SPRING WHEAT TX THE CHEAT PLAINS AREA. 39 
account for an increase of more than 1 bushel per acre. At Judith 
Basin the increase has been 1.9 bushels and at ScottsblufF 2.5 
bushels. This evidence from eight stations, some of which have 
records for study covering eight years, together with the evidence 
at hand but not here reported of other work on depth of plowing, 
which includes deep tilling and dynamiting, would seem to be con- 
clusive that the nature of the Plains and the trend of their agriculture 
arc not to be changed by the simple expedient of working them to a 
greater depth than is reached by the ordinary plow and equipment. 
Listing wheat stubble instead of plowing it in the fall has resulted 
in a small increase of yield at seven of the eight stations where it has 
been tried. At Amarillo it has increased the yields in the years of 
heaviest wheat production, but it shows on the average a loss of 0.6 
bushel per acre at this station. As it is a somewhat cheaper method 
of preparation than fall plowing, it has consequently been a more 
profitable one. 
Except at the Judith Basin and Akron stations, summer tillage 
has given the highest average yields of any method under trial. At 
Akron the yield on summer tillage has been exceeded by that on 
spring-plowed corn ground by 0.3 bushel per acre. The reason for 
the departure at the Judith Basin station from the general rule is 
discussed under that station. For the whole 14 stations under 
study the average increase in yield over disked corn ground has been 
3.1 bushels per acre. Summer tillage requires the use of the land 
two years to produce a crop and requires an extra amount of culti- 
vation to keep it free from weeds in the fallow year. It consequently 
has the highest acre cost of any method under trial except that of 
green manuring. A study of the relative profits and losses from 
different methods, as given in Table XIX, shows that the increase in 
cost of production by summer tillage has been relatively greater 
than the increase in yields resulting from it. With one or two 
exceptions the highest yields have been obtained by this method. 
It has not at any station been the most profitable when a profit was 
realized nor has it been the source of the least loss where wheat has 
been raised at a loss. At eight stations it shows a profit, but a smaller 
one than was realized from some other method or methods. At 
three other stations it has resulted in a loss while some other methods 
have resulted in profit. At the remaining three stations its practice 
has increased the loss attending the use of less expensive methods. 
Green manuring is the most expensive method under trial. It 
resembles a fallow in that it requires the use of the land for two years 
for the production of one harvested crop, with the added expense of 
seed and seeding. There is a saving in cultivation during the spring 
while the crop is growing, but this is offset by the necessity of plowing 
to turn the crop under and is not sufficient to make up for the cost 
