Martin Rabenhorst

Martin Rabenhorst
University of Maryland, College Park | UMD, UMCP, University of Maryland College Park · Department of Environmental Science and Technology

PhD

About

163
Publications
24,344
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
3,150
Citations
Citations since 2016
38 Research Items
1382 Citations
2016201720182019202020212022050100150200250
2016201720182019202020212022050100150200250
2016201720182019202020212022050100150200250
2016201720182019202020212022050100150200250

Publications

Publications (163)
Article
Full-text available
Accurate prediction of soil organic carbon (SOC) at fine scales is frequently limited by data availability but fine-scale maps of soil properties are often of great importance for local agricultural land management and watershed processes assessment. Terrain attributes derived from elevation have been commonly used predictor variables in SOC mappin...
Article
Rhode River, a subestuary on the western shore of Chesapeake Bay, contains a diverse array of subaqueous soils that range from submerged paleosols to fine‐textured fluid soils and organic soils. A subaqueous soil survey was completed for the Rhode River subestuary by collecting bathymetric data, delineating landforms, and sampling and describing so...
Article
Full-text available
Iron-coated indicator of reduction in soils (IRIS) devices have been used for nearly two decades to help assess and document reducing conditions in soils, and official guidance has been approved for interpreting these data. Interest in manganese (Mn)-coated IRIS devices has increased because Mn oxides are reduced under more moderately reducing cond...
Article
Soil moisture and temperature are soil properties linked to climate and incorporated into Soil Taxonomy through the broad classes of moisture and temperature regimes. Although both are important variables in soil formation and land‐use, soil temperature regime (STR) is applied most often at the family level of Soil Taxonomy, while soil moisture reg...
Article
Full-text available
Indicator of Reduction In Soils (IRIS) technology is an important tool for identifying hydric soils, but it does not allow the user to monitor in real time. IRIS uses metal‐oxide coatings on a poly vinyl chloride surface that, under anaerobic conditions, are removed to varying degrees over a 30‐day incubation period, during which time the user is n...
Article
Efforts to utilize conventional soil maps in wetland conservation and restoration planning are often hampered by the coarse scale of the soil maps relative to the scale of restoration decisions, the spatial aggregation of soil components, and the difficulty in accounting for uncertainty in soil maps. The goal of this study was to explore the potent...
Article
The capillary fringe is a poorly defined tension‐saturated region with important influences on soil biogeochemistry. The goal of this research was to evaluate effects of the capillary fringe moisture gradient on biogeochemical processes, and to assess whether these processes are more similar to those of unsaturated or saturated zones. Effects were...
Article
Geographically isolated wetlands (GIWs) provide a portfolio of ecosystem services in low-gradient, Coastal Plain landscapes. Understanding how GIWs influence downstream waters is becoming increasingly important for conservation and management of these unique and important wetland ecosystems. Climatic conditions are known to be key drivers of water...
Article
Wetlands are valuable ecosystems protected under Section 404 of the Clean Water Act, and accurate delineation of wetlands is thus important for their continued preservation. The standard method for wetland delineation includes identifying hydric soils, based upon their distinctive hydromorphology that often includes gley colors, but in some cases s...
Article
Full-text available
The accurate and timely identification of soil morphological indicators of anaerobic conditions is critical for the proper documentation of hydric soils and prolonged soil saturation. Iron monosulfides (FeS) form under anaerobic conditions following complexation of Fe and reduced S to form insoluble, black to very dark grey (value ≤ 4, chroma ≤ 1)...
Article
Full-text available
The Agricultural Policy/Environmental eXtender (APEX) model has been widely used to assess changes in agrochemical loadings in response to conservation and management led by US Department of Agriculture (USDA). However, the existing APEX model is limited in quantification of wetland water quality functions. This study improved the current model cap...
