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  • 2015-2019  (6)
  • Geography  (6)
  • RA 4845  (6)
  • 1
    Online Resource
    Online Resource
    Determining Normal Precipitation Ranges for Hydric Soil Assessments
    Wiley ; 2019
    In:  Soil Science Society of America Journal Vol. 83, No. 2 ( 2019-03), p. 503-510
    Details
    In: Soil Science Society of America Journal, Wiley, Vol. 83, No. 2 ( 2019-03), p. 503-510
    Abstract: Core Ideas Normal rainfall ranges are best defined by the 30th and 70th percentiles of historic data. Mean ± SD produces a normal rainfall range twice as large as that of percentiles. Mean ± SD normal rainfall will cause some upland soils to be classified as hydric soils. Water table data collected for hydric soil and wetland identification studies require supporting analysis of rainfall normality. Water table measurements made after periods when precipitation is within a normal range are believed to represent long‐term trends, whereas data collected following periods of abnormally high precipitation represent rare events, potentially resulting in erroneous hydric soil determinations. The USDA‐NRCS currently uses two different methods to assess normal precipitation ranges; both have been used to assess hydric soils. This study compared methodologies that identify normal precipitation periods by using: (i) the range defined by the 30th and 70th percentiles observed within a 30‐yr period [i.e., the Climate Analysis for Wetlands Tables (WETS) method] and (ii) long‐term monthly mean precipitation ± one SD (i.e., the U.S. Soil Taxonomy method). Comparisons were made for 30 geographically diverse locations and soil moisture regimes. The results demonstrated that the U.S. Soil Taxonomy method yielded normal precipitation ranges approximately twice as large as those from the WETS method. As a result, the U.S. Soil Taxonomy method precluded the occurrence of drier than normal conditions in many instances and displayed increased sensitivity to infrequent high rainfall events. Three case studies evaluated the implications of method selection on hydric soil identification, demonstrating that the U.S. Soil Taxonomy method identified normal conditions more frequently than the WETS method. As a result, the adoption of the WETS method, which accounts for the non‐normal distribution of precipitation data, as the sole method to determine normal precipitation periods for hydric soil assessment is recommended.
    Type of Medium: Online Resource
    ISSN: 0361-5995 , 1435-0661
    URL: Article
    DOI: 10.2136/sssaj2018.09.0333
    RVK:
    RA 4845
    Language: English
    Publisher: Wiley
    Publication Date: 2019
    detail.hit.zdb_id: 241415-6
    detail.hit.zdb_id: 2239747-4
    detail.hit.zdb_id: 196788-5
    detail.hit.zdb_id: 1481691-X
    SSG: 13
    SSG: 21
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  • 2
    Online Resource
    Online Resource
    Effects of Aporrectodea Caliginosa on Soil Hydraulic Properties and Solute Dispersivity
    Wiley ; 2015
    In:  Soil Science Society of America Journal Vol. 79, No. 3 ( 2015-05), p. 838-847
    Details
    In: Soil Science Society of America Journal, Wiley, Vol. 79, No. 3 ( 2015-05), p. 838-847
    Abstract: Earthworms have historically been absent from dryland agricultural fields in eastern Colorado, but their invasion or purposeful introduction may affect water retention and plant nutrient availability in soil. The objective of this study was to determine the effect of Aporrectodea caliginosa on hydraulic properties and solute dispersivity in soil from eastern Colorado (Adena [Ustic Paleargid]–Colby [Aridic Ustorthents] complex) that was amended with biosolids. Columns of repacked soil (50 cm in depth) were incubated with or without A. caliginosa for a period of 16 wk, after which columns were divided into 15‐cm depth increments to determine soil–water retention curves and solute breakthrough curves (BTCs) under unsaturated and saturated conditions. Aporrectodea caliginosa and their burrows and casts altered soil water retention curves in the top 30 cm of the soil, where A. caliginosa were most active. Earthworms also affected BTCs within the top 30 cm of soil resulting in an approximately 35‐fold increase in solute dispersivity under saturated flow conditions and a 4‐ to 10‐fold increase with unsaturated flow conditions. Overall, A. caliginosa increased soil residual water content by 33 to 41% and altered soil physical properties so that water flow became more tortuous, solute dispersion increased under saturated and unsaturated conditions, and soil drained over a larger range of tensions. In conclusion, A. caliginosa has the potential to reduce upward losses of water, increase water retention, and increase dispersion of agricultural chemicals applied to the soil surface.
