73& 
Journal of Agricultural Research 
Vol. xxm, No. 9 
Table IX .—Average moisture percentages to the depth of 6 feet, showing the movement 
of water under mulches 
Middle of 
plot. 
43 feet from 
middle. 
46 feet from 
middle. 
Unmtilched 
land. 
Fall-plowed, straw mulch 4 inches.... 
24.7 
21.4 
21.4 
23.0 
21.7 
21.2 
I9.4 
21.-0 
21.0 
19.4 
Fall-plowed, earth mulch 4 inches. 
21.4 
21.4 
Spring-plowed, earth mulch 4 inches. 
The highest moisture percentages are found in the middle of the plots. 
Moisture percentages of the soil decrease as they approach the unmulched 
land, and the lowest are found in the unmulched land. If there is no move- 
PERCENTAGE OF MOISTURE 
W«DS CLINCH ♦INCH 4 INCH 
PUUJED COi.TlVA.TlON Court VACTIOH CvtflVATtON 
3 VO 3 VO 3 VO 3 VO 
lFt.H 
ZTt.- 
4-Ft.—I 
B 
r 
W////////J 
L 
1 
’////urn 
h 
1 
W//////A 
f- 
1 
/////////> 
f" 
1 
W/////L 
1 
■ 
1 
'///✓//// 
H 
1 
J 
b 
*- 
,., ariuuA 
a.wci> mnnmm 
Fig. 5. Diagram showing the retention of soil moisture as influenced, by clean culture and the different 
depths of cultivation to the depth of 6 feet in the fall-plowed and spring-plowed plots. 
ment of water, then there should be the same amount of water anywhere 
under a uniform mulch. The fact that there is more moisture in the 
middle of the plots and less moisture as it approaches the adjoining 
unmulched land shows plainly that water moves out from the mulched 
plots to the unmulched land. Under laboratory conditions, where side 
leaching and deep percolation of water can be controlled, the effectiveness 
of mulching can be determined easily. But under the field conditions, 
the same factors can not be controlled.' Whatever water may be saved 
by\ mulching may be lost through either of the foregoing processes. Thus 
it is not uncommon to find that a mulched plot may not have any more 
moisture than the unmulched, or that a thicker mulch may not be so 
effective as a thinner one. As shown in Table VIII, the 6-inch cultiva¬ 
tion, either spring-plowed or fall-plowed, is not so efficient as the 4-inch. 
It is very probable that when the mulch is kept too thick, light rainfalls 