Article
Full-text available
Problematic red parent material (PRPM) soils resist redox-induced color changes and development of redoximorphic features, posing a challenge to hydric soil and wetland identification. Previous studies suggested that color change resistance was a function of the mineralogical properties of hematite inherited from soil parent materials, but the unde...
Poster
Full-text available
The capillary fringe is a poorly defined and understood tension-saturated region of soil that has important influences on biogeochemical processes in upland and wetland soils. The primary goal of this research was to evaluate the effect of the moisture gradient in the capillary fringe on various biogeochemical processes, and to assess whether these...
Article
One of the many goals of wetland restoration is to promote the long-term storage of carbon (C) in the terrestrial biosphere. Unfortunately, soil C reservoirs in restored wetlands are slow to accumulate even after hydrology and plant communities are reestablished. Oftentimes wetland restoration changes the soil matrix and thus can dramatically alter...
Article
Full-text available
Hydric soil identification utilizes diagnostic morphologic features, including iron transformations, resulting from anaerobic conditions. However, soils derived from some red parent materials (RPM) fail to develop characteristic hydric soils morphologies, confounding hydric soil and wetland delineation. Laboratory and field methods addressing resis...
Article
Full-text available
Ecosystem services provided by depressional wetlands on the coastal plain of the Chesapeake Bay watershed (CBW) have been widely recognized and studied. However, wetland‐groundwater interactions remain largely unknown in the CBW. The objective of this study was to examine the vertical interactions of depressional wetlands and groundwater with respe...
Article
Geomorphic processes associated with coastal wetlands often result in high carbon accumulation rates and relatively large carbon stocks. Barrier islands are an important component of coastal ecosystems and freshwater and brackish wetlands on these islands provide an important habitat for a number of animal and plant species. However, organic carbon...
Article
Full-text available
The documentation of reducing conditions in soils is important in the study, monitoring, and delineation of hydric soils and wetlands. Over the last decade, IRIS (Indicator of Reduction In Soils) technology has moved from the periphery into common use in hydric soils studies. Their appeal has been their ease of use and their conceptual simplicity,...
Article
Following on earlier work that has shown the value of iron-based IRIS (Indicator of Reduction In Soils) technology, recent efforts have focused on developing a manganese-based IRIS coating. A synthesis procedure developed utilizing a high Na lactate to KMnO4 molar ratio followed by 3 d of dialysis, forms a crystalline birnessite that can be easily...
Article
Soil Taxonomy is one of the dominant soil classification systems in the world, but has undergone revisions on a regular basis since 1983. It is larger and some parts have become difficult to apply without considerable experience. Some pedologists that are not daily users (e.g. soil mappers) have called for a simpler version. The second edition of t...
Article
The 8th International Acid Sulfate Soils Conference presented examples and discussions for classification of ‘acid sulfate soils’ and related issues for ‘subaqueous soils’. When these soils are disturbed or exposed, the sulfides (predominantly pyrite) react with oxygen to produce sulfuric acid; soil materials that do this to a great extent are reco...
Article
High frequency in situ measurements of nitrate can greatly reduce the uncertainty in nitrate flux estimates. Water quality databases maintained by various federal and state agencies often consist of pollutant concentration data obtained from periodic grab samples collected from gauged reaches of a stream. Regression models, such as the LOAD ESTimat...
Article
Literature about the historical and current recognition of kinds, names and classification for, overall processes (sulfidization and sulfuricization) that form and conditions that induce the formation of potential, active and post-active acid sulfate soils are reviewed to set the stage for papers presented elsewhere in this special issue of Geoderm...
Article
Sulfide-containing soil materials can undergo a process known as sulfuricization if disturbed, triggering the production of sulfuric acid through the oxidation of Fe sulfides and causing environmental degradation. Several systems exist to classify these types of materials based on the level of environmental hazard that they may pose. Hypersulfidic...
Article
Agricultural drainage ditches function as first-order streams and affect nutrient management. Soil mesocosms from a ditch featuring a vertical (increasing upward) gradient in iron (Fe) and phosphorus (P) were subjected to hydraulic and soil treatments. These manipulations mimicked aspects of dredging and controlled drainage and inspected the soil r...
