Indicators of Sustainability - Agroecology: The Ecology of Sustainable Food Systems - page 302

kind of social, cultural, or economic pressure. For example,
it is a common occurrence for traditional farmers to shorten
fallow periods or increase their herds of grazing animals in
response to higher rents or other economic pressures and to
have these changes cause soil erosion or reduction in soil
fertility. We will devote more attention to the link between
social systems and sustainability in Chapter 23 and
Chapter 24.
It is essential that traditional agroecosystems be rec-
ognized as examples of sophisticated, applied ecological
knowledge. Otherwise, the so-called modernization pro-
cess in agriculture will continue to destroy the time-tested
knowledge they embody — knowledge that should serve
as a starting point for the conversion to the more sustain-
able agroecosystems of the future.

salaries and benefits may mask these signs, and an
integrated analysis in necessary to detect them. A sustain-
able agroecosystem will show health and happiness in all
segments of the social fabric of the food system.
In practice, distinguishing between systems that are
degrading their foundations and those that are not is not as
straightforward as it may seem. A multitude of ecological
and social parameters, all interacting, determine sustain-
ability — considering each one independently or relying
on only a few may prove misleading. Moreover, some
parameters are more critical than others, and the gains in
one area may compensate for losses in another. A chal-
lenge for agroecological research is to learn how the
parameters interact and to determine their relative impor-
tance (Gliessman, 1990, 1995, 2001; Giampietro, 2004).
In addition, analysis of agroecosystem sustainability
or unsustainability can be applied in a variety of ways.
Researchers or farmers may want to do any of the following,
alone or in combination:

DEFINING AND MEASURING
AGRICULTURAL SUSTAINABILITY

If we are concerned about maintaining the productivity of
our food production systems over the long term, we need
to be able to distinguish between systems that remain
temporarily productive because of their high levels of
inputs or external subsidies, and those that can remain
productive indefinitely. This involves being able to predict
where a system is headed — how its productivity will
change in the future. We can do this through analysis of
agroecosystem processes and conditions in the present.
A central question involves how a system's ecological
parameters are changing over time. Are the ecological
foundations of system productivity being maintained or
enhanced, or are they being degraded in some way? An
agroecosystem that will someday become unproductive
gives us numerous hints of its future condition. Despite
continuing to give acceptable yields, its underlying foun-
dation is being destroyed. Its topsoil may be gradually
eroding year by year; salts may be accumulating; the
diversity of its soil biota may be declining. Inputs of
fertilizers and pesticides may mask these signs of degra-
dation, but they are there nonetheless for the farmer or
agroecological researcher to detect. In contrast, a sustain-
able agroecosystem will show no signs of underlying deg-
radation. Its topsoil depth will hold steady or increase; the
diversity of its soil biota will remain consistently high.
Equally important is the question of the maintenance
of farmer, farm family, and farm community livelihoods.
Are the elements of social health and welfare being main-
tained so that farm families are able to enjoy a dignified,
healthy life with opportunities for education, personal
growth, and food security? Even if economic returns hold
steady in a region, individual farmers may have to leave
farming, children may be taken out of school to work on
the farm, or local opportunities for employment may be
reduced. Reducing the number of crops to meet market
requirements or hiring undocumented labor at lower

• Provide evidence of unsustainability on an indi-

vidual farm in order to motivate changes in the
practices on that farm.

• Provide evidence of the unsustainability of con-

ventional practices or systems more generally
to argue for changes in agricultural policy or
societal values regarding agriculture.

• Predict how long a system can remain productive.

• Prescribe specific ways of averting productive

collapse short of complete redesign of the agro-
ecosystem.

• Prescribe ways of converting to a sustainable

path through complete agroecosystem redesign.

• Develop supportive and equitable social rela-

tionships throughout the system.

• Suggest ways of restoring or regenerating a

degraded agroecosystem.

Although these applications of sustainability analysis
overlap, each represents a different focus and requires a
different kind of research approach.

A SSESSMENT OF S OIL H EALTH

In Chapter 8 and Chapter 9, we discussed the many ways
that farmers can manage soil factors. Depending on a
farmer's skill and experience, this management can lead
to improvement, degradation, or maintenance of the soil
conditions needed to maintain both production and the
qualities that promote it.
The overall picture of the condition of the soil — the
soil's fitness to support crop growth without degradation —
is called soil health . This term is used interchangeably
with soil quality. The methods that soil scientists
have developed to determine soil quality are usually fairly