Redefining the fragipan to improve field recognition and land use relevance

Drohan, Patrick J.; Thompson, James A.; Lindbo, David; Beaudette, Dylan; Dadio, S.

doi:10.1002/saj2.20098

Cited by 3 publications

(2 citation statements)

References 44 publications

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“…Fragipans are observed globally, including in the United States, with an estimated coverage of ∼970,000 km 2 (Bockheim & Hartemink, 2013; Grossman & Carlisle, 1969), Italy (Certini et al., 2007; Marsan & Torrent, 1989), Poland (Szymański et al., 2012), and New Zealand (Smalley & Fagg, 2015). Fragipans are commonly formed under forested vegetation (Franzmeier et al., 1989) and in transported parent materials, including loess, alluvium, colluvium, and glacial till (Bockheim & Hartemink, 2013; Ciolkosz & Waltman, 1995; Drohan et al., 2020). Fragipan horizon morphology is variable (Bockheim & Hartemink, 2013; Soil Survey Staff, 2022), but typically exhibits dense, brittle, reddish structural units (e.g., prisms and subangular blocks) that are separated by bleached gray zones or seams.…”

Section: Introductionmentioning

confidence: 99%

Mineralogical differences between seam and prism material in loess‐derived fragipans in western Kentucky

Shepard,

Somerville,

Matocha

et al. 2024

Soil Science Soc of Amer J

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Fragipan horizons are common diagnostic subsurface features typically identified by their dense, brittle nature under field conditions. Fragipan horizons are often hypothesized to contain various silicate bonding agents, including phyllosilicates, amorphous aluminosilicates/silica, and silica sorbed to iron oxyhydroxides. However, the association of silica (Si) with other minerals in these horizons remains uncertain. To fill this knowledge gap, we sampled the prism and seam material of four loess‐derived fragipan horizons in western Kentucky. We characterized and compared the clay mineral composition of the prism and seam material using X‐ray diffraction (XRD), selective extractions, and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Fragipan prism and seam material exhibited a mixed clay mineralogy comprised of vermiculite, mixed layer minerals (hydroxyl‐interlayered vermiculite), illite, kaolinite, and quartz. We identified goethite in fragipan prisms in much greater quantities when compared to seam material, confirmed by both XRD and DRIFTS and corroborated by higher dithionite‐extractable iron in prisms. DRIFT spectra showed a peak near 3180 cm−1 assigned to OH‐stretching mode of goethite, which was prominent in prism materials. Goethite 110 XRD peak positions were negatively correlated to dithionite‐extractable aluminum (Al) and Si content of the prism material, which may suggest greater Si sorbed to the surfaces of Al‐substituted goethite. These results demonstrate the potential importance of Al‐substituted goethite in fragipan prisms and provide insight about possible associations with Si.

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Section: Introductionmentioning

confidence: 99%

Mineralogical differences between seam and prism material in loess‐derived fragipans in western Kentucky

Shepard,

Somerville,

Matocha

et al. 2024

Soil Science Soc of Amer J

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“…Fragipan brittleness in the wet state, coupled with hardness when dry, narrows the range of functions and ecosystem services exerted by soils and impacts hydropedological and mechanical behavior (e.g. Franzmeier et al, 1989;Drohan et al, 2020). Brooks et al (2012) remarked that fragipans have low drainable porosity, i.e.…”

Section: Introductionmentioning

confidence: 99%

Atterberg limits fail in recognizing fragipan horizons

Stanchi

Negri

D’Amico

et al. 2021

CATENA

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Fragipan is a subsurface soil horizon characterized by high bulk density, coupled with an abundance of fine, blind pores. We hypothesized that this distinctive porosity pattern could affect the Atterberg limits, with significant deviations from those of otherwise comparable soil horizons. Additionally, longer pre-wetting times might be needed to determine the liquid and plastic limits in fragipan, due to restrictions in water movements. Based on these hypotheses, our research focused on (1) assessing the most suitable fragipan-specific sample preparation time for liquid and plastic limit determination; (2) evaluating if the Atterberg limits reflect the presence of fragic properties; (3) exploring the relationships between Atterberg limits and other relevant soil properties through Artificial Neural Networks. Fragipan horizons (F) had a slightly higher liquid limit, much higher bulk density, and specific surface area than nonfragipan (NF). The plastic limit was however comparable for F and NF. Thus, fragipans had a larger interval of plasticity, which is in contrast with slaking tests and wellknown field evidence. Despite the expected differences between F and NF, three hours' pre-wetting was enough for all samples. This might be due to the size fraction used in the analysis, more sensitive to collapse upon water saturation than bigger clods. Atterberg limits did not help in discriminating F from NF, despite the relevant differences in other soil physical properties. Neural Networks showed that the transition from the plastic to the liquid state was mainly driven by texture and specific surface area, while the plasticity interval was mainly affected by the bulk density. These results provided further insights into the mechanical properties of fragipan horizons.

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Influence of Annual Ryegrass (Lolium multiflorum) as Cover Crop on Soil Water Dynamics in Fragipan Soils of Southern Illinois, USA

Chatterjee,

Dinnes,

Olk

et al. 2024

Soil Systems

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Fragipans are dense subsurface soil layers that severely restrict root penetration and water movement. The presence of shallow fragipan horizons limits row crop production. We hypothesized that the roots of cover crop might improve soil physiochemical properties and biological activity, facilitating drainage and increasing effective soil depth for greater long-term soil water storage. To evaluate annual ryegrass as one component of a cover crop (CC) mix for promoting the characteristics and distribution of soil water, on-farm studies were conducted at Marion and Springerton in southern Illinois, USA. Soil samples were collected at 15 cm increments to 60 cm (Marion) and 90 cm (Springerton) depths during the fall of 2022. Both sites had low total soil carbon and nitrogen contents and acidic soil pH (≤6.4). A soil water retention curve was fitted using the van Genuchten equation. At Springerton, the CC treatment increased saturated (thetaS) and residual (thetaR) soil water contents above those of the no cover crop (NCC) at the 60–75 cm and 75–90 cm depths. Changes in volumetric soil water content were measured using a multi-depth soil water sensor for the Springerton site during late July to early August of the soybean growing phase of 2022; NCC had higher soil water than CC within the 0–15 cm depth, but CC had higher soil water than NCC at the 30–45 cm depth. These findings indicate that cover crop mix has the potential to improve soil water movement for soils with restrictive subsoil horizon, possibly through reducing the soil hydraulic gradient between the surface and restrictive subsurface soil layers.

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Redefining the fragipan to improve field recognition and land use relevance

Cited by 3 publications

References 44 publications

Mineralogical differences between seam and prism material in loess‐derived fragipans in western Kentucky

Mineralogical differences between seam and prism material in loess‐derived fragipans in western Kentucky

Atterberg limits fail in recognizing fragipan horizons

Influence of Annual Ryegrass (Lolium multiflorum) as Cover Crop on Soil Water Dynamics in Fragipan Soils of Southern Illinois, USA

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