EFFECT OF FALL IRRIGATION ON CROP YIELDS. 
moisture than that of the check plats. On June 27 there were no 
significant differences in moisture content, all differences being less 
than their probable errors. It will be noted that the moisture con- 
tent of the fourth foot was practically the same on each of the three 
sampling dates. The results of the moisture determinations made 
in 1914 showed that while the soil of the fall-irrigated plats contained 
more moisture than that of the check plats early in the season, when 
all the plats had abundant moisture, the differences decreased as the 
season advanced and disappeared before the end of June. 
Table VI. — Summary of the results of soil-moisture determinations made in 1914 in- the 
fall-irrigation experiments at the Belle Fourche Experiment Farm. 
Depth. 
Fall-irrigated plats. 
Check plats. 
Date. 
Num- 
ber of 
plats 
aver- 
aged. 
Moisture 
content. 
Num- 1 
5£° f | Moisture - 
£,** content, 
aged. 
Difference 
in favor 
of fall 
irrigation. 
May 5 
Feet. 
1 
2 
3 
4 
1 
2 
3 
4 
1 
6 
6 
6 
6 
8 
8 
8 
8 
8 
Per cent. 
28.7+0.4 
28. 8± .4 
26. 6± .3 
21.7±1.0 
23. 1± .6 
25. 3± .7 
26. 5± .6 
21. 5± .8 
22. 3± .6 
25. 8± .4 
26. 4± .6 
20. 8± -8 
6 
6 
6 
6 
8 
8 
8 
8 
8 
8 
8 
8 
Per cent. 
25.1±0.6 
20. 5± .3 
21. 0± .3 
19. 5± .7 
21. 5± .7 
20. 3± .9 
20. 9± .5 
20. 2± .9 
22. 1± .7 
25. 0± -7 
26. 3± .9 
20. 7± .9 
Per cent. 
+3.6±0.7 
Do.... 
+8.3± .5 
Do .. 
+5.6± .4 
Do 
+2.2±1.2 
+ 1.6± .9 
Do 
+5.04-1.1 
Do . 
+5.6± .8 
Do 
+1.3±1.2 
June 27 . 
+ .2± .9 
Do 
2 1 8 
3 j 8 
4 8 
+ .8± .8 
Do 
+ .1±1.1 
Do 
+ .1±1.2 
Soil moisture in 1915. — The sampling in 1915 was done on May 24 
and June 10. All the plats in Series I and II were sampled on the 
first date and those in Series III and IV on the second. No irriga- 
tion water was applied to any of the plats in 1915 until July 14, so 
that the moisture determinations were made five and seven weeks, 
respectively, before the first irrigation. The samples were taken to 
a depth of 3 feet. Table VII gives a summary of the results of the 
moisture determinations, together with the probable errors of the 
averages of moisture content. 
Table VII. — Summary of the results of soil-moisture determinations made in 1915 in the 
fall-irrigation experiments at the Belle Fourche Experiment Farm. 
Date. 
May 24. 
Do. 
Do. 
June 10 
Do. 
Do. 
Depth. 
Feet. 
Fall-irrigated plats . 
Num- 
ber of 
plats 
aver- 
aged. 
Moisture 
content. 
Per cent. 
29.2±0.3 
29. 4± .4 
28. 1± .2 
30. 0± .3 
29. 8± .2 
27. 9± .3 
Check plats. 
Num- 
ber of 
plats 
aver- 
Moisture 
content. 
Per cent. 
30.4±0.2 
29. 4± .4 
26. 0± .9 
30. 3± .6 
29. 4± .6 
27. 6± .7 
Difference 
in favor 
of fall 
irrigation. 
Per cent. 
-1.2±0.3 

+2.1± .9 
- .3±-.7 
+ .4± .6 
+ .3± .8 
