General Introduction - Integrated Assessment of Health and Sustainability of Agroecosystems - page 2

led to the articulation of a new outlook in agricultural development, embodied in
concepts such as sustainability and agroecosystem health.
Sustainable agriculture has been defined as the successful management of
resources for agriculture to satisfy changing human needs while maintaining or
enhancing the quality of the environment and conserving natural resources (Techni-
cal Advisory Committee, 1987). An agricultural system that is sustainable must be
resource conserving, socially supportive, commercially competitive, and environ-
mentally sound (Ikerd, 1990). It allows the demands for food and other products to
be met at a socially acceptable economic and environmental cost (Crosson, 1993).
In a sustainable system, agricultural activities would have little or no adverse effects
on their ecosystem and yet remain gainful (in terms of profits and other utilities) to
the producers themselves and to the wider social organization to which they belong
(Lynam, 1993).
In spite of an expanding ecological and economic literature on sustainability, the
concept has remained largely inoperative in applied research (Izac and Swift, 1994).
The main obstacle has been that the current definitions of sustainable agriculture,
although attractively holistic, are too vague and ambiguous to lead to clear-cut mea-
surements of the sustainability of specific agroecosystems (Izac and Swift, 1994).
It has been suggested that uncertainties inherent in holistic assessments can be
reduced by relying on trends in a group of carefully chosen attributes (Rapport and
Regier, 1980; Rapport, 1992). Measures of such attributes or their proxies—known
as indicators —assessed over time and space can provide an objective assessment of
sustainability. The agroecosystem health approach provides a framework through
which indicators of sustainability can be selected and measured.
Given this background, the general objective of this study was to carry out an
integrated assessment of agroecosystem health and sustainability with special focus
on smallholder farms in Kiambu District, Kenya. Specifically, the study aimed at
1. Adapting the agroecosystem health framework for use in a smallholder-
dominated tropical highlands agroecosystem.
2. Developing a suite of health and sustainability indicators for smallholder
farms in the Kiambu agroecosystem.
3. Using the selected indicators to assess health and sustainability of the systems.
4. Enabling farmers and communities to assess the health and sustainability
of their own agroecosystems.
5. Assessing the potential of various strategies in improving the health and
sustainability of the agroecosystem.
1.2 Global context
The world's population more than doubled over the decades 1950 to 1990, increasing
from 2.5 billion in 1950 to 5.3 billion in 1990 (Lynam, 1993). Because of this, most of
the earth's resources have had to be commanded for agricultural production. Agricul-
ture has become the most expansive land-use system in the world. Consequently, it is a
major determinant of the quality and quantity of other natural resources, such as fresh
water, forests, grasslands, and undomesticated plant and animal life (Lynam, 1993).