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TEXTBOOK OF BOTANY 



When the root systems of winter rye grass were compared with those 

 of oats, and of bluegrass under field conditions, the following relative 

 results were obtained: 



Winter rye grass 



Oats 



Bluegrass 



Number 

 of Roots 



4,700 



6,400 



84,500 



Total 

 Length 



150 ft. 



210 ft. 



1 , 250 ft. 



Total 

 Surface 



50 sq. in. 



78 sq. in. 



332 sq. in. 



From these figures it is evident why bluegrass is so effective in form- 

 ing turf and in preventing soil erosion. Further evidence of its copious 

 root system is obtained when a comparison is made of the roots of three 

 grasses growing in the field under similar conditions. An examination 

 of sample volumes of soil, 3 inches in diameter and 6 inches deep (42 

 cu. in.) showed that for each cubic inch of soil: 



Oats had 15 sq. in. of root surface and 150,000 root hairs. 



Winter rye grass had 30 sq. in. of root surface and 300,000 root hairs. 



Bluegrass had 65 sq. in. of root surface and 1,000,000 root hairs. 

 The roots of oats occupied 0.55 of 1 per cent of the soil volume; those of 

 winter rye grass 0.85 of 1 per cent; and those of bluegrass 2.8 per cent. 



REFERENCES 



Dittmer, H. J. A quantitative study of the roots of a winter rye plant. Amer. 

 Jour. Bot. 24:417-420. 1937. 



Dittmer, H. J. The efficiency of monocot roots in soil conservation. Univ. of 

 Iowa Nat. Hist. Studies. 17:343-346. 1938. 



Dittmer, H. J. Quantitative study of the subterranean members of three field 

 grasses. Amer. Jour. Bot. 25:654-657. 1938. 



Weaver, J. E. Root Development of Field Crops. McGraw-Hill Book Com- 

 pany, Inc. 1926. 



