280 REPORTS ON THE STATE OF 
the soil in 1911, but unavailable to the 1911 crop because the inter 
vening soil was reduced to the wilting coefficient before the root 
system was established. It would be difficult to interpret these 
moisture conditions without the aid of the wilting coefficient determina- 
tions, especially where the moisture-retentivity of the soil and sub- 
soil is not the same, as in the case of the Dickinson soils. 
The growth-water content at seedtime and harvest in two plats at 
Akron, Colorado, is shown graphically in fig. 7 for six years. These 
plats form part of the cultural experiments of the Office of Dry-Land 
Agriculture, and are continuously cropped to spring wheat, A being 
spring -ploughed and B fall-ploughed. The width of the shaded 
portion in each foot-section shows the amount of growth-water. . It 
will be noted that the growth-water was in every instance practically 
exhausted at harvest-time, with the exception of the surface-foot, which 
in some instances had been moistened by rains near the harvest 
period. It also appears that at this station the time of ploughing has 
little influence on the soil moisture-content. 
Maintenance of the Fertility of the Dry-Farm. 
The maintenance of fertility under a system of continuous grain- 
farming, such as is practised in many dry-farming sections, bids fair 
to become a more and more serious problem as the years advance. 
‘The period of cultivation of much of the dry-farm land has been so 
short as to afford no information on this point. In any event, it 1s 
hardly a problem that can be taken up with the man who breaks the 
virgin land. His first concern is for bread, and his chief desire is to 
draw upon the resources of his land to its fullest capacity. It is only 
after a marked decrease in production has occurred that he will listen 
to measures designed to maintain the fertility of the soil. Happily, 
grain-farming as ‘practised on some of the oldest dry-farms in Utah 
does not yet appear to have diminished the productiveness of the soil. 
This is doubtless due in part at least to the fact that the wheat has 
been cut with a header (or more recently with a combined harvester), 
which leaves most of the straw on the land. Stewart and Hirst *° 
have found that the humus and nitrogen content of the surface soil of 
the wheat lands farmed for ten years or more has not fallen below 
that of adjacent virgin soils. In an earlier investigation, Stewart °° 
found that the oldest wheat lands in Utah, under cultivation for fourteen 
to forty-one years, either continuously or by summer-fallowing methods, 
had showed no loss in humus or nitrogen in the surface-foot. The second 
foot of the cultivated soils showed, however, a slightly lower nitrogen- 
content than the virgin land. The yield also appears to have been 
maintained. 
A wanton waste of organic matter occurs in many dry-farming 
sections in the northern Great Plains and in California. The stubble 
is burned to make the ploughing easier and to destroy weed-seeds, and 
the straw-stacks are burned in the field because they are in the path 
of the ploughs. As the ploughing-season approaches, the horizon is 
29 Jour. Am. Soc. Agron. 6, 49, 1914. 
°0 Utah Experiment Station, Bulletin 109, 1910. 