Article
Soil monoliths are powerful tools for soil education and for representing soils as they are found in the field. They preserve and display major soil features and are portable. The monolith herein described was collected from an active acid sulfate soil located near the western shore of the Chesapeake Bay in the Coastal Plain physiographic province...
Article
Saline wetlands have received limited attention from researchers and this neglect has often resulted in their degradation and limited conservation, and insufficient information to design conservation and management plans. Gallocanta Lake is a nature reserve of international importance for winter birds. The importance of the soil here, which support...
Article
During the last decade, Indicator of Reduction in Soils (IRIS) technology has been developed whereby polyvinyl chloride (PVC) devices coated with an Fe-oxide paint are inserted into the soil to document strongly reducing conditions. The IRIS devices are easy to use and interpret, are less prone to difficulties associated with other methods of asses...
Poster
Full-text available
Soil monoliths are powerful tools for soil education and for representing soils as they are found in the field. They preserve and display major soil features and are relatively portable (Belohlavy 1994). The monolith described in this poster was collected from an active acid sulfate soil located along a road cut near the Smithsonian Environmental R...
Article
Aquods commonly occur in wetland settings across a range of temperature regimes. Understanding their morphologies is critical to developing effective hydric soil indicators. In this study, we examined a range of wet Spodosols of the northeastern United States. We tested whether the red hues associated with wet spodic horizons are a function of humi...
Article
The Seventh Approximation emerged in 1960, and the first edition of Soil Taxonomy was published in 1975. Through the years, as intended in its original architecture, revisions have been made at all levels in the system. This has resulted in the addition of two new orders and a multitude of classes at other categorical levels. Four distinct and cont...
Article
Aerial extent of wetland ecosystems has decreased dramatically since precolonial times due to the conversion of these areas for human use. Wetlands provide various ecosystem services, and conservation efforts are being made to restore wetlands and their functions, including soil carbon storage. This Mid-Atlantic Regional USDA Wetland Conservation E...
Article
Soil characteristics and pedogenic processes are relatively unstudied on Holocene age barrier islands in the Mid-Atlantic region of the United States. The objective of this study was to assess how landform stability and hydrologic conditions (water availability) influenced pedogenesis in barrier island soils. Ten topographic transects were establis...
Conference Paper
The Rhode River estuary, a sub-estuary of the Chesapeake Bay, covers approximately 1000 ac of subaqueous landscape near Annapolis, MD. In freshwater and coastal subaqueous landscapes, the four soil forming processes of additions, removals, translocations, and transformations have been shown to operate, but the subaqueous soil concept had not yet be...
Article
Over the last century, North Carolina has seen a severe reduction in the percentage of wetlands and a rise in negative environmental impacts related to this loss. To counter these effects, efforts have been enacted to mitigate wetland loss and create new wetland areas. The objective of this study was to assess the impact of hydrological restoration...
Article
Hydric soils in Holocene-aged barrier island landscapes in the Mid-Atlantic region of North America lack morphologies typically associated with saturated and reducing conditions. Furthermore, many better drained (nonhydric) soils have low chroma colors due to parent material effects, making identification and delineation of wetlands problematic. Ou...
Article
Standardized color charts with the Munsell notation have been routinely used by soil scientists for >60 yr. In recent decades, modern technologies (such as digital colorimeters) have permitted further precision in the measurement of soil colors. Preliminary digital measurements of soil color chips indicated some notable discrepancies between report...
Article
Delmarva Bays are depressional wetlands that are elliptical in shape with sandy rims, and occur mainly in the central portion of the Delmarva Peninsula within the Mid-Atlantic United States. Situated in a region with abundant agriculture, Delmarva Bays and other wetlands may enhance water quality by reducing nutrient and sediment levels in local wa...
