Soil health indexing for dynamic
monitoring needs identifying new microbial indicators and focus on their
diversity in soil
The theme area of the earlier issue of the Newsletter 2(2) was
soil biological health to address the role of soil biology under continued
fertilizer use, key management steps for sustenance of productivity based on
up-to-date research, and finally identifying a few missing links in research
agenda to address soil biological properties. In this issue, having accepted
the role of soil biology to maintain soil health, I would like to take the
discussion forward towards gaps in our understanding of soil health or soil
quality, and the dynamic monitoring needs to identify new microbial indicators
with focus on their diversity.
Soil health is the result of continuous conservation and degradation
processes and represents the continued capacity of soil to function as a vital
living ecosystem. Although many
indicators and indices of soil quality or soil health have been proposed, a
globally acceptable and applicable definition and methodology of assessment of
soil quality or soil health are still at large. Further, the existing knowledge
provides a better understanding of the current capacity of a soil to function than
of making predictions about capacity of the soil to continue to function under
a range of stresses and disturbances. Another limitation of most of the
available studies is that efforts have been made to measure soil characteristics
in surface soil and not in the whole profile.
It
is known that unique balance of chemical, physical and biological (including
microbial) components should contribute to maintaining soil health. Evaluation
of soil health therefore requires indicators of all these components,
specifically the contributions of microorganisms and the pros and cons of using
them as early warning indicators of environmental changes. Microorganisms
appear to be excellent indicators of soil health because they respond quickly
to changes in the soil ecosystem and have intimate relations with their
surroundings due to their high surface to volume ratio. In some instances,
changes in microbial populations or activity can precede detectable changes in
soil physical and chemical properties, thereby providing an early sign of soil
improvement or an early warning of soil degradation.
According to Danish government strategy projected by NERI (Technical
Report no. 388) further scientific knowledge should be developed through
research activities included in the monitoring programme, and research on microbial biodiversity should be
in focus. Implementation of new indicators is recommended
as soon as these are applicable for soil monitoring purposes. These new
indicators should be based on continuous development of microbial methods within
the scientific community and will provide more precise, detailed and integrated
results in order to give a dynamic up-to-date monitoring programme.
Implementation is recommended in parallel with the existing measurements to
assure the quality and comparability of the new indicators as the old
indicators are phased out. The data sets of the new indicators can be used as
the baseline for future monitoring activities.
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