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 solution,
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 farmer who is under an
abundant rainfall, they are of great importance 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.
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