Agriculture Reference
In-Depth Information
LEVELS OF CONVERSION
primary emphasis of much conventional agricultural
research, through which numerous agricultural technolo-
gies and practices have been developed. Examples include
optimal crop spacing and density, improved machinery,
pest monitoring for improved pesticide application,
improved timing of operations, and precision farming for
optimal fertilizer and water placement. Although these
kinds of efforts reduce the negative impacts of conventional
agriculture, they do not help break its dependence on exter-
nal human inputs.
For many farmers, rapid conversion to sustainable agro-
ecosystem design and practice is neither possible nor prac-
tical. As a result, many conversion efforts proceed in
slower steps toward the ultimate goal of sustainability, or
are simply focused on developing food production systems
that are somewhat more environmentally sound. From the
observed range of conversion efforts, three distinct levels
of conversion have been discerned (MacRae et al., 1990;
Gliessman, 2004), and a fourth is proposed here. These
levels help us describe the steps that farmers actually take
in converting from conventional agroecosystems, and they
can serve as a map outlining a stepwise, evolutionary
conversion process. They are also helpful for categorizing
agricultural research as it relates to conversion, and for
considering what additional steps might be needed to
ensure that the conversion process promotes sustainability
in food systems beyond the farm.
L EVEL 2
Substitute conventional inputs and practices with alterna-
tive practices . The goal at this level of conversion is to
replace resource-intensive and environment-degrading
products and practices with those that are more environ-
mentally benign. Organic farming and biological agricul-
ture research has emphasized such an approach (Figure
20.2). Examples of alternative practices include the use of
nitrogen-fixing cover crops and rotations to replace syn-
thetic nitrogen fertilizers, the use of biological control
agents rather than pesticides, and the shift to reduced or
minimal tillage. At this level, the basic agroecosystem
structure is not greatly altered; hence many of the same
problems that occur in conventional systems also occur in
those with input substitution.
L EVEL 1
Increase the efficiency of conventional practices in order
to reduce the use and consumption of costly, scarce, or
environmentally damaging inputs . The goal of this
approach is to use inputs more efficiently so that fewer
inputs will be needed and the negative impacts of their
use will be reduced as well. This approach has been the
FIGURE 20.2 An on-farm study of a level-2 conversion process with strawberries on the central coast of California.
Conventional and organic practices are simultaneously compared for at least 3 years.
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