* . 
WHEAT PRODUCTION ON DRY LANDS. 31 
 Tasre 16.—Annual and average ytelds of wheat in the depth-of-plowing experiments at 
s ind, Wash., during the 4-year period from 1918 to 1921, inclusive. 
Annual and average yields per acre (bushels). 
Date and depth of plowing. 
1918 | 1919 1920 | 1921 | Average. 
o 
oO 
& 
for) 
. 5 
= 
& 
Ho bps He OO 
ry 
a a ra ee NL emis ale cH) se eel) 
wNoe “IW ~JInIs “JT Or Ord 
bt he 
PRIN! CRIN RE See Ook 
“101 © wwo srw on 
tae) 
ot 
by 
cS 
iv) 
ay 
fae) 
” 
. 
Dora Mou 
ee 
ho > bo “100 co © 0 orc ob 
SESS a OU COs an sania 
POAC! SB CO SORES COCO a 
CORN WHR CORR Crd COM 
is) 
© 
Ls) 
ay 
Jip 
oO 
e 
B 
mong 
WO oo m1 bo Or bo on oo 
al 
So. 
wwe 
| 
On the early plowing, except in 1921, yields usually have in- 
| creased with depth of plowing. This would tend to indicate that 
_ with better moisture conditions deep plowing is at least equal, if not 
superior, to shallow plowing. In the spring of 1920 the early plow- 
_ ing was delayed, and soil conditions at the date when it was actually 
done in reality corresponded to those at the usual midseason date, the 
results being similar. This delay was intentional in studying the 
influence of soil conditions on this factor. On the later dates nothing 
was gained by deeper plowing, indicating that under drier conditions 
and with the advance of the spring plowing season the average depth 
_ of plowing should be decreased. 
RESULTS AT NEPHi. 
The depth-of-plowing experiments at Nephi are divided into two 
parts. The purpose of the first section is to determine the effect 
of fall plowing to depths of 5 and 10 inches and subsoiling to depths 
of 15 and 18 inches on the yield of Turkey winter wheat. In sub- 
soiling, a furrow was first made with a plow and the plow immedi- 
ately followed by a subsoiler. Eight tenth-acre plats were used 
each year for these experiments, four being fallow and four produc- 
- ing a crop. 
_ Fall-plowed land often must be plowed again in the spring to kill 
weeds and volunteer growth. The second section of the depth-of- 
plowing experiment was started in 1916 for the purpose of determin- 
ing the proper depth of each, if both plowings were necessary. One 
lat was plowed 8 inches deep in the fall and 3 inches deep in the 
following spring; another was plowed 3 inches deep in the fall and 
8 inches in the spring; and the third was plowed 8 inches deep in 
_ both fall and spring. Six tenth-acre plats were used in this test, 
half of which were fallow each year while the other half were in 
crop. The results of both experiments are included in Table 17 
and part are shown graphically in Figure 16. 
