18 BULLETIN 1173, U. S. DEPARTMENT OF AGRICULTURE. 
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2 Diet a ead 
PLOWING. 
Of all tillage operations plowing is considered the most important 
and necessary. Very little experimental work has been done in | 
attempting to find out whether any other cultural operation, such 
as aidaae will take the place of plowing. For very light soils, a 
disking sufficiently thorough to keep the ground free from weeds 
occasionally may take the place of plowing, but no implement yet 
invented is as valuable as the plow for killing weeds and preparing 
an ideal seed bed. 
Of the controllable factors influencing yields of winter wheat, the 
time of plowing has been found to be one of the most important. 
Time of plowing also is of much importance to the dry farmer in 
the distribution of labor. Plowing for summer fallow may be 
done in the fall at any time after harvest until the ground freezes 
or at any time in the spring after the soil is dry enough. In many 
sections of eastern Oregon and Washington the harvesting of wheat 
is completed by August 15, while the ground does not often freeze 
before December 1. This allows a considerable period for fall 
plowing, both before and after the time for sowing winter wheat. 
Spring plowing, however, is generally practiced by farmers in the 
Columbia River and Great Basin areas. 
Experiments to determine the best time to plow as well as the best 
manner of plowing were carried on at each of the three stations, 
and the results are presented in this bulletin. Bey 
PLAN OF THE EXPERIMENTS AT MORO. 
In the experiments to determine the best date for spring plowing 
at Moro 60 tenth-acre plats were used, 30 being in crop and 30 in 
fallow each year. Of these plats 2 out of every 10 were check plats. 
One series of 10 plats was plowed on April 1, one on May 1, and one 
on June 1, except that the check plats in each series were plowed on 
April 1. Different methods of cultivating the summer fallow were 
employed on each of the plats in a series, except that all check 
plats were treated alike. 
For the fall-plowing experiments, 40 tenth-acre plats were used, 
20 being in crop and 20 left fallow each year. Eight plats were 
plowed early in the fall, when the ground was dry, 4 with a disk 
plow and 4 with a moldboard plow. Eight plats were plowed late 
in the fall, when the ground was wet, 4 with a disk and 4 with a 
moldboard plow. Beginning in the fall of 1919 all fall plowing was 
done with a moldboard plow. Two plats out of every 10 were 
check plats uniformly cultivated. During the first 5 years these 
were plowed late in the fall with a moldboard plow, but since then 
they have been plowed on April 1 with a moldboard plow, so as 
to have them uniform with the check plats in the experiments to 
determine the best date to plow in the spring. 
In all the date-of-plowing experiments Turkey winter wheat was 
used. The depth of plowing was from 7 to 8 inches in both spring 
and fall plowing. 
Depth-of-plowing experiments also have been conducted at Moro 
since 1912. In these experiments 40 tenth-acre plats were used, 20 
being cropped and 20 left fallow each year. One series of 10 plats was 
plowed from 8 to 10 inches deep and one series from 4 to 5 inches 
