Subaqueous soils: Pedogenesis in a submersed environment.

ABSTRACT and sediment parameters is difficult to determine. To apply a new approach, a pedological approach, it is Proposals for the inclusion of permanently submersed materials necessary to demonstrate that shallow water sediments in soil taxonomic systems have periodically been put forth since some can be described by a pedological paradigm. time in the mid 1800s. The proposals were largely conceptual in nature, relying more on subjective reasoning rather than analytical and field Since the inception of pedological research, debate data. Advances in computer and global positioning technology, and concerning the inclusion of subaqueous materials in soil the continuing development of the discipline of pedology provided taxonomic systems has arisen periodically (v.Post, 1862; the opportunity to examine shallow water estuarine sediments within a pedological framework. Morphological and analytical data from 85 The question at the center of the debate seems to be 1.5-to 2.0-m profiles from Sinepuxent Bay, Maryland, indicate that related to the concepts of the "upper limit" of soil and the four pedogenic processes of additions, losses, transformations

Manganese-coated IRIS to document reducing soil conditions

Iron-coated indicatorof 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 conditions than iron (Fe) oxides (which require strongly reducing conditions), such that they are expected to be better proxies for some important ecosystem services like denitrification. However, only recently has the necessary technology become available to produce Mn-coated IRIS, and the need is now emerging for guidance in interpreting data derived from Mn IRIS. Ninety-six data sets collected over a 2-yr period from 40 plots at 18 study sites among eight states were used to compare the performance of Mn-coated IRIS with Fe-coated IRIS and to assess the effect of duration of saturation and soil temperature as environmental drivers on the reduction and removal of the oxide coating. It appears that the current threshold prescribed by the National Technical Committee for Hydric Soils for Fe-coated IRIS is appropriate for periods when soil temperatures are warmer (\u3e11 °C), but is unnecessarily conservative when soil temperatures are cooler (5–11 °C). In contrast, Mn-coated devices are particularly useful early in the growing season when soil temperatures are cool. Our data show that when using a threshold of 30% removal of Mn oxide coatings there is essentially 100% confidence of the presence of reducing soil conditions under cool (\u3c11 °C) conditions

Application and evaluation of a subaqueous soil-landscape conceptual model in the West River subestuary, Maryland

A soil-landscape conceptual model developed in the Rhode River subestuary of Maryland was applied to create a soil survey for the adjacent West River subestuary. The survey for the West River subestuary was completed before samples were collected there to evaluate the soil-landscape conceptual model used to generate the soil survey. The West River subestuary was then sampled along transects that crossed soil map units to compare observed soil taxa with predicted soil taxa. Observed transect samples were classified and scored based on their similarity to predicted taxa in soil map units. These data were resampled via a bootstrapping method to determine if the predictions of the West River subestuary soil survey were significantly different from random predictions. Significant information was provided by the survey, and therefore by the soil-landscape conceptual model used to generate it.https://doi.org/10.1002/saj2.2049

Soil color and US Northeast aquods

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 humic (HA) and fulvic acids (FA) or Fe, and addressed questions related to hydric soil indicators, horizon designation, and soil classification. Only two of the 11 seasonally saturated Spodosols met current criteria for Aquods. Almost all of the 24 Bh, Bhs, or Bhsm horizons had 3 to 10 times more ammonium oxalate extractable Al than Fe (mean Fe was \u3c0.15%), yet only three pedons met the current criteria for Al great groups. We found no consistently applied color or sesquioxide content criteria for separating Bh from Bhs horizons. These results suggest that criteria for horizon designation and classification of Aquods need to be reconsidered. There were no relationships between extractable Fe and hue (p = 0.50). Weak correlation coefficients (-0.40 and -0.39; p = 0.051 and 0.057) between hue and FA and HA suggest little support for red hues being primarily a function of HA or FA. The significant relationship between Al and hue (-0.46; p = 0.025) and the strong correlation between Al and both HA and FA (0.87 and 0.86; p \u3c 0.001) suggest a possible interaction between Al and the humic substances resulting in redder hues. We found more than twice as much HA in the spodic horizons as FA and concluded that FA is the precursor of HA in US Northeast spodic horizons

