Agriculture Reference
In-Depth Information
example, remediation of pollutants or the biological control of pathogens.
How can we then start to think of engineering the transformation of organic
matter - to release nutrients in protected organic matter in low fertility
soils or to enhance protection of organic matter in soil subject to physical
degradation? These are some of the challenges that might be addressed by
gaining a greater understanding of how microbial diversity interacts with
organic matter.
Concluding Remarks
Land management must play a critical role in developing sustainable
strategies of land use in the coming decades. Although cultivation too
often in the past has been associated with organic matter loss and soil
degradation, we are now in a position to apply our understanding of crop
sequences and cultivations, many of which have been described in this
volume, in a way that can actively restore organic matter storage, thereby
restoring the functions that the soil supports. One of the characteristic
features of organic matter, unlike many other important soil properties, is
that it is significantly affected by management. Falloon
et al
. have shown
that land management can have a significant impact on the sequestration of
carbon by soils, thereby partially offsetting the imbalance between carbon
release and uptake by terrestrial systems. We now have a better understand-
ing of the relationships between organic matter quality and its function in
soil (Cadisch and Giller). However, there is still much progress to be made
in understanding how land management contributes to patterns of spatial
and temporal heterogeneity in soils, particularly given the problems that
this causes in relation to attempts to try to scale-up processes from the
micro scale to the level of an ecosystem.
Modelling of soil organic matter dynamics is likely to continue to
help in the understanding and management of the carbon cycle. This
is important both at the global scale, enabling projections of carbon
mitigation potentials in agriculture, and at the regional scale, enabling an
'optimum' organic matter level to be specified. Exceeding the optimum
is likely to cause significant losses of nitrogen in addition to carbon,
particularly during land use changes. Future developments are likely to
include a wider range of scales of modelling. At small scales, we need
further reconciliation of experimental and theoretical descriptions of soil
organic matter. At larger scales, where technical development of models is
well advanced, more acquisition of historical data on organic matter and
land use practices is required.
The scope of the papers presented here highlights the breadth
of approaches to soil organic matter research within the soil science
community, and the inter-disciplinary nature of soil science
per se
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