SHERIDAN FIELD STATION, 1917 TO 1923 29 
lows killed back and many died each year until 1920. Those re- 
maining on the east side have since made a good growth with little 
killing back, but practically all of those on the west, except in the 
drainage course, died in 1921 and 1922 and were pulled out in the 
fall of 1922. This now leaves a strip of clean cultivated land about 
12 feet wide on the west side. 
Boxelders, except in the row farthest east, killed back badly in 
the winter and spring of 1921 and 1922, probably from drying winds 
and lack of moisture in the spring. Growth in the 4 by 4 block was 
shorter and killed slightly less than in the 4 by 8 block. Very little 
killing back was evident, however, in the box elder row with the 16- 
foot space between it and the next row. Chinese elm has made the 
fastest growth of any sort and has killed back but little. American 
elm has killed but little more, but growth has been slow. Ash has 
not killed back noticeably, but has grown very slowly. 
Evergreens of different species were planted each year in a row 16 
feet from the willows on the east side, but until the planting of 1922 
only a few lived through the smnmer. In 1922 the seedlings were 
shaded with shingles and most of them survived. 
Additional plantings were made in 1921 and 1922, which included 
Chinese elm, boxelder, ash, buffaloberry, Russian wild olive, and 
Siberian pea-tree. No killing back or dying out has been evident 
with these plantings. The spacing distances include 6 by 8 feet, 
8 by 8 feet, 8 by 12 feet, and 12 by 12 feet, making six different 
spacings now being tried for trees in the shelter belt. 
SUMMARY 
The results of work with crop rotations and tillage methods over 
a period of six years; with varieties of grain and forage crops, rates 
and dates of seeding grain crops, and methods of seeding forage crops 
over a 7-year period; experiments with potatoes; and shelter-belt in- 
vestigations are reported in this bulletin. 
The rainfall records and the seasonal variations in yield show the 
seasonal rainfall to be the chief controlling factor in crop production 
over this area, but attempts to overcome the controlling influence of 
rainfall by means of cultural practices have met with limited success. 
The investigations do not show any cropping method that may be 
depended upon to insure a good crop every year, but substantial 
differences are shown between different methods, and good average 
yields are obtained by the better practices. 
Material differences in yield between crops on fall plowing and 
those on spring plowing are shown in some years. Over a period of 
years, however, the average differences are too small to be of more 
than minor importance provided that seeding is not unduly delayed 
by the spring plowing. 
Yields of small grain on corn ground were slightly greater than on 
land in small grain the previous year. Yields of spring grain on 
corn ground averaged only slightly lower than on fallow. Raising 
grain crops on disked corn ground is one of the cheapest methods of 
production. The yields on disked corn ground are practically as 
great as on plowed corn ground. The feed value per acre of corn, 
including the stover, is as great as that of any of the grain crops. 
Consequent^, it appears that corn should have a definite place in 
any system of crop production for this area. 
