Marginality Principle - Principles of Sustainable Soil Management in Agroecosystems - page 40

64 tons of soil per acre lost in single events in some locations (Cox et al. 2011). Under
climate change predictions, not only are global temperatures rising but also localized
regional precipitation patterns are expected to continue to shift, creating drought in
some places (increasing potential of wind erosion to soil when exposed) and more
severe flooding in others, increasing the potential for greater soil losses. The soils of
the world, with the biota they support, are major sources of C and function as absorb-
ers, depositories, and releasers of organic C (Hillel and Rosenzweig 2011). Human
preferences for particular uses of soils will influence the extent to which these soil
functions mitigate climate by absorbing and storing C or become additional sources
of CO 2 , CH 4 , and N 2 O release.
2.7.1 S ocial D efinitionS of m arginality
The social meanings of soil quality and marginality can be broadly grouped into
three categories: (1) expert soil scientist classifications based on soil properties;
(2) interpretations of scientific classifications as codified and standardized in publi-
cally available materials such as soil surveys for use by professionals such as engi-
neers, government agencies and technicians, extension educators, tax assessors, and
real estate appraisers as well as landowners evaluating functional and market values
for personal uses; and (3) soils made marginal or enhanced by climate and anthro-
pological activities. Human values determine definitions and meanings, which guide
decisions and actions (Morton and Padgitt 2005). Expert soil scientist classifications
provide objective knowledge or facts, which can be used (or ignored) to make inter-
pretations and judgments about soil quality and marginality. However, human deci-
sions and applications are made outside of science. Science tells us the way the world
is and what might happen under certain conditions; it cannot tell us what decision to
make (Anderson-Wilk 2008).
The expected use and function of a particular parcel of land and its soil char-
acteristics determines its value from a human point of view. However, there are
considerable variations between scientists and nonscientists, between farmers and
nonfarmers, and among farmers as to values associated with soils and potential uses.
If the parcel does not have the “right” soils for the preferred use, it is likely to be
considered marginal from a nonsoil-scientist point of view. Thus, a wetland has mar-
ginal soils if you wish to grow grain or vegetable crops, but if the goal is nutrient
storage and cycling and wetland habitats, it is likely not to be considered marginal
from one who values those services. A rocky gorge or steep mountainside might be
considered marginal soils from a soil classification system but considered just right
and not marginal at all for a public park, a recreational hiking trail, or a homeowner
seeking a perfect vista.
Moisture holding capacity is one characteristic of soil quality highly valued by
some farmers, followed closely by soil texture and visible organic matter ( Table 2.4 ;
Lasley 1993). There are publics that claim that rural countrysides are becoming agri-
cultural industrial zones and ecological sacrifice areas and advocate the return of
cultivated cropland to an original state such as forests, grasslands, and prairies in
order to protect soil and ecosystem resources (Jackson and Jackson 2002). There are
economic developers that envision vibrant suburban and urban housing or industrial