44 



Journal of Agricultural Research 



Vol. Ill, No. I 



buffalo grass, western wheat-grass, brome-grass, and a Siberian wheat- 

 grass. Buffalo grass, brome-grass, and wheat-grass each gave two 

 crops, buffalo and grama mixed gave three cuttings, while western wheat- 

 grass produced but one cutting. The combined crops afford the best 

 basis for the comparison of these grasses. On the basis of the total dry 

 matter produced throughout the season, the water requirement is as 

 follows : 



Variety of grass Water requirement 



Buffalo 3o8±22 



Grama and buffalo 3891b 12 



Wheat-grass 7°S±27 



Brome-grass i,oi6±26 



Western wlieat-grass i, 076 ±29 



Brome-grass and western wheat-grass are comparatively very ineffi- 

 cient in the use of water, requiring from 22 to 29 per cent more water 

 than alfalfa. Western wheat-grass made a slow growth. Wheat-grass 

 is more efficient than alfalfa, requiring 15 per cent less water. The short 

 grasses made a wonderful showing, the water requirement of pure buffalo 

 grass being only about one-third that of alfalfa, and that of grama and 

 buffalo mixed, 47 per cent. The water requirement of buffalo grass is 

 only 8 per cent above millet, which is one of the most efficient of the 

 introduced plants. The mixed buffalo and grama grass required 36 per 

 cent more water than Kursk millet. These are the first of the native 

 plants to show any marked efficiency in the use of water, although some 

 of the weeds, as will be seen later, are also highly efficient. 



Table XXVII. — Water rcquiremeiil of native and introduced grasses at Akron, Colo.. 



in 1913 



Plant and period of growth. 



Pot 

 No. 



Dry matter. 



Water re- 

 quirement 



based on 

 dry matter. 



I9'.v 



Grama (Bouteloua gracilis) and buffalo grass 

 (Bulbilis dactyloides), mixed, first crop, Jxme 3 

 to July 19 



139 

 140 

 141 

 142 



143 

 144 



Grams. 



50- I 

 26. 9 

 31.8 



21. 9 



22. I 

 25- 3 



Mean. 



Grama and buffalo grass, mixed, second crop, 

 July 19 to Aug. 26 



139 

 140 

 141 

 142 

 143 

 L 144 



Mean. 



5 1- 7 

 35-4 

 38.8 



37- Q 

 41. 2 

 26. I 



Kilos. 



17.4 



10. 7 



12.4 



7-5 



Q.8 



8.6 



13- 2 

 15.6 

 14.4 

 16. I 

 9-7 



347 

 398 

 390 

 342 

 443 

 340 



377±ii 



350 



373 

 402 

 380 

 391 

 371 



395 ± 7 



