12 BULLETIN 991. TJ. S. DEPARTMENT OF AGRICULTURE. 
lowing oats 15.7 bushels per acre. In the other nine years the fallow 
averaged 14.2 bushels, and the oat stubble 13.4 bushels. The 13-year 
average is 17.S bushels on fallow and 11.1 bushels following oats, a 
difference of 3.7 bushels in favor of the fallow. 
The average yield of oats on fallow in rotation No. 5 has been 36 
bushels, and on fall-plowed wheat stubble in rotation Xo. 5. 35.2 
bushels per acre. The higher yield has been on fallow seven years 
and on the wheat land six years. 
Other opportunities for comparisons are offered in the continuous 
cropping series. In this series each crop — wheat, oats, barley, and 
corn — occupies four plats. Plat A bears the same crop continuously. 
the preparation being shallow spring plowing. Plat B is continu- 
ously cropped under a system of deep (8-inch) fall plowing. Plats 
C and D are alternately cropped and fallowed, plat C being in crop in 
the even years and plat D in the odd years. 
The wheat on fallow has averaged 1.1 bushels more than on spring 
plowing and 3 bushels more than on fall plowing. In 9 of the 13 
years under study the yield on fallow has been higher than on either 
of the other plats. In the duplication of these plats on section 9 for 
the three years 1917 to 1919. inclusive, the yield on fallow has been 
6.1 bushels more than on spring plowing and 8.1 bushels more than on 
fall plowing. 
Oats in this series show a stronger response to fallow than wheat. 
or than oats did in rotation Xo. S as compared with rotation No. 5. 
Xot only is the yield on fallow a little higher, but the yields of oats 
in continuous cropping with which it is compared are much lower 
than those in rotations. The yield on fallow in this series is 4D.3 
bushels: on spring-plowed oat stubble. 25.2 bushels: and on fall- 
plowed oat stubble, 23.7 bushels. The increase in favor of fallow 
in this case is 15.^ bushels over the average of the two other methods. 
In the same series barley on fallow has yielded 19.8 bushels : on 
spring-plowed barley stubble. 17. S bushels: and on fall-plowed 
barley stubble. 15.1 bushels. The increase due to fallow is 2 bushels 
over spring plowing, and 1.1 bushels over fall plowing, or 3.1 bushels 
over the average of the two. 
With corn, there is practically no difference in the average yields 
of the different plats in this series, although there have been some 
years strongly in favor of and some as strongly against fallow. The 
corn plats are duplicated on section 9. and there also no difference 
in yield is observed. 
CORN GROUND COMPARED WITH FALLOW AS A PREPARATION 
FOR SMALL GRAINS. 
The experiments offer a number of direct comparisons of fallow 
and corn ground as preparations for wheat and oats. Potation Xo. 5 
is fallow, wheat, and oats, and rotation Xo. 3 is corn, wheat, and oats. 
The heavier yield of wheat has been on the corn ground seven years 
and on the fallow six years. The fallow has had somewhat the 
heavier vield of straw, but the srrain has averao-ed onlv three-tenths 
