12 
BULLETIN 881, U. S. DEPARTMENT OF AGKICULTURE. 
where manure was used it was applied directly preceding the beet 
crop in three of the four cases, while in the alfalfa rotations one or 
two other crops occur between the alfalfa and the beet crops. There 
were four rotation pairs in the manure experiments previously de- 
scribed, 1 covering a 6-year period, 1912 to 1917. A summary of 
those results,- together with the results given in the preceding para- 
graphs, is presented in Table V. These comparisons show that the 
period of alfalfa in the rotation has been nearly as beneficial as the 
periodical applications of farm manure, even though the position of 
the beet crop in the alfalfa rotations has not been so favorable as in 
the manured rotations. It is also to be remarked that while both 
manure and alfalfa have increased the yield of the beets, the size of 
beets, and the vigor of growth, as expressed in the larger proportion 
of tops, there has not been a corresponding increase in the per- 
centage of sugar in the beets. 
Table V. — Comparison of the effect of farm manure and of alfalfa on subsequent yields 
of sugar beets in irrigated-crop rotations at the Scottsbluff, Belle Fourche, and Huntley 
Field Stations. 
Mean yields per acre. 
Factors compared. 
Scottsbluff. 
Belle Fourche. 
Huntley. 
Manure. 
Alfalfa. 
Manure. 
Alfalfa. 
Manure. 
Alfalfa. 
Yield of treated and untreated 
plats tons . . 
Annual difference do 
Size of beets pounds. . 
Annual difference in size, do 
Sugar in beets per cent . . 
Annual difference. do 
Yield of tops do 
15.3 
+4.3±-28 
1.55 
+.32±.044 
16.5 
-.12±.20 
26 
+2.7±.6 
13.8 
+3.4±.5 
1.53 
+.39±.032 
17.0 
+ .5±.15 
27 
+ 2.3±.6 
10.7 
+1.9±.36 
.84 
+.08±.035 
19.6 
+ .3±.22 
9.9 
+.64±.36 
.78 
+.08±.035 
19.7 
+ ,5±.19 
11.3 
+2.6±.33 
.92 
+.21±.034 
16.8 
+.16±.17 
32 
+3. 2±1. 12 
10.7 
+1.5±.6 
.96 
+.17±.05 
17.0 
-1.3±.22 
38 
Annual difference 
+ 8. Oil. 8 
SUMMARY. 
The effect of a period of two or three years of alfalfa in a rotation 
on the subsequent yields of Irish potatoes, oats, and sugar beets 
grown under irrigation has been tested for six years at three different 
stations in the northern Great Plains. Comparison is made between 
the yields of these crops when grown in the same sequence but with- 
out alfalfa. A further comparison is made in the case of potatoes 
and sugar beets as to the relative effect of a period of alfalfa in the 
rotation and the application of farm manure at the rate of 12 tons 
per acre once during the period of the rotation. 
At Scottsbluff, Nebr., where the soil is light sandy loam, the effect 
of alfalfa has been to increase the yield of potatoes about 100 bushels 
per acre, to increase the proportion of marketable potatoes about 12 
per cent, to increase the yield of oats about 6 bushels per acre, and 
to increase the yield of sugar beets 3.4 tons per acre. 
1 Scofield, C. S. Loc. cit. 
