ENR Graduate Exit Seminar

Emma M. Snyder will present Baseline Assessment of Dynamic Properties and Soil Resilience at Lawrence Woods State Nature Preserve in 460 Kottman Hall for her Graduate Exit Seminar.

As the world’s population continues to grow and food security issues intensify, so do concerns about soil resilience and soil quality. The term soil resilience refers to a soil’s ability to recover following a disturbance.  This relates to soil quality in terms of recovery of those soil functions that sustain biological activity, maintain environmental quality, and promote plant and animal health. A major challenge faced by those in this field of study is constructing a quantitative framework to measure and monitor soil resilience.

The first step in creating such a framework is to identify the physical, chemical, and biological properties of the soil ecosystem that are both sensitive and effective at indicating a disturbance.  The literature suggests that dynamic soil properties will serve as the best indicators of soil resilience as they readily change under anthropogenic intervention and can be detected over the course of the human time scale.  Of these indicators, there has been a focus on the biological properties because they are often the first to respond to change, even before changes in chemical properties have been detected.

The Lawrence Woods State Nature Preserve, approximately 1058 acres, consists of two major soil series, namely Blount (Bo) and Pewamo (Pm), and three major areas of differing land use, including the forest (Fr) and two agricultural plots.  The agricultural plot (Ag1) adjacent to the northern boundary of the woods underwent continuous long-term intensive cultivation until 2001 and the agricultural plot (Ag2) adjacent to the western boundary of the woods was cultivated, less intensely, until 1998. The unique juxtaposition of differing land management practices and degrees of degradation present at Lawrence Woods State Nature Preserve made it possible to observe the effects of disturbance on the different physical, chemical, and biological properties.  

A factorial design was used including the three land uses, two types, and three replications within each. A suite of physical, chemical, and biological properties was analyzed to establish baseline measurements and to also determine which of those properties served as the best dynamic indicators of resilience.  An analysis of variance was performed to determine if the difference between the properties and land uses was significant.  Through the data analysis, five properties were selected to be included in a resilience index as they were most indicative of disturbance for the Lawrence Woods site.

 The underlying theme in the literature concerning soil resilience is the need for a method of quantification.  With that being said, even the articles proposing a framework, do not provide a quantitative method for how resilience can be quantified.  The five properties that were selected as the best indicators of resilience include hydraulic conductivity, soil microbial biomass, % clay, bulk density, and average % total carbon.  The data from these five indicators was used to create a scoring system from (0-1) and a weighting factor for each of the indicators.  This facilitated the construction of a framework and an example of how to rate the resilience of a particular soil based on its soil mean value.  It was hypothesized that the most degraded soils (Ag1) would have the lowest resilience ratings compared with the less degraded soils including (Ag2) and the forest (Fr).

It should be stressed that this system is specific to the Lawrence Woods site. The primary objective is to generate a discussion amongst soil scientists of various disciplines to work together to derive the most comprehensive and effective method for quantifying soil resilience.