LEGUMES AND SOIL FERTILITY 



175 





Legumes-YteU 



Fallow-Yield 



Crop 



{jso-year Periods) 



{20-year Periods) 



1st 



2nd 



3rd 



/St 



2nd 



3rd 





1848-68 



1868-88 



1888-1908 



1848-68 



1868-88 



1888-1908 



Turnips 

 Roots (lbs.) 

 Leaves (lbs.) 



5,264.0 

 600.0 



1,723.0 

 447,0 



967.0 

 242.0 



629.0 



3,067.0 

 538.0 



2,502.0 

 458.0 



Barky 



Grain (lbs.) 

 Straw (lbs.) 



38.0 

 ^>373-o 



22.5 

 1,496.0 



13.7 

 1,172.0 



37.0 

 2,244.0 



22.8 

 1,489.0 



15-9 

 1,172.0 



Wheat 















Grain (bu.) 

 Straw (lbs.) 



29.6 

 3,169.0 



21. 1 

 2,082.0 



24-3 

 2,455-0 



34-5 

 3,761.0 



23.2 

 2,420.0 



2,412.0 



The results with the barley are no better, for there is a decline 

 from the fair yield of 38 bushels per acre during the first 

 period to only 13.7 during the third. The wheat which followed 

 the legume in the rotation, and hence occupied the most favored 

 place in the system, shows a decrease of 5.3 bushels. Even the 

 yield of clover has decreased, as from 1850 to 1874 the average 

 yield was 4,165 pounds, while from 1882 to 1906 the yield was 

 only 1,246 pounds. In reality the decline in the yields is no 

 greater where fallow cultivation is practiced than where legumes 

 enter. Both systems strongly testify that rotation is not maintain- 

 ing the productive powers of this soil. And the evidence is 

 strong that the legume gets no more nitrogen from the air than 

 that which is removed with the plant. Otherwise, we should ex- 

 pect better results in the legume system than in the fallow system. 



Nitrogen Obtained from Atmosphere by Legumes. — That 

 the alfalfa when grown on fertile soil and the crop removed does 

 not increase the nitrogen of the soil is seen from experiments 

 conducted by Dr. Hopkins at the University of Illinois. The 

 experiments were made possible by the fact that many of the Illi- 

 nois soils do not normally contain the symbiotic nitrogen-fixing 



