90 
BULLETIN 1059, U. • S. DEPARTMENT OF AGRICULTURE. 
5. It is to be noted that the percentage of variation of individual 
eases is slightly less when the final (diagram 5) rather than the mean 
wilting coefficient of each soil is taken. On the other hand, there is 
considerably more spread between the two groups on this basis. It is 
believed that the slightly poorer showing made by using the mean 
wilting coefficient is due to the fact that losses caused primarily by 
fungi were not entirely eliminated from the calculations. With care 
in this respect, the mean value for all the seedlings is undoubtedly 
the more dependable and also more expressive. It should be noted 
in this connection that in a group of 100 seedlings the weakest usually 
DIAGRAM 5 
RELATION OF 
FINAL WILTING COEFFICIENT TO CAPILLARY MOISTURE 
SAME BASIS AS DIAGRAM 4 
12 
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give a wilting coefficient twice as high as that indicated by the final 
wilting, and not infrequently three times as high. 
6. The comparison of wilting coefficients with moisture equiva- 
lents shows a wide gap between the two groups. The value of the 
moisture equivalent data will be discussed later, 
7. While these results, all obtained at practically the same time 
and in soils which showed no great chemical activity, indicate a use- 
ful parallelism between wilting coefficient and capillary moisture, it 
should be pointed out that the wilting coefficient may occasionally 
go out of bounds as the result of acidity or alkalinity, so that any of 
the physical tests on soils, taken alone, are quite worthless. It should 
not be surprising to obtain wilting coefficients twice as great, relative 
to capillarity, as those indicated above, especially with the pines. 
