820 
Yol. XXX, Xo. 9 
Journal of Agricultural Research 
Harris and Yao (IS). state that 
“ moisture samples taken from the 
Nephi substation to a depth of six feet 
prove in every case that fall plowing 
preserves more moisture than spring 
plowing/’ a statement rather difficult 
to understand in the light of the state¬ 
ments of Cardon (11) and Harris and 
Jones (16). 
Cates and Cox (12), basing their 
conclusions on data secured in studies 
at widely separated points over the 
entire United States, conclude that 
weed removal is the most important 
function of cultivation in handling the 
corn crop, and that the amount of 
moisture saved by such cultivation is 
negligible beyond a possible slight 
checking of run-off from heavy rains. 
Fortier (13, 14) shows that mulching 
a soil after irrigation conserves moisture, 
and that the deeper the mulch up to 
9 inches, the deepest used in his experi¬ 
ments, the more efficient the retention. 
At Wenatchee, Wash. (14), in a 21-day 
period during June, 1908, an unmulched 
soil lost 14.38 per cent, one with a 3-inch 
mulch, 3.98 per cent, one with a 6-inch 
mulch, 2.10 per cent, and one with a 
9-inch mulch, 1.06 per cent of the 
water applied in a 6-inch irrigation. 
Willard and Humbert (25) show a 
similar result. 
Harris and Bracken (15), from data 
secured under irrigation, state that 
cultivation is slightly more efficient in 
saving moisture than is no cultivation 
with weeds removed by pulling. They 
state that a comparison of deeply 
cultivated plats with those given shal¬ 
low cultivation or no cultivation shows 
a decided advantage for the latter in 
moisture content at the lower soil 
depths. 
McCall and Holtz (19) show that 
soils mulched during the period when 
moisture absorption was most active 
contained less moisture at the end of 
the fallow period than did other soils 
not mulched during the same absorp¬ 
tion period. They conclude that the 
mulch probably aids in retaining mois¬ 
ture already in the soil. 
Mathews (20), in reporting on the 
storage of moisture and its utilization 
by spring wheat, states that, as an 
average for all stations of the Office of 
Dry-Land Agriculture Investigations, 
Bureau of Plant Industry, United 
States Department of Agriculture, 
there are no notable differences in the 
moisture conserved by two continu¬ 
ously cropped plats, the one being fall 
plowed and the other spring plowed. 
He mentions certain seasonal condi¬ 
tions that may favor the first in the 
southern Great Plains, and the second, 
to the north, but that there are no 
consistent advantages in either case. 
Shutt (23), in Canada, reports that 
a packed fallow contained more mois¬ 
ture than one not packed. This in¬ 
dicates either superior absorption or 
superior retention on the part of the 
firmly packed soil, although which is 
the more likely hypothesis is not 
suggested by the author. 
From the foregoing it is clear that 
all investigators have not arrived at 
the same conclusion. It is equally 
clear that all are not measuring the 
mulch from the same point of view. 
In the conservation of natural precipi¬ 
tation the mulch must be considered 
both in its effect on absorption and its 
effect on retention. Where the mulch 
is measured solely as a retentive agent, 
as under irrigation, the evidence is 
unanimous that its effect is positive 
in saving moisture. In measuring 
the value of the mulch in relation to 
natural precipitation, where both con¬ 
siderations come into play, the result 
is less clear and the advantages, if any, 
are slight, neutral, or negative. 
INVESTIGATIONS 
Soil-moisture problems are a very 
important part of the program of the 
Adams Branch Station of the Wash¬ 
ington Agricultural Experiment Station 
at Lind, Wash. Production in the 
territory this station serves is based 
on the summer-fallow system of alter¬ 
nate years of crop and fallow. One of 
the objects of the fallow is to conserve 
moisture and to carry it from one 
season to the next. As one of the 
factors affecting moisture conservation, 
the soil mulch has been studied during 
the six years 1918 to 1923, inclusive. 
Under field conditions it is often 
difficult to differentiate between the 
two different relationships of the 
mulch. This is particularly true when 
the period of greatest precipitation is 
concurrent with that of greatest evap¬ 
oration, as, for instance, in the Great 
Plains area. Climatic conditions on 
the Adams Station, however, meet 
the requirements for differentiation to 
a considerable degree. The distribu¬ 
tion of rainfall, and the seasonal fluctu¬ 
ation of temperature and relative 
humidity (figs. 1, 2, and 3), divide the 
year into distinct periods, during any 
one of which either absorption or 
retention becomes most prominent. 
During the late fall, winter, and early 
spring, when a good proportion of a 11 
precipitation occurs, relative humidity 
is comparatively high and absorption 
is the most important consideration. 
During the summer temperatures are 
