Author: Bradley Miller

What is Colluvium? An Interactive Poster Seeking a Common Definition to Improve International Communication (2015 SSSA Conference)

UPDATE: This poster was a test run for a survey asking the audience for their perspectives on how to differentiate colluvium and alluvium. That has now evolved into an online survey that you can now take. Respondents have told us that taking the survey was fun and thought-provoking. Please add your perspective by completing the … Continue reading What is Colluvium? An Interactive Poster Seeking a Common Definition to Improve International Communication (2015 SSSA Conference)

The use of soil surveys to aid in geologic mapping with an emphasis on the Eastern and Midwestern United States

After soil science became established as a scientific discipline, there has been a continued interplay between geologists and soil scientists, both fields benefiting from advancements made by the other. There is strong agreement between preliminary geology maps created from soil maps and traditional geology maps. Despite the results obtained when using soil maps to create surficial geology maps, there is a need for more quantitative studies to assess the degree of compliment between soil-based maps and traditional geology maps, expansion of the technique into a wider range of geologic and climatic environments, and more research in locations that use classification systems other than Soil Taxonomy.

The Real Benefits of Digital Soil Mapping

Proponents of digital soil mapping sometimes criticize traditional soil mapping for using a discrete data model to describe a continuous surface (field) and lacking a quantified estimation of error. Although most of my research is on digital soil mapping, I like to give due credit to the accomplishments of traditional soil mapping. I understand the need for … Continue reading The Real Benefits of Digital Soil Mapping

Surficial Geology of Iowa

This raster is a highly detailed (delineations made at the 1:15,840 scale) map of geologic materials at the surface, covering the entire state of Iowa. The map is based on the interpretations of the US Soil Survey, which regularly needs to assess the soil parent material in their mapping activities. The raster was generated from … Continue reading Surficial Geology of Iowa

Types of Measurement Error

We always want to avoid error, but it is a fact of life. At the foundation of analysis and modelling, we rely on measurements. Because errors in measurements are inescapable, the important question is how much does the error affect the result? I start the conversation by explaining what measurement error is, including its component parts, and what we can do to minimize its effect.

Comparison of spatial association approaches for landscape mapping of soil organic carbon stocks

A comparison of direct and indirect approaches for mapping SOC stocks from rule-based, multiple linear regression models applied at the landscape scale via spatial association. The final products for both strategies are high-resolution maps of SOC stocks (kg m‾²), covering an area of 122 km², with accompanying maps of estimated error. Although the indirect approach fit the spatial variation better and had a lower mean estimated error for the topsoil stock, the mean estimated error for the total SOC stock (topsoil + subsoil) was lower for the direct approach. The optimal approach would depend upon the intended use of the map.

CLORPT: Spatial Association in Soil Geography

From as early as 500 BCE, humans have recognized that some things vary together in space. This is essentially correlation, but the spatial aspect sometimes adds a special twist. Also, correlation requires evaluation of quantitative data, while this concept is not limited to quantitative characteristics. For example, Diophanes of Bithynia observed that “you can judge … Continue reading CLORPT: Spatial Association in Soil Geography

Digital classification of hillslope position

Classification of elevation rasters with this digital model of hillslope position represent base maps that can be used to (1) improve research on toposequences by providing explicit definitions of each hillslope element’s location, (2) facilitate the disaggregation of soil map unit complexes, and (3) identify map unit inclusions that occur due to subtle topographic variation.