ÜDS-Fen 2001-2 Soru=74

It is pointed out in the passage that the loss of organic matter in the soil .

Erosion is regarded not merely as the physical removal
of soil by water and wind, but rather as the deterioration
of all the component parts of the habitat in which man
and his crops and livestock have to exist. Since there is
no conclusive evidence for any major climatic change in
historic times to explain this deterioration, we must
conclude that the eroding of the total environment has
been due primarily to thoughtless destruction of the
vegetative cover. This has led to deterioration of the
microclimate above and below the surface, generally in
the direction of a general drying out of the soil which has
exposed it to erosive action of wind and rainfall of high
intensity or frequency, and to the loss of organic matter in
the soil, thus reducing its capacity to resist erosion by
conserving the water that falls on the surface. If
everything possible is done within the total environment
to conserve the naturally planted or cultivated vegetation,
this will also ensure optimal conservation of soil and
water.