40 BULLETIN 214, U. S. DEPARTMENT OF AGRICULTURE. 
of seed and seeding. Yields have not been commensurate with the 
increased cost of producing them. At no station have the average 
yields following any green manure exceeded those from summer 
tillage. At Huntley and Dickinson, the two stations having the 
highest average yields, small profits have been realized from this 
method in spite of its high cost. At the 10 other stations at which 
it has been under trial the result has been a monetary loss, both 
actually and in comparison with other methods. 
It is hardly fair to charge the whole expense of green manuring to 
the one crop that immediately follows it, as is here done. It should 
have a cumulative effect in building up the soil or remedying its 
deficiency in organic matter. The available evidence is that on 
normal soils in the Great Plains, at least in the first years of the 
work, little effect is shown on other than the first crop. This effect 
is that of a fallow to the extent that the green manure approaches a 
fallow in the storage of water during the period after the crop is 
plowed under. 
At different times and in different sections certain methods have 
been exploited as the solution of the problems of dry farming. Each 
of these systems may have merit, but any and all fall far short of a 
panacea under all conditions. The observations and investigations 
that have developed these systems, or upon which the advocacy of 
special methods have been founded, have been altogether too lim- 
ited both in geographic extent and in range of time. There is 
always, too, the temptation to magnify the importance of those 
single years which may be exceptional, but whose results point 
strongly in the desired direction, losing sight of the fact that it is the 
average of a long series of years upon which the agricultural organi- 
zation and practices of a section are and must be based. 
The scope of the work in hand is broad enough, both in length of 
time and in geographic distribution, to overcome these objections. 
One fact conclusively shown is that cultivation is not an unfailing 
solution of the problem of drought. It will doubtless alleviate it to 
some extent, but can never fully overcome it. Some methods have 
shown consistent merit under some soil conditions. The same sys- 
tem when transplanted to some other environment may show little 
or no merit. With the exception of one year at one station the 
greatest difference in yield between the supposedly good and the sup- 
posedly poor method has been in the good years rather than the bad 
years. This shows that good systems have more efficacy in augment- 
ing the results obtained in a good year than in overcoming the con- 
ditions of a very unfavorable year. 
A study of the data given in the tables will show that at some 
stations no material difference has resulted from the various methods 
of tillage used in preparing the soil for spring wheat. 
