VJ/ 



Circular No. 563 



May 1940 • Washington, D. C. 



UNITED STATES DEPARTMENT OF AGRICULTURE 



Relation of the Depth to Which the Soil is 



Wet at Seeding Time to the Yield of 



Spring Wheat on the Great Plains 



By John S. Cole and O. R. Mathews, senior agronomists, Division 

 of Dry Land Agriculture, Bureau of Plant Industry 



CONTENTS 



Introduction 



Material for and methods of study- 

 Results at individual stations 



Assinniboine 



Williston 



Huntley 



Dickinson 



Mandan 



Hettinger 



Sheridan 



Belle Fourche 



Page 

 1 

 2 

 4 

 5 

 5 



Results at individual stations— Continued. 



Ardmore 



Scotts Bluff 



Archer 



North Platte 



Akron 



Amarillo 



Results at all stations 



Summary and conclusions. 



Page 



7 

 7 

 8 

 8 

 8 



Literature cited. ^ 14 



Appendix 14 



^ yy^^w ^ 



INTRODUCTION 



The control that may be exercised by the initial water content of 

 the soil over the yields of spring-sown small grains, of which wheat is 

 the typical representative, on the Great Plains is a question of the 

 utmost importance. If the water content of the soil at seeding time 

 is an indicator of the order of yield that may be expected, knowledge 

 of that condition may be used as a guide to practice, by which the 

 chances of seeding a crop with a high expectation of failure or unsat- 

 isfactory yield may be materially reduced and advantage may be 

 taken of favorable indications to seed normal or above-normal acreages. 



The studies and publications of Halls ted and Mathews (6), 1 Hallsted 

 (5), and Mathews and Brown (8) show the high degree of control 

 exercised over the yields of winter wheat in the southern and cen- 

 tral Great Plains by the depth to which the soil is wet at seeding 

 time. The latter is for practical purposes, under the soil and cli- 

 matic conditions obtaining in the Great Plains, a measure of the avail- 

 able water that is stored in the soil at the time of determination. 

 The simplification of this measure to a visual observation of the depth 

 of wet soil and the direct translation of that observation into two or 

 three categories of yield and chances of failure undoubtedly were 



1 Italic numbers in parentheses refer to Literature Cited, p. 14. 

 207105°— 40 1 



