AND AGRICULTURE. 



47 



rious substance, and this result would often be 

 aided by supplying an additional quantity of 

 lime. 



Good and fertile land will soon become poor 

 and unproductive, if the same kind of crops are 

 raised on it year after year. If wheat or oats 

 be raised season after season from the same soil, 

 it will after a while be unable to produce a good 

 crop of either of these grains. 



The reason why a succession of crops of the 

 same kind will impoverish good land, and make 

 it unproductive, is easily seen. They take ^ 

 from the soil certain substances in large amounts, 

 until, after a while, the soil can no longer fur- 

 nish the substances required by the plants. 



Questions What is the effect of continually raising the 

 name crops on a piece of land ? Why does a succession of 

 the same crop impoverish the soil ? 



