CHAPTER Ix 
REGULATING THE TRANSPIRATION 
Water that has entered the soil may be lost in 
three ways. First, it may escape by downward 
seepage, whereby it passes beyond the reach of plant 
roots and often reaches the standing water. In dry- 
farm districts such loss is a rare occurrence, for the 
natural precipitation is not sufficiently large to con- 
nect with the country drainage, and it may, therefore, 
be eliminated from consideration. Second, soil- 
water may be lost by direct evaporation from the sur- 
face soil. The conditions prevailing in arid districts 
favor strongly this manner of loss of soil-moisture. 
It has been shown, however, in the preceding chapter 
that the farmer, by proper and persistent cultivation 
of the topsoil, has it in his power to reduce this 
loss enough to be almost negligible in the farmer’s 
consideration. Third, soil-water may be lost by 
evaporation from the plants themselves. While it 
is not generally understood, this source of loss is, in 
districts where dry-farming is properly carried on, 
very much larger than that resulting either from seep- 
age or from direct evaporation. While plants are 
growing, evaporation from plants, ordinarily called 
transpiration, continues. Experiments performed 
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