14 



LITERATURE CITED 



(1) Bell, M. A. 



1937. THE EFFECT OF TILLAGE METHOD, CROP SEQUENCE, AND DATE OF 



SEEDING UPON THE YIELD AND QUALITY OF CEREALS AND OTHER 

 CROPS GROWN UNDER DRY-LAND CONDITIONS IN NORTH CENTRAL 



Montana. Mont. Agr. Expt. Sta. Bui. 336, 123 pp., illus. 



(2) Cole, John S. 



1938. CORRELATIONS between annual precipitation and the yield of 



spring wheat in the great plains. U. S. Dept. Agr. Tech. 

 Bui. 636, 40 pp., illus. 



(3) and Mathews, O. R. 



1923. USE OF WATER BY SPRING WHEAT ON THE GREAT PLAINS. U. S. Dept. 



Agr. Dept. Bui. 1004, 34 pp., illus. 



(4) • — ■ and Mathews, O. R. 



1939. SUBSOIL MOISTURE UNDER SEMIARID CONDITIONS. U. S. Dept. Agr. 



Tech. Bui. 637, 71 pp., illus. 



(5) Hallsted, A. L. 



1937. REDUCING THE RISK IN WHEAT FARMING IN WESTERN KANSAS. KanS. 



State Bd. Agr. Bien. Rpt. (1935-36) 30: 98-111, illus. 



(6) and Mathews, O. R. 



1936. soil moisture and winter wheat with suggestions on abandon- 

 ment. Kans. Agr. Expt. Sta. Bui. 273, 46 pp., illus. 



(7) Mathews, O. R., and Barnes, B. F. 



1940. DRY-LAND CROPS AT THE DALHART, TEXAS, FIELD STATION. U. S. 



Dept. Agr. Cir. 564. (In press.) 



(8) and Brown, Lindsey A. 



1938. WINTER WHEAT AND SORGHUM PRODUCTION IN THE SOUTHERN GREAT 



plains under limited rainfall. U. S. Dept. Agr. Cir. 477, 60 pp. 

 (9) Thysell, J. C. 



1938. CONSERVATION AND USE OF SOIL MOISTURE AT MANDAN, N. DAK. 



U. S. Dept. Agr. Tech. Bui. 617, 40 pp., illus. 



APPENDIX 



Table 3. — Annual and average yields of spring wheat by each of three methods when 

 the soil was wet to different depths in the spring at 15 field stations in the Great 

 Plains during the period 1907-88 



ASSLNNIBOINE STATION, HAVRE, MONT. 



Year 



Plot A 



PlotB 



Plots C and D 



lfoot 



2 feet 



3 feet 



1 foot 



2 feet 



3 feet 



lfoot 



2 feet 



3 feet 



1916 



Bushels 



Bushels 

 45.8 

 3.5 



Bushels 



Bushels 



Bushels 

 47.5 

 3.8 



4.7 



Bushels 



Bushels 



Bushels 

 49.3 



Bushels 



1917 













11.7 



1918 





5.7 



"""To" 



7.5 

 6.7 

 









5.8 



1919 . 





1.5 







2.2 

 10.5 



19.0 





1920 



7.2 











1921 



9.7 

 7.2 

 16.7 

 11.8 

 16.3 













1922 











12.2 



1923- 





16.2 







20.0 





1924 







7.3 







19.0 



1925.. 





18.7 









18.5 



1926 





4.3 

 26.2 





1.7 

 30.7 







13.5 



1927... . . 















37.7 



1928 _ . 





16.0 



8.3 

 2.2 



13.0 









41.3 



1929 . 





7.3 









15.7 



1930 







1,5 













11.3 



1931 . 



.8 

 21.7 



.8 









3.0 

 27.2 





1932-. . . 







26.2 



.7 

 3.0 









1933 













12.8 



1935 ._.. 



4.2 

 













13.2 



1936 







.2 



5.0 



10.3 









.3 



1937 



1.2 







5.5 







1938 



13.2 









22.7 

















Average .... 



6.3 



11.2 



12.1 



4.8 



14.2 



16.2 



5.5 



19.2 



16.4 







Number of years 



5 



14 



3 



11 



9 



2 



1 



8 



13 



