54 MISCELLANEOUS PUBLICATION 9 5 2, U.S. DEPT. OF AGRICULTURE 



Return of all crop residue was 

 recommended as the most practical 

 way to compensate for losses of 

 organic matter from medium- and 

 fine-textured soils of the Brown 

 soil zone. For coarse-textured soil, 

 grass seeding was generally 

 recommended. 



In 1954, Hill (29, 30) discussed 

 wheat yields and soil fertility on 

 the Canadian Prairies after a half 

 century of farming. Cereal pro- 

 duction alternating with fallow was 

 the usual cropping practice in the 

 Brown soil zones of southern Al- 

 berta and Saskatchewan where mois- 

 ture was a limiting factor. Continued 

 use of the practice was of chief 

 concern to farmers and agronomists 

 in the area. 



Hill (30) tabulated the long-term 

 and 10-year average yields of con- 

 tinuous wheat and fallow wheat at 

 Lethbridge, Alberta (table 37). 

 The data indicate that yields did 

 not decline with time with these 

 cropping systems. 



Hill (30) found that during 40 

 years of cropping at Lethbridge, 

 average losses of 25 percent nitro- 

 gen and 19 percent organic matter 

 have occurred in the grain rotations. 

 The smallest loss was in the 10-year 

 rotation, with nitrogen and organic- 

 matter losses of 14 percent and 5 

 percent, respectively. 



At Indian Head, Saskatchewan 

 (30), wheat yields after fallow 

 showed no trends over a 40-year 

 period. Wheat after wheat showed 

 a downward trend. Wild oats was 

 believed to be the cause, because 

 this weed became a serious problem 

 in later years. 



At Brandon, Manitoba (30), 

 yields of wheat on fallow were 

 maintained. Yields were somewhat 

 better in the manured rotation than 

 those in the nonmanured rotation, 

 but yield increases were not enough 

 to pay the cost of manure applica- 

 tion. Yields of second and third 

 crops after fallow were seriously 

 affected by infestations of wild oats 

 in later years. 



Hill (30) concluded that the 

 wheat, fallow system could be con- 

 tinued profitably in western Canada 

 for many years provided erosion 

 and weeds were controlled. 



Newton and coworkers (62), in 

 comparing virgin and cultivated 

 soils, reported on the analysis of 

 soil samples from 85 locations in 

 Alberta, Saskatchewan, and Mani- 

 toba. Average period of cultiva- 

 tion was 22 years. Losses of or- 

 ganic carbon and nitrogen from the 

 surface 6 inches of Brown, Dark 

 Brown, and Black soils were similar. 

 Organic carbon loss was 20 percent 

 of the original content, and nitro- 



Table 37. — Long-term and 1941-50 average yields from continuous wheat 

 and fallow, wheat rotations, Lethbridge, Alberta l 



Rotation 



Average grain yield, per 

 acre, for — 





1912-51 



1941-50 



Continuous wheat 



Bushels 



12.2 



27. 1 



2 25. 8 



2 25. 4 



Bushels 



12. 1 



Alternate wheat and fallow 



27. 1 



Wheat, wheat, fallow 



2 28. 3 



10-year including alfalfa 8 



2 25. 5 







J Data from Hill (SO). 

 * Fallow wheat yields. 

 » Fallow (manured), winter wheat, oats, alfalfa, alfalfa seed, alfalfa seed, alfalfa seed, fallow, corn, wheat. 



