29 ° 
Journal of Agricultural Research 
Vol. I. No. 4 
properties or composition of the crop. If the adjacent data in Table I 
under each locality are similar and distinctly unlike the corresponding 
group in another region, it is evident that the locality—that is, the cli¬ 
mate—has exerted a strong influence. Likewise, if a similarity exists in the 
data in the adjacent columns in Table II as regards crops from the same 
soil and there is a distinct difference between them and the corresponding 
data from other soils, it is clear that the soils in themselves have a deter¬ 
mining influence, regardless of the locality in which the soils happen to be. 
To avoid erroneous conclusions concerning any property or constituent, 
due to accidental differences occurring in individual groups of data, it is 
necessary to make a survey of all the data on hand regarding that prop¬ 
erty or constituent. In a measure the averages drawn from the several 
groups of data furnish quantitative values which may indicate the per¬ 
sistence or the nonpersistence of such differences. The average diver¬ 
gences from these means, together with the minima and the maxima, 
supply further quantitative evidence along this line. Such averages 
and the corresponding minima and maxima are brought together in 
Tables III, IV, and V. 
This experiment, covering a period of four years, in which three fairly 
good wheat soils, one each from California, Kansas, and Maryland, were 
put down side by side in each of these three localities and cropped with 
the same variety of wheat, shows that the soil does not exert the chief 
or preponderating influence in determining the physical properties or the 
chemical constituents of the grain crop. No attempt has been made to 
trace out from these experiments the manner in which the climatic factors 
thus exert the chief determining influence on the composition of the 
wheat crop. The following possibilities may, however, be considered: 
(1) Differences in humidity may cause a difference in the transpiration 
of the plants, which in turn may react on the composition of the crop. 
(2) Variations in the amount and distribution of sunlight may influence 
diversely the photosynthesis of the plants. 
(3) Differences in temperature and in the succession of hot and cold 
periods may cause varying vegetative activities in the plants. 
(4) The climatic differences, such as the humidity, rainfall, temper¬ 
ature, and sunlight, may bring about changes in the physical, chem¬ 
ical, or biological characteristics of the soil which in turn may react on 
the crop. 
From this it should not be assumed that it is impossible for soil which 
has been transferred from one locality to another to become so changed 
by climatic environment that the character of the wheat grown thereon 
would be approximately the same as that grown in soil belonging to 
the second locality. This has been suggested to explain the facts ob¬ 
served during this experiment—namely, that wheats grown on the three 
soils in Kansas are very different from the same variety of wheat grown 
