ROTATION OF CROPS. 93 



CHAPTER XIX. 



ROTATION OF CROPS. 



IMPORTANCE OF ROTATION. If we get a large yield of any 

 crop from a certain field, should we not grow the same crop 

 year after year ? This is done, for instance, on the rich prairie 

 soils, where wheat has been grown year after year upon the 

 same soil. In former times this was done also on our soils 

 when they were new and rich. But what has been the result ? 

 The soils of many farms have run down and good crops are 

 got only by heavy manuring. In the best farmed countries of 

 Europe, where, after the experience of hundreds of years, 

 larger yields of wheat and other crops are obtained than 

 we get in Canada, it has been found advisable to change the 

 crops grown from year to year. The experience of Europe and 

 of Canada both prove that the best farmers succeed in crop 

 growing only by rotating or changing their crops. 



REASONS FOR ROTATION. i. The different crops, as we have 

 seen, are all made up of the same elements, and take up 

 food from the soil ; but they do not all take up soil food 

 of the same amount or in the same form. Thus the potato, 

 tobacco, and fruit trees require a great deal of potash ; 

 the grain crops take up more phosphates. The crops differ 

 in their feeding just as animals differ. The dog does not 

 eat just what the cat does, nor the horse just whit the pig 

 does. If cattle and sheep are pastured together, the sheep 

 will pick out certain weeds and grasses, and the cattle may 

 prefer others. Wheat, for instance, requires nitrates as one 



