TILLAGE AND ROTATION EXPERIMENTS AT NEPHI, UTAH. 
15 
The yields obtained in this test, as shown in Table V, agree with 
the moisture content of the plats, as previously discussed. The 
highest average yield was obtained from the plats plowed 10 inches 
deep, and the lowest average yield was obtained from the plats 
subsoilcd 18 inches deep, while the plats plowed 5 inches deep gave 
better yields than those subsoiled 15 inches deep. The widest 
difference in the yields, however, is not significant. The point most 
strongly emphasized by the results is that there was no material 
difference in the yields obtained from plats plowed at depths varying 
from 5 to 18 inches. 
RELATIVE COST OP PLOWING AND SUBSOILING. 
Since there was no material difference in the moisture content or 
in the yields of the plats included in the depth-of-plowing tests, it is 
SUBSO/LED /3'DEEP 
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SVBSO/IEP /S "DEEP. 
PLOWED /O'DEEP 
PLOWED S DEEP. 
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3 
4 
4 
6 
Fig. 7.— Graphs showing the average seasonal decline in percentage of moisture in each of the upper 
6 feet of soil, as found in the fall depth-of-plowing tests at the Nephi substation, 1909 to 1913, 
inclusive. 
well to consider the cost of crop production on the plats to determine, 
if possible, the comparative value of each operation. The subsoiled 
plats were first plowed and then subsoiled, the subsoiler following in 
the plow furrow. The draft of the subsoiler was as great as that of 
the plow ; hence, the subsoiling entailed twice the expense of plowing 
and did not increase the yield of the plat. For this reason there was 
nothing in favor of and much against subsoiling as tested at Nephi. 
There was so little difference between the yields of the two plowed 
plats that it is difficult to see any advantage in favor of deep plowing 
over shallow plowing. In fact, when considered from the standpoint 
of net returns, there was no advantage for deep plowing, because of 
the greater expense incurred. The most evident point in favor of 
deep plowing seems to be, as previously noted, that it covers the 
stubble better and this obviates some trouble at seeding time. Had 
some plats been plowed at different depths between 5 and 10 
inches and some others plowed at these same depths in the spring 
as well as in the fall, it is possible that some more significant data 
