274 



Journal of Agricultural Research 



Vol. XVI. No. lo 



plants can reduce the soil moisture {I) , the point at which root penetration 

 practically ceases (7, p. 2yg), and the water-retaining capacity of well- 

 drained arable mineral soils {3, p. 6g), and such an expression as the 

 above makes all these relations apparent at a glance. The ratio may be 

 used alone to indicate the relative moistness, while its combination with 

 the hygroscopic coefficient expresses the moisture condition. 



Table IX. — Ratio of moisture content to hygroscopic coefficient at different levels on 



plots 2 and 4, in igi5 



The high ratios observed in the subsoil of these plots is probably due 

 to the retarding influence which the substratum of gravel and coarse 

 sand exerts upon the downward movement of water (j, p. 34-41). 



In a study somewhat similar to the one here reported, but made in 

 eastern Nebraska in 191 2, one of us (Alway) found a similar influence of 

 the organic matter upon the amount of useful moisture retained (4, p. 

 474) , but there the conditions were not so satisfactorily comparable, an 

 exposed subsoil poor in organic matter being compared with an adjacent 

 surface soil. 



MOISTURE RELATIONSHIPS AND PRODUCTIVITY IN LATER SEASONS 



Plot 3 showed itself far the more productive of the two plots in 191 5, 

 as had been the case also in such of the preceding 22 years of the experi- 

 ment, as the coincidence of the corn crop on plot 3 permitted a direct 

 comparison of yields (Table X). In 191 6 spring wheat was sown upon 

 all five plots and the yields were relatively unchanged. However, red 

 clover (Tri folium pratense) was seeded with the wheat and while the 

 stand of clover plants was even and moderately thick on all the plots, 

 it was especially fine on No. 4, and in the following year the yield of hay 

 was considerably the greater on this plot and the aftermath also was 



