Agriculture Reference
In-Depth Information
view is needed as a basis for the sustainable use of soils. The focus on temporal
features will allow improved understanding of various forms of soil degradation and
the full range of sustainable and unsustainable use of soil resources. We agree with
the conclusion made by Hall et al. (1982) that the highest priority should be given to
maintaining a favorable rooting volume. This automatically places those soils with
restrictive subsurface horizons in the category of high risk for maintaining a sustain-
able system of crop production.
The irreversible impact of reduced rooting depth on production may be slowed in
more fertile areas of the world with naturally deep A horizons. Areas such as those
containing Mollisols or Alfisols may show greater resistance to initial soil erosion where
the long-term severe impacts of topsoil removal may not yet have been fully experi-
enced. However, there are many regions of the world where disappearing A horizons
have greatly altered agriculture production and yield to unrecoverable levels (FAO 2011).
Soil and crop management practices that increase soil erosion are often driven
by economic considerations. The impacts of erosion must be considered through
both long-term physical impacts to the land and economic impacts associated with
lost production. These impacts include the costs incurred to reduce or offset the
yield penalty associated with soil loss (Crosson 1997) as well as fertilizer input use
increases to compensate for declines in soil quality due to erosion (ERS 1997; Den
Biggelaar et al. 2001). Nutrient losses, direct damage to plants, and offsite damages
must also be considered (Larson et al. 1983). Despite the impacts of soil erosion, the
world has managed to maintain and even increase production levels through tech-
nological advances. However, to take advantage of technological advances leading
to greater productivity, especially those related to plant genetics, soil quality must
be sufficient to supply increasing amounts of water and nutrients, as deficiencies in
either of these will negate increased plant production potential.
Globally, evidence strongly suggests that erosion of agricultural soils is occurring at
a rate considerably greater than soil renewal rates. Soil erosion-based land degradation
varies greatly in space and time. The temporal component of soil erosion is being aggra-
vated by increased frequencies of heavy rainfall events attributed to a changing global
climate and increased production pressure placed on land due to elevated demand for
agricultural products. As elevated demand draws additional land into production, spatial
soil erosion will almost certainly increase as well, especially erosion associated with
farming environmentally sensitive lands that offer agriculture production potential.
The imbalance between soil erosion and soil renewal presents a dilemma often
centered on human choices. Minimizing soil loss through appropriate management,
while maintaining existing production, is often a choice avoided for financial, politi-
cal, or cultural reasons. As previous civilizations have failed due to soil misuse and/
or abuse, as inferred by Franklin D. Roosevelt, our choice to sustain or degrade our
soil resources is a choice of self-preservation or self-destruction.
ABBREVIATIONS
IDEP:
Iowa Daily Erosion Project
NRCS:
Natural Resources Conservation Service of the United States
Department of Agriculture
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