12 BULLETIN 268, U. S. DEPARTMENT OF AGRICULTURE. 
Perhaps the first thing that impresses one in viewing the average 
yields from all stations is the much greater adaptation of oats to 
the northern than to the southern section of the Plains. There is an 
almost constant decrease in yields from the northern, cooler, shorter 
season stations to the southern, warmer, longer season ones. This 
decrease is about the same for the heavier yielding as it is for the 
lighter yielding methods. This decrease in yield from north to south 
for all methods proves that the problem is one of adaptation of crops 
to conditions rather than one that can be overcome by cultural prac- 
tices. 
General averages for all of the stations mean little, as differences in 
yield obtained at one station by the combination of factors that 
determine yield may be balanced by differences in an opposite direc- 
tion, as a result of a different combination of factors, at another 
station. With the trifling exception of a fraction of a bushel at 
Edgeley, spring plowing at all stations north of Hays has given higher 
average yields than fall plowing. At Hays and the stations south 
of it, fall plowing has been in about an equal degree better than spring 
plowing. The greater number of stations represented in the northern 
group makes the general average of averages show a small margin 
in favor of spring plowing. The general average, however, is of little 
value. It should not influence the practice at those stations whose 
results show fall plowing to be for them the best practice. 
At all of the stations north of North Platte, disking has been pro- 
ductive of higher average yields than either fall or spring plowing. 
At North Platte, Dalhart, and Amarillo, it has been between the two 
in yield. At Hays it has yielded the same as fall plowing and higher 
than spring plowing. At Garden City it has yielded higher than 
either. In the general average of all the stations reported it has 
given a yield of 28.3 bushels per acre against 25.8 bushels for spring 
plowing and 24.4 bushels for fall plowing. The great bulk of the 
land disked is corn ground. 
With the exception of a sharp decrease from subsoiling at Akron 
and a similar increase from listing at Garden City, the yields from 
each of these practices have not departed far from the yields of 
ordinary plowing. 
Green-manured land has been productive of higher yields than either 
fall or spring plowed or disked corn ground at 9 of the 13 stations 
from which results from it are reported. At Dickinson it has given 
lower yields than disked corn ground. At Hettinger, Akron, and 
Dalhart it has yielded less than any of the three methods mentioned. 
At Amarillo fall-plowed land has exceeded it in yield. 
Summer tillage has produced higher yields than any of the methods 
under trial at every station except Hettinger, where it has been ex- 
ceeded only by disking corn ground. Averaged for all the stations, 