    Type of Medium: Online Resource
    ISSN: 0361-5995 , 1435-0661
    URL: Article
    DOI: 10.2136/sssaj2014.07.0290
    RVK:
    RA 4845
    Language: English
    Publisher: Wiley
    Publication Date: 2015
    detail.hit.zdb_id: 241415-6
    detail.hit.zdb_id: 2239747-4
    detail.hit.zdb_id: 196788-5
    detail.hit.zdb_id: 1481691-X
    SSG: 13
    SSG: 21
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  • 3
    Online Resource
    Online Resource
    Understanding the Inhibition of Color Change in Problematic Red Parent Material Hydric Soils
    Wiley ; 2019
    In:  Soil Science Society of America Journal Vol. 83, No. 3 ( 2019-05), p. 838-847
    Details
    In: Soil Science Society of America Journal, Wiley, Vol. 83, No. 3 ( 2019-05), p. 838-847
    Abstract: Core Ideas Problematic red parent material (PRPM) soils lack typical hydromorphological characteristics. Hematite mineralogy was suspected to limit redox‐induced color change in PRPM soils, but mechanisms were previously unknown. Physical occlusion of Fe oxides in fine (silt and sand sized) lithic fragments did not induce color change resistance. Significant Al for Fe substitution in hematite of PRPM soils was not observed, excluding that mechanism. The large size of hematite crystals limits Fe reduction resulting in color change resistance in PRPM soils. 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 underlying cause of the phenomenon has remained uncertain. In this study, several hypotheses (i.e., physical occlusion, Al substitution, and crystal size) were investigated to explore the mechanism of PRPM soil color change resistance. The physical occlusion hypothesis was assessed by comparing Color Change Propensity Index (CCPI) values between size fractions for both PRPM and non‐PRPM soils. Persistence of color change resistance (low CCPI) in the finest (clay) fractions of all PRPM soils resulted in removing the physical occlusion hypothesis from consideration. Substitution of Al for Fe in hematite was compared between PRPM and non‐PRPM clay fractions by observing X‐ray diffraction (XRD) peak shifts. Substitution of Al in hematite remained low for the PRPM samples (mean 0.8 mol%), compared with the non‐PRPM (mean 6.8 mol%) suggesting that Al substitution is not the cause of observed color change resistance. Finally, mean hematite crystallite size was evaluated using Scherrer equation calculations. Mean hematite crystallite size in PRPM soils was significantly larger than non‐PRPM soils ( P = 0.0039), suggesting that color change resistance and the PRPM soil phenomenon are derived from the large size of hematite crystals.