Impacts of fundamental changes to Soil Taxonomy

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 the Illustrated Guide to Soil Taxonomy serves as a model for enhanced teaching purposes that can be used by others besides trained soil scientists. In 2014, a task force was created to develop a set of proposed improvements to Soil Taxonomy. Guiding principles were established to assist in the development of proposals to increase the use of Soil Taxonomy, minimise the impact on the existing soil survey and soil science division programs, and move toward harmonisation of definitions with other classification systems, such as the WRB and South African systems. Initially, 15 proposals have been listed. Examples of a simplified mollic epipedon and addition of several new soil orders are discussed. Accepted proposals will contribute toward the third edition of Soil Taxonomy. The impact will be easier collaboration between soil scientists in countries that use Soil Taxonomy and better communication with other professionals

Impacts of fundamental changes to Soil Taxonomy

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 the Illustrated Guide to Soil Taxonomy serves as a model for enhanced teaching purposes that can be used by others besides trained soil scientists. In 2014, a task force was created to develop a set of proposed improvements to Soil Taxonomy. Guiding principles were established to assist in the development of proposals to increase the use of Soil Taxonomy, minimise the impact on the existing soil survey and soil science division programs, and move toward harmonisation of definitions with other classification systems, such as the WRB and South African systems. Initially, 15 proposals have been listed. Examples of a simplified mollic epipedon and addition of several new soil orders are discussed. Accepted proposals will contribute toward the third edition of Soil Taxonomy. The impact will be easier collaboration between soil scientists in countries that use Soil Taxonomy and better communication with other professionals

Mn-Coated IRIS to Document Reducing Soil Conditions

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 conditions than iron (Fe) oxides (which require strongly reducing conditions), such that they are expected to be better proxies for some important ecosystem services like denitrification. However, only recently has the necessary technology become available to produce Mn-coated IRIS, and the need is now emerging for guidance in interpreting data derived from Mn IRIS. Ninety-six data sets collected over a 2-yr period from 40 plots at 18 study sites among eight states were used to compare the performance of Mn-coated IRIS with Fe-coated IRIS and to assess the effect of duration of saturation and soil temperature as environmental drivers on the reduction and removal of the oxide coating. It appears that the current threshold prescribed by the National Technical Committee for Hydric Soils for Fe-coated IRIS is appropriate for periods when soil temperatures are warmer (\u3e11 °C), but is unnecessarily conservative when soil temperatures are cooler (5–11 °C). In contrast, Mn-coated devices are particularly useful early in the growing season when soil temperatures are cool. Our data show that when using a threshold of 30% removal of Mn oxide coatings there is essentially 100% confidence of the presence of reducing soil conditions under cool (\u3c11 °C) conditions

Macro and microscopic visual imaging tools to investigate metal reducing bacteria in soils

39 Pags.- 9 Figs.- 3 Tabls. The definitive version is available at: https://acsess.onlinelibrary.wiley.com/journal/14350661Indicator 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 polyvinyl chloride surface that, under anaerobic conditions, are removed to varying degrees over a 4‐wk incubation period, during which time the user is not cognizant of the outcome. We document the viability of an alternative IRIS approach using clear‐IRIS tubes, made from cellulose acetate butyrate, that can be continuously monitored in situ with a Wi‐Fi–enabled video camera. This work shows that IRIS and clear‐IRIS tubes are statistically equivalent. Manganese‐oxide coated clear‐IRIS tubes correlated well with IRIS tubes (r = .79) and ferrous‐oxide had a high correlation (r = .97). A time‐series analysis showed that rain‐driven soil saturation induced IRIS metal‐oxide reduction and controlled the rate. Clear‐IRIS tubes enable remote sensing of metal‐oxide removal over time.This work was supported by the USDA National Institute of Food and Agriculture, Hatch Project Number: MD‐ENST‐7741. C.C. and B.L. were funded by the project ERANETMED3‐173 AQUASALT (Spanish Government grant PCI2018‐092999).Peer reviewe

Soil taxonomy proposals for acid sulfate soils and subaqueous soils raised by the 8th International Acid Sulfate Soils Conference\u3csup\u3e§\u3c/sup\u3e

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 recognised as ‘sulfidic materials’ in Soil Taxonomy. Soil Taxonomy describes physical and chemical properties and thresholds for incubation of sulfidic materials for acidification, and has developed definitions for features and materials commonly seen in these soils. However, based on discussions and examples from field tours the conference has several proposals to modify and add to existing definitions, such as adding new subgroups, defining sulfuric materials and editing the definition of the sulfuric horizon. These changes are centred on improving the interpretative value of taxa in Soil Taxonomy as well as use and management recommendations and their value in soil survey products