16 BULLETIN 1139, 17. S. DEPARTMENT OE AGRICULTURE. 
of rain between harvest and seeding has been large enough to wet 
thoroughly all the soil on all plats practically every year. This limi- 
tation of storage capacity has had the effect of eliminating differences 
between different cultivation methods in the quantity of moisture 
conserved. Edgelev is the only station included with such a limited 
water-storage capacity that it has been practically all utilized each 
year by all methods of cultivation. 
The soil at Belle Fourche is a heavy clay which changes to open 
partially decomposed shale in the fourth foot. In this soil there is 
no layer that prohibits moisture penetration, but the soil at the 
depth of about 2 feet is compact and swells so much when wet that 
water movement through it is very slow. 6 
Penetration by roots is likewise difficult, and even when available 
moisture has been present in the lower depths the feeding depth of the 
wheat crop has been limited to a little less than 3 feet. Evidently 
the roots penetrate into the third foot only as necessity requires, and 
they have not been able to reach a depth greater than 3 feet before 
death or the ripening of the crop occurs. For practical purposes there 
is no need of considering the soil below the third foot. In spite of 
the limited water-storage capacity of the soil, there have been only 
two years when plats A and B have been filled to capacity. There 
has been practically no difference between the two plats in this 
respect. Plat C or D has been wet to capacity in all but two years. 
Belle Fourche represents a station where the demands of the crop for 
water have been so heavy that the soil moisture has been exhausted 
in all plats each year at harvest. The only exception is plat C or 
D in 1911. In that year climatic conditions were so adverse that the 
crop on the other plats did not germinate and on this plat suffered 
from drought and heat almost from the time it came up. It made 
such a limited growth that the roots were not able to extend to a 
depth of more than 2 feet. 
The soil at Ardmore is a heawy clay that changes into fine sand 
in the fifth and sixth foot sections. The moisture results show that 
changes in the water content occur below a depth of 1 feet, but the 
difficulty in sampling the fifth and sixth foot sections has been so 
great that sampling has been limited to 4 feet in all but one year. 
As far as the first 4 feet of soil is concerned, there has been prac- 
tically no difference in the moisture status of plats A and B. The 
extent to which plat C or D is superior to plats A and B in moisture 
stored can not be determined, as changes in moisture content evi- 
dently have occurred below the fourth foot. The quantity of water 
used from below the fourth foot, however, can not be large, as plat 
C or D is little superior to the other plats in point of yield. 
Archer represents a station with a soil depth of approximately 
4 feet. Below the fourth foot is a bed of gravel that prohibits 
sampling to a greater depth. It is doubtful whether moisture has 
penetrated deeper than 4 feet on plats A and B, and in only one year 
is it probable that water was stored at a depth lower than 4 feet on 
plat C or D. Plats A and B have approached each other very closely 
in water stored, utilization of water, and yield. Plat C or D has been 
little superior to plats A and B in storing moisture. This is re- 
6 Mathews. O. E. Water penetration in the gumbo soils of the Belle Fourche Reclama- 
tion Project. U. S. Dept. Agr. Bui. 447, 12 pp.. 4 fig. 1916. 
