16 CULTIVATION METHODS AND ROTATIONS FOR GREAT PLAINS. 



methods of seeding were essentially the same for the respective 

 groups for all stations. The comparisons having been made between 

 groups at each station instead of between stations, the slight differ- 

 ences mentioned could in no possible way affect the conclusions. 



The accompanying tables give the yields in bushels per acre for 

 each one of the 216 plats. They also give differences in bushels per 

 acre between the "A," or continuously cropped ordinary-method 

 plats, and "B," or continuously cropped moisture-conservation plats; 

 and the or "D," alternately summer-tilled plats, respectively. 



The "A," or continuously cropped ordinary-method yields, are used 

 as a basis for all comparison. The three tables represent, respectively, 

 the three series — wheat, oats, and barley. The averages at the foot 

 of each table are the average yields per acre in bushels and the aver- 

 age difference in bushels per acre between the groups for each series, 

 respectively, for all of the 18 tests. 



Table I. — Comparison of yields to the acre of wheat series, by groups. 



Station. 



Judith Basin, Mont. . 

 Dickinson, N. Dak... 



Do 



Edgeley N. Dak 



Do 



Do 



Highmore, S. Dak. . . 



Do 



Bellefourche, S. Dak. 

 North Platte, Nebr.. 



Do 



Do 



Akron, Colo 



Hays, Kans 



Garden City, Kans... 



Dalhart, Tex 



Amarillo, Tex 



Do 



Year. 



Average. 



1907 

 1908 



1909 

 1907 

 1908 

 1909 

 1909 

 1908 

 1909 

 1909 

 1908 



Continuous cropping. 



Group A, 

 ordinary 

 methods. 



Group B, 

 conserva- 

 tion 

 methods. 



Bushe's. 

 33.0 

 24.3 

 26.8 

 4.1 

 13.3 

 28.3 

 28.8 

 26.3 

 23.8 

 24.5 

 22.7 

 23.0 

 14.3 

 1.2 

 2.1 

 .0 

 17.0 

 .0 



17. 49 



Bushels. 

 33.4 

 17.7 

 25.2 



7.0 

 15.3 

 23.3 

 29.7 

 19.7 

 23.3 

 26.0 

 27.3 

 15.3 

 10.3 



4.5 



3.2 

 .0 

 14.0 



2.8 



16.53 



Alternate 

 cropping, 

 Group C 

 or D, sum- 

 mer tillage. 



Bushels. 

 34.0 

 33.8 

 35.7 

 9.9 

 16.0 

 27.0 

 30.0 

 30 7 

 32.2 

 31.8 

 40.5 

 18.0 

 18.5 

 4.2 

 6.7 

 10.5 

 16.0 

 10.5 



22. 55 



Gain (4-) or 

 loss (-) by 

 conservation 

 over ordi- 

 nary meth- 

 ods, Group B 



compared 

 with Group A. 



Bushels. 

 +0.4 

 -6.6 

 -1.6 

 +2.9 

 +2.0 

 -5.0 

 + .9 

 -6.6 

 - 5 

 +1.5 

 +4.6 

 -7.7 

 -4.0 

 +3.3 

 +1.1 

 .0 

 -3.0 

 +2.8 



-0. 86 



Gain ( + ) or 

 loss ( — ) by 

 summer til- 

 lage over 

 ordinary 

 methods, 

 Group C or D 



compared 

 with Group A. 



187 