Article
Biogeochemistry is the scientific discipline that addresses the biological, chemical, physical, and geological processes that govern the composition of the natural environment, with particular emphasis placed on the cycles of chemical elements critical to biological activity. Biogeochemical assays may measure a specific elemental pool, determine th...
Article
Color is one of the most obvious properties of soils and is utilized in many soil evaluation strategies. Color data are usually documented using Munsell notation of hue, value, and chroma, with the latter two parameters normally documented to the nearest whole unit. Soil colors with chroma less than or equal to 2 are particularly important in soil...
Conference Paper
Within the past 20 years, there has been a shift in wetland conservation efforts past protection of existing wetlands to the restoration of previously disturbed wetlands. Through the Wetland Reserve Program, the USDA-NRCS has restored over 2.6 million acres of private land intending that they be functionally equivalent to natural wetlands. The prim...
Article
There are some unique soils in central Maryland with extremely high quantities of Mn and Fe oxides, up to 141 g kg(-1) Mn and 169 g kg(-1) Fe (extracted by dithionite-citrate-bicarbonate). Such high quantities of Mn oxides have pigmented the entire soil matrix black in subsoil horizons. Previously, little was known about the extent of these mangani...
Article
Field practitioners of wetland and soil science are called on to estimate the percentage of soil organic C (SOC) to classify soil materials as mineral, mucky-modified mineral, or organic. The primary objective of this study was to determine how well field scientists were able to estimate SOC content and properly classify soil materials. Two paralle...
Article
The recent use of IRIS (indicator of reduction in soils) tubes by wetland scientists and approval of their use by the National Technical Committee for Hydric Soils has required some simple means for quantifying paint removed from the tubes. The cylindrical shape of the tubes has generally made scanning or other automated processes difficult. Visual...
Article
Manganese is normally a trace element in soils, but it is important due to its effects on soil chemistry and morphology. There are rare, Mn-rich soils in the Eastern Piedmont of the USA that have not been previously studied. The morphology, mineralogy, and chemical and physical properties of these manganiferous soils were documented in order to bet...
Article
Indicator of Reduction In Soils (IRIS) tubes have recently been developed for assessing reducing soil conditions. Under saturated and reducing conditions, the Fe oxide paint becomes reduced and soluble and is partially stripped from the tubing. In normal field applications, the proportion of paint removed from the tubes is estimated visually, simil...
Article
In estuarine systems, naturally occurring soluble S(2-) is an indicator of anaerobic decomposition by the SO(4)(2-) reduction pathway and can, at high concentrations, be detrimental to plant communities. Depth distributions of soluble S(2-) in marsh pore water are typically measured using either equilibrium dialysis samplers (peepers) or pore water...
Article
A conceptual framework is presented to portray how Fe, S and other elements (Ca, Si, K) are geologically and pedologically cycled between minerals that are formed and are stable in land-based aerobic environments and those that are formed and are stable in anaerobic sea-based environments. Foremost among the elements discussed are Fe and S, which c...
Article
Researchers studying the chemistry of soil systems may be interested in documenting the oxidation-reduction potential (Eh) for a variety of purposes, and this is often accomplished by measuring the Eh using platinum (Pt) electrodes in conjunction with a reference electrode and a voltmeter. It has been shown that Eh values obtained when using high r...
Article
Full-text available
Soil redox potentials (Eh) are commonly measured and operationally defined using platinum (Pt) electrodes, but there are variations in the methodology and instrumentation for measuring the associated voltages that may lead to imprecise and inaccurate estimates of oxidation-reduction intensity in the soil environment. Most field measurements of Eh a...
Article
Full-text available
Oxidation-reduction (redox) reactions regulate many chemical processes that occur in soils. Saturation, C availability, microorganisms, and temperature dictate the rate and type of redox reactions that will occur. The measurement of redox potential enables researchers to predict the stability of redox-sensitive species, such as Fe oxides. We determ...
