52 MISCELLANEOUS PUBLICATION 95 2, U.S. DEPT. OF AGRICULTURE 



eraged 36 percent for the 37-year 

 period. Losses of organic carbon 

 averaged 42 percent. Neither legume 

 nor rye green manures were effective 

 in reducing nitrogen and carbon 

 losses. 



Rotational effects of grass and 

 alfalfa on the loss of soil nitrogen 

 were studied at Mandan, Dickinson, 

 Sheridan, and Archer. Except for 

 alfalfa at Archer, grass and alfalfa 

 reduced nitrogen losses in the sur- 

 face soil. Neither grass nor alfalfa 



maintained the nitrogen at its 

 original level. Losses of total nitro- 

 gen from the soils resulted in sim- 

 ilar losses of nitrate-nitrogen pro- 

 ducing capacity. 



Data from Mandan, Dickinson, 

 Havre, Sheridan, Archer, and Hays 

 indicated that row-crop yields de- 

 clined with years of cropping, while 

 wheat yields did not change signifi- 

 cantly. There was little relationship 

 between the change in soil nitrogen 

 and the change in yield. 



CANADIAN PRAIRIE 



PROVINCES 

 PROBLEMS 



SOIL-MANAGEMENT 



Yields 



Results from the Prairie Prov- 

 inces of Alberta, Saskatchewan, and 

 Manitoba are presented to com- 

 plete the findings for the northern 

 Great Plains. In 1911, the Domin- 

 ion Experimental Farm Systems 

 established comprehensive experi- 

 ments in the Prairie Provinces to 

 test the value of different crop 

 rotations. 



Hopkins and Barnes (36) report- 

 ed the yields from these rotations 

 in 1928. One of the experiments 

 was conducted to determine the 



value of plowing under legume crops 

 in 3-year rotations of green-manure 

 fallow, wheat, and oats (table 36). 



These experiments showed that 

 yields were not increased by plowing 

 under peas or vetch. 



In 1944, Hopkins and Leahey 

 (37) published a second report on the 

 results of crop-rotation experiments 

 conducted on the Dominion Experi- 

 mental Farms in the Prairie Prov- 

 inces. This report covered more 

 than 30 years of records from dif- 

 ferent cropping systems. An im- 

 portant objective of the report 



Table 36. — Average yields of spring wheat and oats in 3-year rotations with 

 various treatments during the fallow year, Brandon, Manitoba, and Indian 

 Head, Saskatchewan, 1928 l 





Average yield, per acre, at — 



Treatment during fallow year 



Brandon 



Indian Head 





Spring 

 wheat, 

 15-year 

 means 



Oats, 

 13-year 

 means 



Spring 

 wheat, 

 9-year 

 means 



Oats, 

 9-year 

 means 



Summer fallow. _ __ 



Bushels 

 34. 7 

 33.8 

 32.8 



Bushels 



71. 1 



72. 

 68.3 



Bushels 

 34. 2 

 33.5 

 35.5 



Bushels 

 55. 6 



Peas plowed under early July 



Vetch plowed under late July 



56.0 

 55.0 



Data from Hopkins and Barnes (36) . 