    Type of Medium: Online Resource
    ISSN: 0361-5995 , 1435-0661
    URL: Article
    DOI: 10.2136/sssaj2018.10.0390
    RVK:
    RA 4845
    Language: English
    Publisher: Wiley
    Publication Date: 2019
    detail.hit.zdb_id: 241415-6
    detail.hit.zdb_id: 2239747-4
    detail.hit.zdb_id: 196788-5
    detail.hit.zdb_id: 1481691-X
    SSG: 13
    SSG: 21
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  • 4
    Online Resource
    Online Resource
    Application of α,α'‐dipyridyl dye for hydric soil identification
    Wiley ; 2017
    In:  Soil Science Society of America Journal Vol. 81, No. 3 ( 2017-05), p. 654-658
    Details
    In: Soil Science Society of America Journal, Wiley, Vol. 81, No. 3 ( 2017-05), p. 654-658
    Abstract: Core Ideas The α,α'‐dipyridyl dye displayed a ferrous iron detection limit of 0.31mg L −1 . Liquid α,α' dipyridyl dye and indicator test strips exhibited similar reactivity. Light and heat exposure led to potential α,α'‐dipyridyl dye degradation. The α,α'‐dipyridyl dye provides a tool for hydric soil and wetland identification. Chemical dyes, including α,α'‐dipyridyl, can be used to identify ferrous iron in hydric soil studies and aid in conducting wetland delineations. Indicator test strips containing α,α'‐dipyridyl have been developed; however, limited data addresses the reliability of indicator test strips and questions remain regarding potential degradation of α,α'‐dipyridyl in liquid and paper formulations. Laboratory studies found ferrous iron detection limits of 0.31 mg L −1 using both liquid and indicator test strips. The liquid dye and indicator test strips displayed similar reactivity in five soils under simulated field conditions. Results suggest that indicator test strips provide a useful tool for ferrous iron detection across a range of soil conditions. Degradation studies indicate that both liquid dye and indicator strips were impacted by light and heat exposure, with a loss of reactivity observed within as few as 3 d under extreme conditions. Maintaining both liquid dye and indicator strips in cool, dark conditions and testing reactivity with laboratory solutions will ensure the reliability of α,α'‐dipyridyl results.
    Type of Medium: Online Resource
    ISSN: 0361-5995 , 1435-0661
    URL: Article
    DOI: 10.2136/sssaj2016.12.0431
    RVK:
    RA 4845
    Language: English
    Publisher: Wiley
    Publication Date: 2017
    detail.hit.zdb_id: 241415-6
    detail.hit.zdb_id: 2239747-4
    detail.hit.zdb_id: 196788-5
    detail.hit.zdb_id: 1481691-X
    SSG: 13
    SSG: 21
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  • 5
    Online Resource
    Online Resource
    Dolomite and Micronutrient Fertilizer Affect Phosphorus Fate in Pine Bark Substrate used for Containerized Nursery Crop Production
    Wiley ; 2019
    In:  Soil Science Society of America Journal Vol. 83, No. 5 ( 2019-09), p. 1410-1420
    Details
    In: Soil Science Society of America Journal, Wiley, Vol. 83, No. 5 ( 2019-09), p. 1410-1420
    Abstract: Core Ideas Addition of dolomite or micronutrients reduced leachate‐P from bark‐based substrates. Orthophosphate‐P from controlled‐release fertilizer contributed 74 to 86% of TDP. Dolomite reduced fertilizer orthophosphate‐P in leachate by 〉 50%. MnHPO 4 and Ca 5 (PO 4 ) 3 (OH) were dominant modeled solid‐phase species in leachate. Addition of dolomite and micronutrient amendments to bark may be considered a BMP. Dolomite and a micronutrient fertilizer are routinely incorporated into a pine bark‐based soilless substrate when producing containerized nursery crops, yet the effect of these amendments on phosphorus (P) is not well understood. The objective of this research was to determine the effect of dolomite and micronutrient fertilizer amendments on P partitioning among four P fractions (i.e., orthophosphate‐P [OP], non‐orthophosphate dissolved P [NODP] , total dissolved P [TDP], and particulate P [PP] ) and to model potential P species in leachate of pine bark substrate. Amendment treatments incorporated into bark at experiment initiation included (1) a control (no fertilizer, dolomite, or micronutrient fertilizer), (2) controlled‐release fertilizer (CRF), (3) CRF and dolomite, (4) CRF and micronutrient fertilizer, or (5) CRF, dolomite, and micronutrient fertilizer. Phosphorus fractions in leachate of irrigated pine bark columns were determined at eight sampling times over 48 days. Amending pine bark with dolomite and micronutrient fertilizer reduced leachate OP concentrations by 70% when averaged across sampling dates primarily due to retention of OP in the substrate by dolomite. The NODP fraction was unaffected by amendments, and the response of TDP was similar to that of OP. Particulate P was present throughout the study and was strongly correlated particulate Fe and DOC concentrations. Visual MINTEQ indicated MnHPO 4 and Ca 5 (PO 4 ) 3 (OH) were consistently saturated with respect to their solid phase in treatments containing CRF. Results of this study suggest amending pine bark with dolomite and micronutrients is a best management practice for reducing P leaching from containerized nurseries.
