284 DRY-FARMING 
to-day than they did a generation ago. Strangely 
cnough, this is not true of the irrigated farms, operat- 
ing under like soil and climatic conditions. This 
behavior of crop production under dry-farm condi- 
tions has led to the belief that the question of soil- 
fertility is not an important one to dry-farmers. 
Nevertheless, if our ‘present theories of plant nutri- 
tion are correct, it is also true that, if continuous 
cropping is practiced on ouy dry-farm soils without 
some form of manuring, the time must come when 
the productive power of the soils will be injured and 
the only recourse of the farmer will be to return to the 
soils some of the plant-food taken from it. 
The view that soil fertility is not diminished by 
dry-farming appears at first sight to be strengthened 
by the results obtained by investigators who have 
made determinations of the actual plant-food in 
soils that have long been dry-farmed. The sparsely 
settled condition of the dry-farm territory furnishes 
as yet an excellent opportunity to compare virgin 
and dry-farmed lands and which frequently may be 
found side by side in even the older dry-farm sections. 
Stewart found that Utah dry-farm soils, cultivated 
for fifteen to forty years and never manured, were 
in many cases richer in nitrogen than neighboring 
virgin lands. Bradley found that the soils of the 
great dry-farm wheat belt of Eastern Oregon con- 
tained, after having been farmed for a quarter of a 
century, practically as much nitrogen as the adjoin- 
