736 
Journal of Agricultural Research 
Vol. XXIII, No. 9 
the soil. This, indubitably, has a tendency to shut off the air from the 
roots, which is essential to their proper growth. As it is, they can not 
penetrate deeply, which seems to be the main causes for their growth's 
being stunted. 
Secondly, cultivation cuts off the root hairs; thus the normal function 
of the tap root is much handicapped. Frequent cultivation, once or twice 
a week, does not give the tap root enough time to build up its new root 
hairs. 
Thirdly, frequent cultivation renders the soil too loose, thereby break¬ 
ing up the contact of the roots with the soil. Since the difference between 
the soil surface and water is only 15 inches, and the soil, being partially 
saturated, is already loose enough to induce a favorable root expansion, 
constant stirring of the soil simply destroys the necessary degree of com¬ 
pactness around the root. 
Under field conditions in the dry-farming regions where the precipita¬ 
tion is not over 20 inches annually, there is no chance of ever saturating 
the soil for any length of time. Cultivation or mulching can be recom¬ 
mended only where water becomes the limiting factor to crop growth. 
If there is enough precipitation to warrant a good and vigorous growth, 
or if the water table is near the surface, cultivation or mulching may be 
entirely out of place. 
Table VII.— Evapo-transpiration ratio of radishes as affected by mulching and culti¬ 
vation 
Evapo-transpiration. 
Weight of radishes. 
Evapo- 
trans- 
Treatment. 
Total. 
piration 
ratio 
(parts of 
Germi¬ 
nation. 
stage. 
Seed¬ 
ling 
stage. 
Root 
stage. 
Inches. 
Kgm. 
equiva¬ 
lent. 
Tops. 
Roots. 
Total. 
water to 
x part of 
radishes 
hy 
weight). 
No mulch. 
Inches. 
3.629 
3 - 5 26 
2. 771 
2 -S 38 
Inches. 
4. 212 
3 - 654 
3- 623 
2. 988 
Inches. 
5. 292 
3-895 
3 - 415 
3 - 793 
13 - *33 
11. 075 
9.809 
9 - 3*9 
99- 349 
83- 777 
74.207 
70.526 
Kgm. 
O. 0251 
.0205 
. 0160 
. 0187 
Kgm. 
O. 0733 
• 0384 
. 0168 
. 0488 
Kgm. 
O. 0984 
.0589 
.0328 
.0675 
1, 009 
1,422 
2, 262 
L 045 
Cultivation once a week 
Cultivation twice a week 
i-inch straw mulch. 
SOIL MOISTURE AS AFFECTED BY TIME OF CULTIVATION 
The question of spring or fall plowing has been one of the dry-farming 
problems. Opinions seem to differ. An experiment was carried out on 
the Nephi substation on -j^-acre plots to determine the moisture content 
of the soil by spring and fall plowing and by the different depths of 
cultivation. 
Table VIII.— Average soil moisture percentages to the depth of 6 feet with weeds pulled 
and the different depths of cultivation under spring and fail plowing 
Spring 
plowing. 
FaU plow¬ 
ing. 
Weeds pulled... 
18.7 
19.4 
20.4 
19.4 
20.2 
20.5 
21.4 
20.0 
2-inch cultivation. 
4-inch cultivation... 
fi-inch cultivation ... 
