PARENT SESSION
Symposium #5: Sustaining and restoring our soil.
Sponsored by ESA Soil Ecology Section
Organized by: S.M. Adl. and S. Morris.
Monday, August 6, 2001. 1:00 PM to 4:50 PM. Madison Ballroom A

Microbiological indicators for monitoring changes in soil sustainability and quality.

Stenberg, Bo¹, ¹

ABSTRACT- The complex nature of soil quality allows it to be assessed only if the physical, chemical and biological components are represented. Generally, suggested minimal data sets are weighted towards physical and chemical indicators. However, the experience of microbiological indicators is increasing and methods are refined. Soil quality monitoring has the purpose of identifying risk areas for certain activities or land uses, to promote better soil management and sustainable land use. Monitoring soil sustainability or quality involves four equally important steps: i) sampling, including selection of sites, frequency in space and time and procedure, ii) analysis, including selection of indicators and methodology, iii) data interpretation, and iv) communication of results. This presentation will focus on analyses and data interpretation. The requirements are high on a data-set that should be able to describe all functions and aspects of soil quality; biomass production, filtering, buffering and transforming actions, biological habitat and gene reserve, spatial base for community structures, source of raw materials, etc. In addition, included indicators should be integrative, representative, relevant, sensitive, and cost-effective. The inclusion of microbiological indicators in a soil quality assessment strategy is crucial since they have fundamental functions in key processes such as the recirculation of organic matter and nutrients. In addition, they have the potential of being sensitive and integrative. This presentation suggests that chosen microbiological indicators should be possible to relate to soil functions and processes to ensure ecological relevance. The methodology applied should also be of such a nature that influences of short-term fluctuations in the soil environment are excluded. The evaluation of data addresses a series of fundamental problems in soil science; for example the complexity of the soil system, the variability in time and space at all scales, and the influence of external forces. Our experience of principal component analysis and partial least-square regression shows that they can give interpretable quality groupings of soils. Multivariate techniques have the potential to reveal the structure of the variation of all soil quality indicators needed to assess soil quality.

KEY WORDS: soil quality, soil health, microbial indicators, minimal data set