Organic Matter and Sustainability - Sustainable Management of Soil Organic Matter - page 2

defining 'sustainability', there is a consensus that soil organic matter has a
significant role to play in the sustainability of farming systems (Swift and
Woomer, 1993) and that it is an important indicator of soil quality and
productivity (Larson and Pierce, 1994). Costanza et al . (1997) identified
17 key ecosystem services on a global scale, eight of which include soil as a
critical component and most of which involve organic matter.
The objectives of this chapter are briefly to introduce some approaches
used to characterize sustainability in agroecosystems and their implications
for soil organic matter management; to address the concept of 'soil quality'
as a framework to evaluate soil functions and its possible role in soil organic
matter quality evaluation; and to examine the interrelationships between
organic matter and other soil properties that regulate and control the
functional purpose of organic matter in soil.

Soil Organic Matter and Sustainable Land Management

Soils are part of a larger environmental system called 'land', which reflects
the natural integration of soil, water, climate, landscape and vegetation
characteristics (FAO, 1976; Carter et al ., 1997). There are many and varied
approaches used to define and assess sustainability (Farshad and Zinck,
1993). Smyth and Dumanski (1995) proposed five components that
integrate environmental and socioeconomic principles that must be
satisfied to attain sustainable land management (Box 1.2). Generally, these
components are based on indicators of performance over time, with each
indicator given a 'threshold' or critical value, which is associated with a
significant decline or adverse change in land use sustainability. Gomez et al .
(1996) illustrated the use of the above approach, based on threshold levels
using soil organic matter as an indicator of natural resource protection, to
evaluate the sustainability of several farms in the Philippines.
The sustainability components given in Box 1.2 can be reduced
to three major areas: natural resource protection (including protection of
adjacent ecosystems), economic viability (including productivity and
security) and social acceptability (including natural use and aesthetic

Box 1.2. Components of sustainable land management (after Smyth and Dumanski, 1995).

Productivity- maintain and enhance production
Security- reduce level of production risks
Protection - protect the quality of natural resources and prevent soil degradation and
conserve soil resource
Viability- maintain economic viability
Acceptability- be socially acceptable