    Type of Medium: Online Resource
    ISSN: 0361-5995 , 1435-0661
    URL: Article
    DOI: 10.2136/sssaj2018.12.0493
    RVK:
    RA 4845
    Language: English
    Publisher: Wiley
    Publication Date: 2019
    detail.hit.zdb_id: 241415-6
    detail.hit.zdb_id: 2239747-4
    detail.hit.zdb_id: 196788-5
    detail.hit.zdb_id: 1481691-X
    SSG: 13
    SSG: 21
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  • 6
    Online Resource
    Online Resource
    Alternate Wetting and Drying Decreases Methylmercury in Flooded Rice ( Oryza sativa ) Systems
    Wiley ; 2018
    In:  Soil Science Society of America Journal Vol. 82, No. 1 ( 2018-01), p. 115-125
    Details
    In: Soil Science Society of America Journal, Wiley, Vol. 82, No. 1 ( 2018-01), p. 115-125
    Abstract: Core Ideas We studied how alternate wetting and drying (AWD) water management effects methylmercury (MeHg) dynamics in rice fields. Alternate wetting and drying reduced MeHg concentrations in soil, water, and rice grain. Iron speciation indicated that AWD oxidized the soil and regenerated electron acceptors. Rice yield did not differ between AWD and the control over 4 yr. In flooded soils, including those found in rice ( Oryza sativa L.) fields, microbes convert inorganic Hg to more toxic methylmercury (MeHg). Methylmercury is accumulated in rice grain, potentially affecting health. Methylmercury in rice field surface water can bioaccumulate in wildlife. We evaluated how introducing aerobic periods into an otherwise continuously flooded rice growing season affects MeHg dynamics. Conventional continuously flooded (CF) rice field water management was compared with alternate wetting and drying, where irrigation was stopped twice during the growing season, allowing soil to dry to 35% volumetric moisture content, at which point plots were reflooded (AWD‐35). Methylmercury studies began at harvest in Year 3 and throughout Year 4 of a 4‐yr replicated field experiment. Bulk soil, water, and plant samples were analyzed for MeHg and total Hg (THg), and iron (Fe) speciation was measured in soil samples. Rice grain yield over 4 yr did not differ between treatments. Soil chemistry responded quickly to AWD‐35 dry‐downs, showing significant oxidation of Fe(II) accompanied by a significant reduction of MeHg concentration (76% reduction at harvest) compared with CF. Surface water MeHg decreased by 68 and 39% in the growing and fallow seasons, respectively, suggesting that the effects of AWD‐35 management can last through to the fallow season. The AWD‐35 treatment reduced rice grain MeHg and THg by 60 and 32%, respectively. These results suggest that the more aerobic conditions caused by AWD‐35 limited the activity of Hg(II)‐methylating microbes and may be an effective way to reduce MeHg concentrations in rice ecosystems.
    Type of Medium: Online Resource
    ISSN: 0361-5995 , 1435-0661
    URL: Article
    DOI: 10.2136/sssaj2017.05.0158
    RVK:
    RA 4845
    Language: English
    Publisher: Wiley
    Publication Date: 2018
    detail.hit.zdb_id: 241415-6
    detail.hit.zdb_id: 2239747-4
    detail.hit.zdb_id: 196788-5
    detail.hit.zdb_id: 1481691-X
    SSG: 13
    SSG: 21
    Library Location Call Number Volume/Issue/Year Availability
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    Online Resource
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