

 course of time regained a certain amount of 

 fertility, and it became possible once more 

 to put it through a course of cropping. One 

 finds this system of agriculture prevalent 

 over large areas of the North American 

 Continent at the present time. In the west 

 of the United States and of Canada, farmers 

 are annually taking wheat crops off the 

 recently reclaimed prairie, no farmyard 

 manure whatever being given, in fact much 

 of the straw is burned in the process of 

 stoking the engine of the thrashing machine 

 that annually visits the holding. For a 

 longer or shorter series of years the crops 

 obtained leave a more or less satisfactory 

 margin of profit, but in the course of time 

 the yield falls to such a low ebb that nothing 

 remains to the cultivator after outgoings 

 have been met. It then becomes necessary 

 either to apply manure to the land or to 

 abandon it. In the older districts of the 

 United States and Canada, where an in- 

 dustrial population has gathered in certain 

 centres, farmers find that it is profitable to 

 maintain stock for the production of meat 

 or milk, and the presence of stock necessarily 

 means the consumption as food and litter 

 of large quantities of straw, with the con- 



