THE CHOICE OF CROPS 51 



permanently changed conditions, the system of farming 

 should be quickly adjusted. 



The change in relative prices may result from a change in 

 the number of uses to which a staple crop like cotton or corn is 

 put, or it may result from an expansion of the area available for 

 the one crop without a like expansion of the area available for 

 the other. The expansion of cotton production in Brazil 

 or west central Asia or India might reduce the price of cotton 

 relatively to that of corn so that corn would replace cotton on 

 the margin of the cotton belt of the United States. It will be 

 noted that the stability of the system will be greater in the 

 heart of the corn belt and in the heart of the cotton belt than 

 on the margin between these two regions. 



Fluctuations in the rent of land without any change in the 

 relative values of the products may necessitate a change in 

 crops. Suppose, for example, that the rent of a given piece 

 of land is three dollars per acre, and that the net profit per acre 

 is five dollars when the land is devoted to corn, and that the 

 net profit is twenty dollars per acre when the land is devoted to 

 sugar beets ; but that the farmer can operate thirty-five acres 

 of corn and only seven acres of beets. Then he could win one 

 hundred and seventy-five dollars net profit by producing corn, 

 and only one hundred and forty dollars by producing beets. 

 But, suppose the rent of the land should rise to five dollars per 

 acre, without any change in the prices of the products or in the 

 costs of production. The profits per acre of corn would then 

 be three dollars, and that of an acre of beets would be eighteen 

 dollars, so that with the same acreage of these two crops, the 

 total net profit which he could win from the production of corn 

 would be reduced to one hundred and five dollars, while that 

 from the beets would have been reduced to one hundred and 

 twenty-six dollars only. In this hypothetical case, the rise in 

 the rent would result in a subtraction of only fourteen dollars 

 from the total profits of the beet crop, while it would result in a 

 reduction of the profits on corn of seventy dollars, so that the 

 crop which was the more profitable before the rise in the rent 

 would become the less profitable as a result of the rise in rent. 



