FACTORS AFFECTING YIELDS OF WINTER WHEAT GRAIN 
AND FORAGE IN THE SOUTHERN GREAT PLAINS * 
H. H. Finnell? 
During the war years of the forties, grazing of winter wheat became an important 
source of cash revenue to wheat farmers. Whether grazing reduced grain yield, and if so 
how much, was of interest to farmers. Some operators tried the practices of heavier 
rates and/or earlier dates of seeding than were common for grain production to increase 
pasturage. 
This study of data from pastured fields surveyed in cooperative research of the 
(U. S.) Soil Conservation Service and the State experiment stations of Colorado, Kansas, 
New Mexico, Oklahoma, and Texas has been made through the aid of Oklahoma Agricul- 
tural Experiment Station's Statistical Laboratory facilities. It consists of two approaches 
to the question of the effect of grazing on grain yield. The extent of possible grazing was 
judged by the yield of pasturage cut in the tests. Also, an analysis was made of other 
factors that might relate to pasturage and grain yield. 
The area of study consists of parts of the southern Great Plains where grazing of 
winter wheat was a common practice during the period of record, 1946-51. It includes 
the Panhandles of Oklahoma and Texas, anda few Soil Conservation Districts in the five 
States immediately adjoining the Panhandle High Plains. This area is part of the exten- 
sive ranching territory of the Southwest. 
EFFECT OF GRAZING ON GRAIN YIELD 
There were available 884 records of grazing winter wheat in 23 locations. Alto- 
gether, the first approach involved 51 time and place combinations for direct comparison 
of grazed and ungrazed grain yields. An average of all yields from grazed fields was en- 
tered against an average of an equal number of nearby fields that were not grazed, unless 
the grazed fields were in the majority, in which case all available records for grazed and 
ungrazed fields were used. 
Average grain yields of the 51 comparisons were 14.6 bushels per acre for grazed 
fields and 14.8 bushels per acre for ungrazed fields. 
The second approach was by correlation analysis. The variable in question, yield of 
forage dry matter removed per acre by grazing, was included in multiple correlation to 
grain yield with several other factors. The same group of factors was correlated also to 
forage yields. Standard partial regression coefficients were selected as the best measure 
of independent effect of each variable. Variables which showed a significant relation to 
either forage or grain yield through the standard partial regression coefficient are in- 
cluded in the tabulation (table 1). As to the effect of varying the amounts of forage dry 
matter removed per acre by grazing on grain yields, no significant relation was ob- 
served. (See first entry in table 1.) 
1 Contribution from the Agricultural Research Service and the Soil Conservation Service, U.S. D.A., and the Colorado, 
Kansas, New Mexico, Oklahoma, and Texas Agricultural Experiment Stations. Published with the approval of the Directors. 
Research Specialist, Western Soil and Water Management Research Branch, Soil and Water Conservation Research Division, 
Agricultural Research Service, U.S.D.A., and Assistant Director of Oklahoma Agricultural Experiment Station, Goodwell, Okla. 
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