Soil Enzyme Stability as an Ecosystem Indicator

EPA Grant Number: R826592
Title: Soil Enzyme Stability as an Ecosystem Indicator
Investigators: Dick, Richard P.
Institution: Oregon State University
EPA Project Officer: Hahn, Intaek
Project Period: August 19, 1998 through August 18, 2000
Project Amount: $196,806
RFA: Ecological Indicators (1998) RFA Text |  Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , Ecosystems


Sustainability assessment of ecosystems is a national priority in order to assist land managers and policy makers to promote long-term sustainability, yet quantifying environmental sustainability remains an elusive goal. One approach is to use the soil as an indicator of ecosystem 'health'. Unlike air and water where standards of quality have been established, soil quality definition and application is complicated by analytical complexities, high variability, and multiplicity of physical, chemical, and biological factors which control biogeochemical processes. Previous work in our laboratory suggests use of soil enzymes has potential to overcome drawbacks of other soil quality approaches and is an integrative index of the cumulative effect of soil management on soil biology and that this is closely related to soil structural development (aggregation).

Specific objectives are as follows:

  • To refine microwave enzyme stress test for maximum sensitivity in detecting soil management/stressors as a soil quality and ecosystem indicator.
  • Determine temporal dynamics of selected soil enzyme activities and MWES (microwave enzyme stress) across diverse agro-ecosystems.
  • Investigate the relationship of soil enzyme activities to other soil properties to develop conceptual models on the role of enzyme activity and stability to be an indicator of soil quality.


Soil enzyme activity assays are advantageous as a potential indicator because: of operational practicality; they are sensitive integrative 'biological fingerprints' of past soil management; and there appears to be a relationship between soil enzyme activity and soil aggregation, linking enzymes with soil tilth. However, there have been no systematic studies across agro-ecosystems on the potential of soil enzyme activities to assess soil quality. Because soil properties, including soil enzyme activities, vary widely as a function of soil type, the primary goal of the proposed research is to develop relative indexes that will allow assessment of soil quality without temporal or treatment comparisons. In the first year of the project, initial screening of 3 promising soil enzyme assays as indicators will be done. Temporal variability of the activity and stability of these enzymes will be done at three experimental sites in Oregon (located in divergent forest and agro-ecosystems) where detailed management history is known and soils vary widely in soil 'health' (i.e. biological activity and organic matter content) because of past soil management. This will include refinement of sample handling and lab protocols to increase sensitivity and reproducibility of the indicators and temporal variability of these indicators. In the second year the refined protocols will be across a wider range of ecosystems and soil types. Two approaches for a relative index will be investigated: the first involves ratios of enzyme activity to other soil properties (e.g. total C, microbial biomass); and the second is a promising indicator, developed at Oregon State University called a thermal enzyme stress index. Besides soil eco-indicators, soil chemical, physical, and other biological properties will be investigated (particularly fungal relationships as fungal dominated soils appear to be a condition of undisturbed soils) to determine verify the role of indicators in predicting soil quality or health.

Expected Results:

This proposal outlines the steps to fully develop and test the feasibility of exploiting soil enzyme activities or soil enzyme stability as either stand-alone indicators or as part of a minimum data set to assess soil quality/health and reflect ecosystem status.

Publications and Presentations:

Publications have been submitted on this project: View all 8 publications for this project

Supplemental Keywords:

biotic enzymes, abiontic enzymes, humic-enzymes, fungal mycelium, substrate catalysis., RFA, Scientific Discipline, Ecosystem Protection/Environmental Exposure & Risk, Ecology, Ecosystem/Assessment/Indicators, Ecosystem Protection, Environmental Chemistry, Ecological Effects - Environmental Exposure & Risk, Agronomy, Geology, Ecological Indicators, ecological exposure, biogeochemical indicators, substrate catalysis, biomonitoring, ecosystem indicators, terrestrial, bioassay, environmental stress, soil enzyme, microwave enzyme stress test, agriculture ecosystems

Progress and Final Reports:

  • 1999 Progress Report
  • Final Report