WINTER WHEAT IN THE GREAT PLAINS ARBA. 5 
year, the average of the yearly yields appearing in the last column 
to the right. (See Tables V to XVIII.) 
As here presented, the treatment of the land is specified as early 
fall plowed, late fall plowed, subsoiled, listed, disked, green manured, 
and summer tilled. Under these headings are subdivisions to show 
the preceding crop. At the Judith Basin and Huntley stations, on 
account of the lateness of the harvest, the plats in the ‘‘Early fall 
plowed” and the ‘‘Late fall plowed” columns are plowed at the 
same time, the former deep, 8 inches, and the latter shallow, about 
4 inches. 
Where winter wheat follows winter wheat, the system has been 
that of continuous cropping. 
Early fall plowing is done as early as practicable after harvest and 
to a good depth, the standard being set at 8 inches. The ground 
after being plowed is given sufficient cultivation with the disk and 
harrow, if necessary, to form a good seed bed. On one plat which 
is continuously cropped to winter wheat at each station late fall 
plowing is shallow, only about 4 inches, and is given a minimum of 
cultivation. 
Subsoiling is done on Jand continuously cropped to winter wheat. 
The treatment of the plat that appears at some stations under this 
heading is the same as the treatment of the plat that appears under 
“arly fall plowed,” except that it is subsoiled. At the time of 
plowing, a subsoiler is run in each alternate furrow to an additional 
depth of 6 to 8 inches, making a total depth of about 14 inches. 
This usually is done two years in succession and then omitted for 
two years. 
The plat that appears at some stations under the heading “ Listed,” 
following winter wheat, is continuously cropped to winter wheat. 
After harvest this plat is furrowed out with the lister instead of 
being plowed. It is worked down level and the seed bed prepared 
without the use of the plow. 
The plats on disked corn ground are all in rotation with other 
crops. Both 3-year and 4-year rotations comprise this series. The 
other crops may be oats, barley, green manure, or potatoes. In 
some rotations summer tillage replaces one of the crops. 
Where winter wheat is grown after a green-manure crop, the sys- 
tem is that of a 4-year rotation in which there is a row crop and 
one of the small grains. In some of the 4-year rotations summer 
tillage is substituted for the second small-grain crop. Rye and 
field peas are used as green-manure crops. At Hays, Garden City, 
Dalhart, and Amarillo cowpeas were used instead of field peas 
during the first years. 
The method of summer tillage practiced is of an intensive type. 
The land lies fallow for a year. It is kept clear of weeds and as far 
as practicable a mulch is maintained on it during the summer pre- 
