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



Table 38. — Effects of crested wheatgrass on 7 physical and chemical 

 characteristics of coarse-, medium-, and fine-textured soils in southwestern 

 Saskatchewan, 19^2 l 









Avail- 









Dry 



Wet 





Field 



Perma- 



able 



Bulk 







sepa- 



sepa- 



Type of soil and 



capac- 



nent 



mois- 



densi- 



C 



N 



rates, 



rates, 



treatment 



ity 



wilting 

 point 



ture 

 capac- 

 ity 



ty 







>0.83 

 mm. 



>0.177 

 mm. 





Per- 



Per- 



Per- 





Per- 



Per- 



Per- 



1 

 Per- 





cent 



cent 



cent 





cent 



cent 



cent 



cent 



Coarse-textured soils: 



















Cultivated land 



16.0 



5.2 



10.8 



1.43 



1.30 



0. 126 



15. 1 



61, 6 



Sod 



21.2 



6. 1 



15.0 



1. 36 ' 



1.90 



. 167 



17.9 



61. 6 



Sod decomposed: 



















5 months 



21.3 



5.9 



15.4 



1.35 



1.66 



.160 



22.6 



61.6 



10 months 



21.4 



6. 1 



15.4 



1.33 



1.45 



.150 



28.0 



61.5 



Medium-textured 



















soils: 



















Cultivated land 



25.8 



9.3 



16. 5 



1.23 



2. 10 



.214 



37.2 



41. 5 



Sod 



29. 1 



10.2 



18.9 



1. 16 



2. 61 



.259 



37.3 



50. 9 



Sod decomposed: 





5 months 



29.7 



10.4 



19.3 



1. 12 



2. 40 



.243 



42.3 



46.6 



10 months 



29.9 



10.8 



19. 1 



1. 10 



2.33 



.238 



49. 1 



49.9 



Fine-textured soils: 



















Cultivated land 



40.4 



18. 6 



21.8 



1.02 



2.08 



.214 



65. 4 



66.4 



Sod 



40.6 



19.2 



21.4 



1.04 



2. 16 



.207 



64.9 



68. 8 



Sod decomposed: 





5 months 



41.0 



19. 5 



21.5 



1.02 



2.00 



.206 



67.0 



68.2 



10 months 



40.6 



19. 6 



21.0 



1.02 



1.92 



.201 



71.8 



70. 1 



'Data from Lehane and Staple (45). 



wheatgrass were similar. Slender 

 wheatgrass produced about one-half 

 as much root material as the other 

 two grasses and was considered of 

 little value in improving soil struc- 

 ture. Crested wheatgrass was supe- 

 rior to bromegrass in increasing the 

 size of soil aggregates. The authors 

 concluded that a 5-year stand of 

 crested wheatgrass would provide 

 satisfactory restoration of soil struc- 

 ture to cultivated clay loam soil. 

 There was no indication of the 

 duration of this beneficial effect. 



Effect of adding crop residues to 

 two types of soils in pot cultures 

 was studied at Swift Current, 

 Saskatchewan (5) . The experiment 

 was carried on for 5 years. One 

 treatment consisted of one crop of 

 wheat per year grown on the wheat, 

 fallow rotations. The other treat- 



ment consisted of a similar rotation 

 but with the addition of finely 

 ground straw in amounts equal to 

 the crop produced. Data on the 

 organic matter and nitrogen losses 

 are tabulated (table 39). 



Losses of organic matter and 

 nitrogen were reduced by adding 

 straw to the soil. The authors 

 postulated that similar beneficial 

 effects would occur under field 

 conditions. 



Summary 



Green manuring was not recom- 

 mended for Brown and Dark Brown 

 soils in the Prairie Provinces. Usu- 

 ally the small-grain yields after 

 green-manure fallow were less than 

 those after ordinary fallow. 



Legume and grass crops in rota- 

 tions reduced vields of succeeding 



