Ee BULLETIN 1173, U. S. DEPARTMENT OF AGRICULTURE. 
TILLAGE EXPERIMENTS. 
TREATMENT OF LAND BEFORE PLOWING. 
All the land at the stations at Moro and Lind was in crop at the 
time these stations were established. No experiments, therefore, 
have been conducted at either station on the best methods of pre- 
paring sod ground for wheat. At Nephi the station was located on 
virgin land. 
After removing a grain crop the farmer may do one of several. 
things to his fields. He may (1) disk the stubble land in the fall, 
(2) burn the stubble in the fall or spring, (3) plow the land in the fal}, 
(4) leave the stubble standing during the winter and disk the land in 
the spring, or (5) leave the land uncultivated until it is plowed in the 
spring. ach of these practices is followed by farmers in Oregon, 
Washington, Idaho,-and Utah. Plowing for fallow usually is done 
in the spring by most farmers in these States. 
FALL DISKING. 
Experiments have been conducted at each of the three stations to 
determine the value of fall disking when the land is to be spring plowed. 
These results are summarized in Table 6 and are shown graphically 
in Figure 10. The acre yields reported in this table are based-on 
yields of single tenth-acre plats at each of the three stations. 
+ a 
TABLE 6.—Annual and average yields of Turkey winter wheat on land disked in the fall 
and plowed early in the following spring for fallow and on land plowed in the spring 
but not disked in the fall, at Moro, Oreg., Lind, Wash., and Nephi, Utah, in varying 
periods from 1913 to 1921. 
Yield per acre (bushe!s). 
Station and treatment. | | 
1913 | 1914 | 1915 1916 | 1917 | 1918 | 1919 | 1920 | 1921 4 
mean 
Moro, Oreg.: | 
: Se Disked inthe fall... 3-1 7). eet | 23.0 | 25.6 | 23.6.7 34.3 | 21.2 | 17.3 | 38.3} 25.0 | 36.5] 27.2 
Not disked in the fall............... | 25.1 | 26.9 | 26.3 | 41.3 | 25.0 | 22.3 | 38.5] 29.7] 31.3] 29.6 
Lind, Wash.: 
Wisked in theta 2.) beeen RE eerie eins Sor 5.6 | 12.2] 83/123] 9.6 
Not disked in the fall. ..........---.|-.---- fe ke Reeceel Rez. Sas 6.2|12.3| 98] 15.7} 11.0 
Nephi, Utah: 
Disked in the fall ->..-. 42.48). the ieee 16.0 | 24.7 | 11.2 | 17.3 | 28.0 | 36.9| 223 
Not disked in the fall. .........----.|------ FESS (ere ae | 18.3.) 31.8 14.5 | 23.7 | 27.5 | 38.4 |e 
| 
Advantages claimed for fall disking are: (1) It kills weeds that may 
take out moisture after harvest, (2) it permits better penetration of 
the autumn and winter precipitation by mellowing the surface soil, 
(3) it covers weed seeds and shattered grain so that they germinate 
more quickly, (4) it prevents run-off in the early spring, and (5) it 
hastens the decay of the stubble and other vegetation. 
Experiments at the three stations have proved that these advan- 
tages are apparent rather than real. Table 6 shows that fall disking 
actually reduced yields at Moro, Nepbi, and Lind. Double disking 
ordinarily will not kill Russian thistle, one of the troublesome weeds 
which grows on wheat land after harvest. The moisture determina- 
tions at these stations also have shown that disking the stubble land 
