io6 



Kl.ADINGS IN Kt'KAL ECONOMICS 



Table 4 shows the comparative yields of corn, wheat, oats, bar- 

 ley, rye, buckwheat, potatoes, and hay, for every year since 1 866. 

 Each crop was compared with its 1866 yield as 100 per cent. 

 These percentages were then averaged in order to get the per- 

 centage yield for each year. If one crop had more acreage than 

 another, it is given proportionately more weight in determining 

 the average. The figures are what is known as a weighted aver- 

 age. 1 This is the fairest possible way of comparing the yield of 

 different acres, since it gives every acre equal weight. 



The chart on page 107 shows the comparative yields for states 

 east of the Mississippi River. This curve shows a period of general 

 low production during the eighties and the early nineties. During 

 that period prices were low and farmers were having hard times. 

 Since 1896 the yields in these states have only once dropped 

 below the 1866 crop; that was in the very dry year of 1901. 

 Never before have the eastern states shown such high yields as 

 in the last eight years considered. In four of these years the 

 crops have been better than ever before produced. In every year 

 the crops have been good. 



********** 



\\7iy are crop yields increasing? The writer does not believe 

 that changes in crop yields can be taken as a measure of soil 



1 The method of calculating the comparative crop yields, or the crop index, is 

 best shown by an example : 



Percentage yield, or crop index = 



320,849,630 

 254,543,000 



126 per cent 



