There are some arid
soils, notably gypsum soils, the particles of which are so uniform
size that the pore-space is exceedingly small. Such soils are always
difficult to prepare for agricultural purposes.
It is the pore-space in soils that permits the storage of
soil-moisture; and it is always important for the farmer so to
maintain his soil that the pore-space is large enough to give him
the best results, not only for the storage of moisture, but for the
growth and development of roots, and for the entrance into the soil
of air, germ life, and other forces that aid in making the soil fit
for the habitation of plants. This can always be best accomplished,
as will be shown hereafter, by deep plowing, when the soil is not
too wet, the exposure of the plowed soil to the elements, the
frequent cultivation of the soil through the growing season, and the
admixture of organic matter. The natural soil structure at depths
not reached by the plow evidently cannot be vitally changed by the
farmer.
Hygroscopic soil-water
Under normal conditions, a certain amount of water is always found
in all things occurring naturally, soils included.
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