138 DRY-FARMING 
farmer does not want his soils to be unnecessarily 
moist. The dry-farmer can reduce the per cent of 
water in the soil without diminishing the total amount 
of water by so treating the soil that the water will 
distribute itself to considerable depths. This brings 
into prominence again the practices of fall plowing, 
deep plowing, subsoiling, and the choice of deep soils 
for dry-farming. 
Very much for the same reasons, evaporation goes 
on more slowly from water in which salt or other 
substances have been dissolved. The attraction 
between the water and the dissolved salt seems to 
be strong enough to resist partially the force causing 
evaporation. Soil-water always contains some of 
the soil ingredients in solut on, and consequently 
under the given conditions evaporation occurs more 
slowly from soil-water than from pure water. Now, 
the more fertile a soil is, that is, the more soluble 
plant-food it contains, the more material will be 
dissolved in the soil-water, and as a result the more 
slowly will evaporation take place. Fallowing, 
cultivation, thorough plowing and manuring, which. 
increase the store of soluble plant-food, all tend to 
diminish evaporation. While these conditions may 
have little value in the eyes of the armer who is 
under an abundant rainfall, they are of great impor- 
tance to the dry-farmer. It is only by utilizing every 
possibility of conserving water and fertility that dry- 
farming may be made a perfectly safe practice. 
