RELATION BETWEEN WEATHER CONDITIONS AND 
YIELD OF COTTON IN LOUISIANA 1 
By Bradford B. Smith 
Associate Statistician , Bureau of Agricultural Economics , United States Depart¬ 
ment of Agriculture 
INTRODUCTION 
This study was undertaken to discover 
to what degree the variations in yield 
of cotton may be explained on the basis 
of the available weather data. Obvi¬ 
ously the yield of cotton must be 
greatly influenced by factors which 
operate prior to our being aware of 
their effect as measured by the resulting 
yield. If we may measure these factors 
as they occur, and then discover a statis¬ 
tical relation between the antecedent 
conditions and the subsequent yields, 
we are then in position to make fore¬ 
casts of yield at the time the weather 
conditions occur. In the following dis¬ 
cussion it will be shown that a fairly 
close relationship was established be¬ 
tween the weather conditions prior to 
September and the subsequent final 
yield of cotton. The nature of these 
functional relations is shown in Figure 1. 
Analyses of the quantitative relation¬ 
ship between weather factors and yields 
of crops have been made by several in¬ 
vestigators. For example, H. L. Moore 
in 1917, 2 and more recently J. Warren 
Smith, of the United States Weather 
Bureau, 3 have both published results 
of such investigations. The present 
contribution is an extension of the 
methods suggested in Moore's book. 
A statement follows of the theoretical 
considerations upon which the subse¬ 
quent statistical analysis was made. 
FACTORS INFLUENCING YIELD 
There are four major types of factors 
influencing yield: (1) Inherent capac¬ 
ity of the plant itself to bear; (2) fer¬ 
tility of the soil; (3) weather and length 
of the growing season; and (4) cultural 
methods applied to the crop during its 
growth; that is, the influence which 
the grower can exert to accentuate 
favorable, and minimize unfavorable, 
natural conditions. 
If a State is considered as a whole, 
the influence of some of these factors, 
while continuing to be of significance 
in determining the long-time or trend 
movement in yield, is of little signifi¬ 
cance in year-to-year variations. There 
is great inertia in the cultural habits of 
the producer, for example. A new 
method when introduced is adopted 
and tried by a few, and if successful it 
is taken up by others the following 
season. Such a slow change is wit¬ 
nessed in the gradual introduction of 
the practice of spacing plants closely 
in the row—from 4 to 8 inchq^—a 
practice that is recommended by the 
United States Department of Agricul¬ 
ture as a means of reducing losses from 
weevil. The effects of such changes, 
even if marked in given localities, are 
but slight when the State is considered 
as a whole and the total effect on yield 
is so spread over a number of years 
that it may be considered as a long¬ 
time or “trend” change and conversely 
of little importance in year-to-year 
variations. 
A similar proposition holds true for 
seed introduction. The shifting from 
one staple length to another in accord¬ 
ance with the premiums offered for 
long staple cotton will, however, prob¬ 
ably find some reflection in yield, since 
a normal yield in pounds per acre for 
short staple is considerably greater 
than for long staple. Consequently, 
variations in yield not accounted for 
by weather may be considered in some 
degree attributable to this factor. 
Soil fertility of the areas in cotton 
may be changed by the shifting of 
acreages, the opening up of new lands, 
and gradual exhaustion of the soil. 
The producer may also apply various 
kinds and amounts of fertilizer ac¬ 
cording to his cultural practice. A 
glance at Figure 1 will show that 
there is a distinct downward trend in 
yield. The bringing in of new lands 
less suitable for cotton growing may 
in part explain this trend, but it is 
more probable that the Mexican boll 
weevil has more to do with it. As in 
1 Received for publication Sept. 15, 1924; issued August, 1925. 
2 Moore, H. L. forecasting the yield and the price of cotton. 173 p., illus. New York. 1917. 
s Smith, J. W. influence of the weather on the yield of crops. Mo. Weather Rev. 50: 567-572, 
illus. 1922. 
Journal of Agricultural Research, 
Washington, D. C. 
(1083) 
Vol. XXX, No. 11 
June 1, 1925 
Key No. N-l 
