EFFECT OF FALL IRRIGATION ON" CROP YIELDS. 
The experiments were conducted in duplicate each year, the seven 
plats in Series I duplicating those in Series III, while the plats in 
Series II and IV were duplicates. The following crop varieties were 
nsed: Oats, Great Dane in 1914 and Swedish Select in 1915 and 1916; 
sugar beets, South Dakota No. 40 in 1914 and Kleinwanzleben in 
1915 and 1916; flax, Minnesota No. 25; potatoes, Eureka in 1914 
and 1915 and U. S. No. 4452 in 1916; barley, Minnesota No. 6 in 
1914, Himalaya (Guy Mayle) in 1915, and Chevalier in 1916; corn, 
Payne White Dent in 1914 and 1916 and Martens White Dent in 
1915; and wheat, Defiance in 1914, Pringle Champlain in 1915, and 
Marquis in 1916. The positions occupied by the crops on each of 
the four series each year, the crop sequence' on each plat during the 
3-year period, and the number of summer irrigations applied are 
shown in Table II. 
Table II. — Sequence of crops and number of irrigations applied to each in the fall-irrigation 
experiments at the Belle Fourche Experiment Farm in 1914, 1915, and 1916. 
1914 
. 1915 
1916 
Plat. 
Crop. 
Num- 
ber of 
irriga- 
tions. 
Crop. 
Num- 
ber of 
irriga- 
tions. 
Crop. 
Num- 
ber of 
irriga- 
tions. 
No. 7 
Oats 
3 
3 
2 
4 
2 
3 
2 
Beets 
1 
2 
1 
1 
1 
2 
2 
Oats 1 
No. 8 . . 
Beets 
Flax 
No. 9 -. .. 
Flax 
Beets 2 
No. 10 . 
Wheat ... 1 
No. 11 
Corn .■ 
Barley 1 
No. 12 
Wheat 
Corn . 
No. 13 
Wheat 
Oats 
Flax 
1 
As shown in Table II, an intertilled crop followed a close-planted 
crop on each plat except No. 13 in 1915 and 1916 and No. 10 in 1916.' 
More irrigation was necessary in 1914 than in either 1915 or 1916, as 
the growing season of 1914 received somewhat less rainfall than either 
of the others. The variations in both crop sequence and summer 
irrigation were the same on all four series. 
All cultural operations on the four series were uniform as to both 
character and time of performance throughout the period of experi- 
ment. These included the ordinary operations incident to the pro- 
duction of the seven field crops involved. The land was manured 
from October 6 to 10, 1915, when 12 tons per acre of well-rotted 
barnyard manure were applied uniformly to all the plats. 
RESULTS OF THE EXPERIMENTS. 
In the conduct of these experiments attention was directed chiefly 
to the crop yields secured on fall-irrigated land as compared with 
those of land not so irrigated and to the soil-moisture conditions on 
the two groups of plats, particularly before the first summer irri- 
gation each season. It was to be expected that any important 
