UNITED STATES DEPARTMENT OF AGRICULTURE 
^»? BULLETIN No. 1004 
Washington, D. C. PROFESSIONAL PAPER March 31, 1923 
USE OF WATER BY SPRING WHEAT ON THE 
GREAT PLAINS. 
By John S. Cole, A^ronoinist, and O. R. Mathews, Assistant Agronomist in 
Dry-Land Agriculture, with an introduction by E. C. Chelcott, Agriculturist 
in Charge of the Office of Dry-Land Agriculture Investigations, Bureau of 
Plant Industry. 
CONTENTS. 
Page. 
Introduction 1 
Statement of the problem 2 
Source, character, and method of study of the data 3 
Daily rate of the use of water while the crop is growing rapidly 6 
Rate of the use of water as the soil moisture approaches depletion 11 
Rate of the use of water during the growing season 12 
Quantity of water used during the growing season 20 
Correlation between the use of water and the yield at individual stations 26 
General discussion of the results 30 
Conclusions 32 
INTRODUCTION. 
Since 1906 the Office of Dry-Land Agriculture Investigations has 
been conducting experinrients to determine the possibilities and best 
methods of crop production on the Great Plains. Coincident with 
this work and an integral part of it since 1907 has been the determi- 
nation of soil moisture in cooperation with the Biophysical Labora- 
tory of the Bureau of Plant Industry. The investigations have been 
continuous, coordinated, and systematic at 24 field stations/ care- 
fully located to be most representative of general as well as local 
conditions. 
^Miile the data from a single station or a single year are valuable 
in themselves, they are still more valuable in their contribution to 
the mass of facts accumulated. Covering a long series of years, em- 
bracing wide ranges of soils, climatic conditions, and crop adapta- 
tions found from the northern to the southern Plains and from the 
lowest to the highest altitudes within them, the mass of comparable 
data that have been gathered has a value that while foreseen affords 
possibilities of study that could hardly have been appreciated when 
^ The stations in Montana. North Dakota, Wyoming, Nebraska, and Kansas are con- 
ducted cooperatively Nvith the agricultural experiment stations of the respective States. 
The stations in South Dakota. Colorado, Oklahoma. Texas, and New Mexico are operated 
independently by the United States Department of Agriculture. 
21511°— 23 1 
