Research
Depressional soils in eastern Nebraska
Improving student proficiency at the texture-by-feel method
Charcoal-enriched Anthropogenic Soils
Lecture tutorials for Introductory Soils
Depressional soils in eastern Nebraska
Loess-filled depressions are common in eastern Nebraska, but little is known about the pedogenic processes associated with these features. The goals of this study are to evaluate the variation of soil horizons within the depressions and to assess the relative influence of eluviation versus loess deposition in profile development.
Improving student proficiency at the texture-by-feel method
The texture-by-feel method is an essential field skill for soil scientists, but one that is difficult for students to master. Students’ success at learning to determine soil texture depends largely on their persistence at learning through trial-and-error using a variety of manipulative tests. The manipulative tests used to determine soil texture forms a body of traditional knowledge that has been passed down through soil science community, but the relationship of commonly used tests with laboratory measurements of soil texture lacks scientific study. The goal of this project is to scientifically study the relationship of common manipulative tests to the mass fractions of soil separates, as well as the impact of various instructional tools and methods on student success at learning the texture-by-feel method.
Nebraska ISee Soil Explorer
The ISee Soil Explorer is an application to help students to understand soil landscape relationships by viewing their location on soil property and terrain maps while observing soils in the field. The application was developed at Purdue University and initially included coverage of the state of Indiana. We are working in collaboration with Purdue to expand coverage of the ISee Soil Explorer to Nebraska by developing the Dominant Parent Material maps for the application.
Charcoal-enriched Anthropogenic Soils
Traditional charcoal production by burning in earthen mounds produces small areas of charcoal-enriched soils. These are numerous in the forest surrounding 18th-19th century iron furnaces that were fueled by charcoal. Our research examined sites of charcoal production in New York and Maryland in order to assess the long term impacts of charcoal in soils. .
Publications (Undergraduate papers that won the Metcalfe Student Manuscript contest)
Lindsay, A. 2017. Organic Carbon Analysis of Charcoal-Enriched Soils at Catoctin Mountain Park, MD. Natural Sciences Education 46. doi:10.4195/nse2017.01.0101
Hesson, K. 2016. Charcoal Hearth Soils: Remnants of the Iron Industry in the Northeastern U. S.. Natural Sciences Education 45. doi:10.4195/nse2016.02.0771
Lecture Tutorials for Introductory Soil Science
Lecture tutorials are an active learning tool that pairs short lectures with worksheets that encourage active engagement. The worksheets direct students to analyze difficult concepts and confront common misconceptions about the lecture material. Some lecture tutorials that we have developed for introductory soil science can be found at our Soil Tutorials page.
Publications
Turk, J. K. 2016. The Development and Evaluation of Lecture Tutorials for Introductory Soil Science. Natural Sciences Education 45. doi:10.4195/nse2016.0002
V horizons in Desert Landscapes
Vesicular (V) horizons are surface or near-surface horizons with a predominance of vesicular pores. They are critical to regulation of surface hydrology in desert landscapes. Our research uses computed tomography to analyze the pore geometry of V horizons, in order to determine how climate, disturbance, and ecological change affect the size and shape of vesicles.
Publications
Turk, J.K., and R.C. Graham. 2014. Analysis of vesicular porosity in soils using high-resolution X-ray computed tomography. Soil Science Society of America Journal 78: 868-880.
Turk, J.K., and R.C. Graham. 2011. Distribution and properties of vesicular horizons in the western United States. Soil Science Society of America Journal 75: 1436-1448.
Soil Development in Debris Flows
Frequent debris flows in the San Bernardino Mountains, California form a chronosequence of young soils (<1 to 240 yrs). During this stage soil development most morphologic changes are driven by organic matter accumulation. Debris flows of different ages can be distinguished based on carbon and nitrogen stocks, the thickness and fungal mat development of the O horizons, and color and bulk density of the A horizons.
Publications
Turk, J.K., and R.C. Graham. 2009. Soil carbon and nitrogen accumulation in a
forested debris flow chronosequence, California. Soil Science Society of America Journal 73:1504-1509.
Turk, J.K., B.R. Goforth, R.C. Graham, and K.J. Kendrick. 2008. Soil morphology of a debris flow chronosequence in a coniferous forest, southern California, USA. Geoderma 146:157-165.
