A healthy crop of sagebrush is an
almost absolutely certain indication that farming without irrigation
is feasible. The rabbit brush of the drier regions is also usually a
good indication, though it frequently indicates a soil not easily
handled. Greasewood, shadscale, and other related plants ordinarily
indicate heavy clay soils frequently charged with alkali. Such soils
should be the last choice for dry-farming purposes, though they
usually give good satisfaction under systems of irrigation. If the
native cedar or other native trees grow in profusion, it is another
indication of good dry-farm possibilities.
CHAPTER VI
THE ROOT SYSTEMS OF PLANTS
The great depth and high fertility of the soils of arid and semiarid
regions have made possible the profitable production of agricultural
plants under a rainfall very much lower than that of humid regions.
To make the principles of this system fully understood, it is
necessary to review briefly our knowledge of the root systems of
plants growing under arid conditions.
Functions of roots
The roots serve at least three distinct uses or purposes: First,
they give the plant a foothold in the earth; secondly, they enable
the plant to secure from the soil the large amount of water needed
in plant growth, and, thirdly, they enable the plant to secure the
indispensable mineral foods which can be obtained only from the
soil.
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