4 BULLETIN 625, U. S. DEPARTMENT OF AGRICULTURE. 



also shows that in this ease the variation in profits for the farm 

 groups was not due to the difference in the percentage of rotation 

 area in summer fallow. 



It will be seen from the two foregoing tables that an}^ cropping 

 system which either will increase yields or reduce the amount of land 

 devoted to summer fallow without decreasing the crop yields will 

 materially increase farm profits on these farms. It will, therefore, 

 be the purpose of the following pages to present methods of crop 

 improvement through the use of proper cropping systems, and also 

 to show how the percentage of rotation area in summer fallow may 

 be reduced without materially affecting the yields. 



METHODS OF INCREASING FARM PROFITS. 



The effect on crop yields of eliminating summer fallow from the 

 rotation was shown in a farm survey on the silt loam soil farms of 

 the Willamette Valley, Oregon. For more than 40 years this section 

 grew wheat and oats by the summer fallow system. The farm prac- 

 tice followed during this period was almost identical with that of 

 eastern Washington, eastern Oregon, and northern Idaho at the 

 present time. The crop yields gradually decreased from year to 

 year until farming became so unprofitable that a change had to be 

 made in the cropping systems. Legumes were introduced into the 

 crop rotation and the amount of land devoted to summer fallow was 

 decreased until in 1912 only 2.7 per cent of the rotation area was 

 idle. 



Table III. -Relation of summer fallow to crop yields on 144 silt, loam soil farms in the 



Willamette Valley, Greg. 



Number of farms '. . . 127 



Average yields per acre: 



Potatoes (bushels) 155. 9 



Wheat (bushels) [ 21. 9 



Oats (bushels) j 37. 9 



Hay ( tons) i 1. 94 



Crop index I 101 



In Table III is given a comparison of per-acre yields between 

 farms having summer fallow and those having none in the Willa- 

 mette Valley. It will be seen that farmers on the silt loam soil in 

 the Willamette Valley eliminated summer fallow from their rotation 

 without reducing the average cr<^p yield. Wheat was the only crop 

 which produced more per acre on farms with summer fallow than on 

 those without. These results were accomplished through the intro- 

 duction of legumes, principally clover, into the rotation. 



