CROPS AND SOIL IMPROVEMENT 



retically, this is not true, and the factors of pro- 

 duction on any farm are such that the largest 

 return is obtainable in only one scheme of farm- 

 ing. Practically there is rather wide liberty. 



Value of Rotation. Experience has shown the 

 benefit of variety in crops grown on land. Among 

 the advantages of crop-rotation are the following : 



1. It enables the farmer to maintain the supply 

 of organic matter in his soil. The roots and 

 stubble of a grain crop are insufficient for this 

 purpose, and the introduction of a sod or cover 

 crop is helpful. 



2. It permits the use of legumes to secure cheap 

 supplies of nitrogen. 



3. Some plants feed near the surface of the 

 ground, and the use of other plants which send 

 roots deeper adds to the production. 



4. Some crops leave the soil in bad physical 

 condition, and the use of other crops in the rota- 

 tion serves as a corrective. 



5. The keeping of livestock is made more 

 feasible and profitable, and this leads to increase 

 in farm manures. 



6. In a proper succession of crops the soil is 

 covered with living plants nearly all the time, 

 and thus is prevented from washing or leaching. 



[150] 



