EFFECT OF ALFALFA ON YIELDS OF FIELD CROPS. \) 
At Scottsbluff the yield of oats, grain, for the 62 plat years has 
averaged 58 bushels per acre, with a mean annual difference in favor 
of those following alfalfa of 6 ±1.3. The yield of straw from these 
same plats, omitting the crop of 1915, which was injured by hail 
and cut with a mower, has averaged 1.28 tons per acre, with a mean 
annual difference in favor of the plats following alfalfa of 0.30 ±0.05. 
Thus, while the yield of grain following alfalfa was increased by 10 
per cent of the mean yield of all plats, the yield of straw was increased 
by 23 per cent. 
At Belle Fourche the yield of grain for the 62 plat years has aver- 
aged 72 bushels per acre, with a mean annual difference in favor of 
those following alfalfa of 5 ±3. The yield of straw from these same 
plats has averaged 1.24 tons per acre, with a" mean annual difference 
in favor of the plats following alfalfa of 0.31 ±0.06. Thus, the yield 
of grain following alfalfa has been increased by 7 per cent, while the 
yield of straw has been increased 25 per cent. 
At Huntley the yield of grain for the 42 plat years has averaged 88 
bushels per acre, with a mean annual difference in favor of the plats 
following alfalfa of 11 ±3.7. The yield of straw from these same 
plats has averaged 1.51 tons per acre, with a mean annual difference 
in favor of the plats following alfalfa of 0.55 ±0.05. Thus, while the 
increase in the yield of grain has been 12.5 per cent, the increase in the 
yield of straw has been 36 per cent. 
SUGAR BEETS. 
The effect of alfalfa on the yield of sugar beets is shown in Table IV. 
Five pairs of rotations are reported for Scottsbluff and Belle Fourche 
and four pairs for Huntley. Two of the rotations at each station 
cover four years, the sugar-beet crop of 1914 being the first to come 
on plats that had been in alfalfa. The normal course of the rotation 
was not in effect in these cases until 1915. In the other rotations 
the first alfalfa effect reached the beet crop only in 1915, and the full 
effect of three years of alfalfa was not obtained until the crop of 1917. 
Coming, as it does, in the second or third year after the alf alf a, the 
sugar-beet crop can not be expected to show the benefits of alfalfa 
in the rotation that are shown by the potatoes and oats. Yet in 
the 14 comparisons of mean yields shown in Table IV, 5 of the 
means show significant differences in favor of the alfalfa rotations; 
1 shows a significant difference against alfalfa, and 8 show differences 
that are not significant. 
If we consider only the comparisons in which the full course of 
alfalfa has been in effect, i. e., the yields for 1917 and 1918 for the 
6-year rotations, we have 40 annual comparisons, of which 24 show 
increased yields of 1 ton or more for the beets following alfalfa, while 
8 show decreases of 1 ton or more, and 8 show differences of less 
than 1 ton per acre. 