Article
Full-text available
Reducing conditions in soils can be documented by the voltage measured between Pt and reference electrodes (Eh) or by using dyes like α,α(-dipyridyl for identifying reduced species (such as Fe 2+ ). Indicator of Reduction in Soils (IRIS) tubes have been recently introduced as an alternative approach for documenting reducing conditions in soils, whe...
Article
Recently, a new technology known as indicator of reduction in soils (IRIS) has emerged for documenting reducing conditions in soils. An iron (Fe) oxide paint is applied to polyvinyl chloride tubing that is subsequently placed within the soil. Under reducing conditions, the Fe oxides gain electrons, become soluble, and are stripped from the tubing....
Article
Full-text available
Some materials in drainage ditches that have traditionally been referred to and studied as sediments may be soils. In this study, we described and characterized materials found within agricultural ditches at the University of Maryland Eastern Shore Research Farm (Princess Anne, MD). Sixty-nine profiles were described in 10 ditches ranging in length...
Conference Paper
Concerns over the mitigation of global warming and the impacts of rising sea levels caused by global warming have focused attention on tidal wetlands. The restoration and management of tidal wetlands may allow such areas to sequester carbon, helping to mitigate global warming, while the accumulation of organic materials may help prevent the marshes...
Article
The Marlboro Clay is a late Paleocene/early Eocene geologic formation that outcrops in significant portions of Prince George's County, Maryland. The formation exhibits slope instability and is unsuitable for most building structures. In this study, we describe and characterize the mineralogical and shrink-swell properties of soils formed in Marlbor...
Article
Various circumstances in wetland delineation or mitigation strate- gies require the documentation of reducing conditions in soils. An in- novative approach for assessing reduction in soils known as Indicator of Reduction in Soils (IRIS) has been recently introduced. IRIS tubes aremanufacturedbycoatingpolyvinylchloride(PVC)pipewithapaint prepared fr...
Article
Full-text available
Research and management of wetlands often requires the documentation of reducing soil conditions. Documentation of reduction in soils by measuring oxidation-reduction (redox) potentials using Pt electrodes is often difficult because of the time and cost involved in employing these techniques. This study evaluated a new procedure called Indicator of...
Article
Full-text available
Research and management of wetlands often requires the docu- mentation of reducing soil conditions. Documentation of reduction in soils by measuring oxidation-reduction (redox) potentials using Pt electrodes is often difficult because of the time and cost involved in employing these techniques. This study evaluated a new proce- dure called Indicato...
Article
Temperature effects on soil microbiological activity were well-documented in the first half of the 20th century, and many workers recognized that most (mesophyllic) soil microbes became relatively inactive at temperatures below 5° to 10°C. The term biologic zero first was published in the soil science literature in the first edition of Soil Taxonom...
Article
Full-text available
For soils to be considered hydric, they must demonstrate both saturation and anaerobic conditions in the upper part of the soil. Although several technologies are available for monitoring of soil water tables, documentation of reducing conditions is more problematic. This has led to recent interest in the use of IRIS (indicator of reduction in soil...
Article
Soil microbial properties are known to exhibit high spatial and temporal variability, which can hinder our understanding of the effects of agricultural management on soil microbial activities, populations and communities. However, if this variability is explicitly considered in soil sampling schemes, experimental results can help us better understa...
Article
The unoxidized portions of Upper Cretaceous (UC) regolith in Maryland's inner Coastal Plain have been observed to contain significant amounts of microscopic pyrite. The exposure of these sulfide-bearing sediments initiates rapid acid sulfate weathering processes resulting in extremely acidic soils and runoff. Previous anecdotal observations have sh...
Article
Two transects were established across submerging coastal landscapes in Dorchester County, Maryland. Extensive sampling protocol was performed along the submerging upland tidal marsh soils to model C sequestration. Coastal marsh soils are accreting vertically and migrating laterally over the low-lying forest soils to keep pace with sea-level rise. T...