World’s Soil Resources

Photo by T.M. Zobeck
Figure 6.4 Dust storm near Meadow, Texas, USA
At the field and landscape scales, wind erosion winnows the finer and more chemically active portion
of the soil which carries biogeochemicals, including plant nutrients, soil carbon and microbial products. In
some cases, wind erosion processes modify the surface properties by causing increases in sand content while
reducing the soil water holding capacity and plant productivity (Zobeck and Van Pelt, 2011). Although some of
this eroded sediment is deposited relatively close to field boundaries, often much of it enters into suspended
mode and may be transported high in the atmosphere to travel great distances. This long-range transport of
dust produces effects at the global and regional scales Atmospheric dust produced by wind erosion profoundly
influences the energy balance of the Earth system by carrying organic material, iron, phosphorus and other
nutrients to the oceans, affecting ocean productivity and subsequent ocean-atmosphere CO 2
exchange (Shao
et al., 2011).
6.1.7 | Effects of hydrology and water
Wind erodibility and subsequent erosion and dust emissions are affected by hydrology and water in several
ways. Remote sensing studies of dust sources by Prospero et al. (2002) showed that many major dust sources
originate from deep alluvial deposits formed by intermittent flooding during the Quaternary and Holocene.
These sources, now in drylands, originated when water was more plentiful and produced an ample supply of
wind-erodible sediment (Ginoux et al., 2012). In many areas, particularly in areas with more limited erodible
sediment supply, dust emissions increase after new inundations of ephemeral water supplies provide additional
erodible sediment. However, many fluvial-related dust sources have also developed from the exposure, due to
anthropogenic factors, of the bottoms of former lakes such as at Owens Lake in the United States (Reheis,
1997) and the Aral Sea Basin in Uzbekistan (Singer et al., 2003). In these cases, usually water has been extracted
from the lake for irrigation or human consumptive needs. This issue will be accentuated as increasing demand
for water in dryland regions is met from reservoirs.
Status of the World’s Soil Resources | Main Report Global soil status, processes and trends
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