16 BULLETIN 705^ U. S. DEPARTMENT OF AGRICULTURE. 



RELATION OF CLOVER TO CROP YIELDS. 



Of the leguminous crops grown on the silt loam farms, clover was 

 by far the most important, with vetch second. In Table XII the 

 farms are arranged in groups according to the percentage of the field- 

 crop area devoted to clover. 



60 



50 



40 



O 30 



20 



10 







y 





y 



0^ 





/ 







f 



. ^^H^AT 



/ / 



/ / 







I/-- 



r 





IE 2 6 44.8 



AVE.RAGE PERCENTAGE OF FIELD CROPS IN LEGUMES 



Fig. 4. — Percentage of increase in crop yields with increase in percentage of field crop 

 area in legumes on 144 silt loam farms in Marion and Polk Counties, Oreg. (1912). 



Table XII. — Relation of percentage of field-crop area in clover to crop yields on 144 silt 

 loam soil farms, Marion and Polk Counties, Oreg. {1312). 



Item. 



All 

 farms. 



Per cent of field-crop area 

 in clover. 



No 

 clover. 



Less 

 than 20. 



20 or 

 more. 



Number of farms 



AveraRe per cent of field-crop area in clover 

 Crop yields per acre: 



Potatoes (bushels) 



Wheat (bushels) 



Oats (bushels) 



Hay (tons) 



Crop index 



144 

 12.0 



150.2 



22.0 



37.7 



1.94 



100 



140.4 

 20.5 

 34.1 

 L82 

 92 



45 

 11.1 



159. 

 22.1 

 38.2 

 2.00 



102 



38 

 32.7 



163. 7 

 24.9 

 45.5 

 2.05 

 113 



