LEGUMES AND GRASSES 



53 



was a comparison between grain- 

 crop rotations and the so-called 

 mixed-farming rotations, which in- 

 cluded legume and nonlegume hay 

 and intertilled crops. 



Beneficial effects of mixed-farm- 

 ing rotations over straight-grain 

 rotations were outstanding in the 

 Black and Gray wooded soil zones. 

 In the drier Brown and Dark Brown 

 soil zones, these rotations possessed 

 no advantage over grain rotations. 

 Discussion of results at Lethbridge, 

 Alberta; and Swift Current and 

 Indian Head, Saskatchewan follow. 



Lethbridge, Alberta. — The experi- 

 ments were located on Dark Brown 

 (Chestnut) loam soil. Annual pre- 

 cipitation averaged 15.8 inches. 

 Results with mixed-farming on dry- 

 land were not satisfactory. Weeds 

 were controlled in grain rotations 

 as effectively as in mixed-farming 

 rotations. Yields from biennial or 

 perennial hay crops were low and 

 usually contained a large amount 

 of weeds in the first year after 

 seeding. Pea and oat hay alone 

 yielded two to three times as much 

 hay as biennial or perennial hay 

 crops. In grain rotations, farm 

 manures and legume hay crops on 

 dryland did not increase yields of 

 the following crop over yields 

 without these practices. Summer 

 fallow wheat yields were ex- 

 ceptionally good in the grain rota- 

 tions and did not tend to decline. 



Swift Current, Saskatchewan. — 

 The experiments were located on 

 Haverhill loam soil (Brown soil). 

 Annual precipitation averaged 14.5 

 inches. The mixed-farming rota- 

 tion was a failure. Wheat yields 

 after grass were depressed. The 

 hay crop usually included large 

 amounts of weeds, so quality was 

 poor. Yields of oat hay were much 

 larger than those of biennial or 

 perennial hay. Where hay crops 

 were grown, it was concluded that 

 the crop should be left in production 

 for several years. 



Indian Head, Saskatchewan. — 

 Experiments were located on Black 

 Indian Head clay soil (Chernozem) . 

 Annual precipitation averaged 17.7 

 inches. A serious disadvantage of 

 the fallow, wheat, wheat rotation 

 was infestation with wild oats, 

 especially in the second-year wheat 

 crop. Hay crops did not yield well. 

 Stands were difficult to obtain in a 

 dry year, and the first-year hay 

 always contained a large percent- 

 age of weeds. The authors con- 

 cluded that hay should be left in 

 production for several years rather 

 than used for 1 or 2 years in a grain 

 rotation. Oat hay yielded more 

 than perennial hay crops. 



Hopkins and Leahey (87) con- 

 cluded that plowing under a crop 

 for green manure was not advisable 

 in the Prairie Provinces. Usually 

 the yields of wheat the following 

 year were less than were obtained 

 after a regular summer fallow. In 

 areas with sufficient moisture, it 

 was preferable to harvest the crop 

 for hay rather than plow it under 

 for green manure. 



They found that, in the Black 

 soil zone (Chernozem), yields from 

 a straight-grain rotation declined 

 with time. Originally the grain 

 rotations produced the greatest 

 yields, but by 1944, mixed-farming 

 rotations were superior. 



In 1948, Doughty (14) discussed 

 the maintenance of organic matter 

 in Brown soils. Crop-yield data in 

 the Brown soil zones of Alberta 

 and Saskatchewan did not indicate 

 any appreciable decrease in yield 

 during the previous 25- to 30-year 

 period. Yields showed a decrease 

 during the first 4 to 5 years after 

 plowing the sod. After this initial 

 period, yields showed no decrease 

 that could be attributed to a loss in 

 productivity. 



Loss of nitrogen and organic 

 carbon after plowing grass sod was 

 more rapid than the accumulation 

 when grass was reestablished (14) - 



