Spodic Horizons Research Articles

Lithological discontinuities in Podzols developed from sandstone cover beds in the Stolowe Mountains (Poland)

Podzols developed within so-called cover beds were examined on a slope built of Cretaceous sandstones in SW-Poland. Their typical feature is an easily recognizable stratification of regolith, evidenced in the dichotomy of soil texture and dense subsoil. Heterogeneity of soil profiles is manifested in vertically differentiated sequence: (1) dense, skeletal and massive layer, comprising usually Bs and BC horizons, sometimes Bhs/Bh horizons with strong platy structure is overlain by (2) the uppermost, relatively young layer, consisting of loose sandy material, bearing single coarse fragments of a less weathered sandstone, hosting AE, E and partially Bh horizons. This remarkable layering of slope sediments caused a distinctive lithological discontinuity at the boundary of E and B horizons, evidenced by the differences in: (i) rock fragments' content, (ii) degree of rock clast weathering, (iii) distribution of highly resistant minerals, and (iv) fluctuation of silt and sand fractions within profiles. Lithological discontinuity influences both the lateral podzolization, and the thickness and depth of albic and spodic horizons along the slope catena. Regarding the temporal order, the lowermost layer was influenced by periglacial conditions at before the Boreal; presumably as the surface layer (high score of pollen grains). The age of surficial sandy layer (based on pollen record) could be established at Subatlantic and correlated with forest cutting and intensive surface erosion (charcoal dating: 960+/−30calBP). Neither layers that originated from the eolian processes were distinguished nor any admixture of allochthonous material was found, therefore “typical” middle and upper periglacial cover-beds are not present in this sequence. In any case, Podzols that were formed from the slope sediments in the Stolowe Mountains are polygenetic and of the Holocene age.

Properties and classification of volcanic ash soils around Lake Kuwanuma on the eastern footslope of Mt. Funagata in Miyagi prefecture, northeastern Japan

One of the developments in recognition of soil properties and different soils is from morphological to analytical. With an incorporation of analytical data, transitional soils can be systematically named using a key-out order as well as typical soils. Our major objective was to evaluate soils with multiple forming processes such as andosolization, podzolization, etc., using soil analytical data, selecting a small area having different soil names based on soil morphological properties. According to a local soil map, Ando soils, Brown forest soils (Dark) and Wet and Dry podzols soils are adjacently distributed around Lake Kuwanuma on the eastern footslope of Mt. Funagata in Miyagi prefecture, northeastern Japan. We studied the morphological, chemical and mineralogical properties of these soils and classified them according to the recent Comprehensive Soil Classification System of Japan (CSCSJ), United States Department of Agriculture Soil Taxonomy (ST) and the World Reference Base for Soil Resources (WRB). The elevation of Lake Kuwanuma is 780 m above sea level and a plateau is located next to a steep slope on the western side of the lake. Three pedons were sampled from the northern side of Lake Kuwanuma, and 3 additional pedons were sampled from the plateau. The average difference in elevation between these two groups of pedons was 229 m. All 6 pedons were classified as Andosols in CSCSJ, Udands in ST and Andosols in WRB. Thus, andosolization was the dominant soil-forming process throughout the study area. The major modification of Andisols in the study area was caused by forest vegetation. Of the 6 pedons sampled, three were classified as Fulvudands in ST and had the Fulvic prefix qualifier in WRB. Furthermore, weak podzolization was suggested on the basis of soil profile observations. One pedon on the plateau had a Bs horizon, which satisfied the spodic horizon requirements of ST. Thus, weak podzolization, especially on the plateau, was another accessory characteristic in the present study area. The nearby distribution of Podzols soils and Ando soils in the local soil map may be explained by differences in temperature, leaching intensity and other factors. A podzolic subgroup of Andosols/Udands was desired to express the properties of pedons on the plateau in the lower categories of the recent soil classification systems.

Measurement and modeling of phosphorous transport in shallow groundwater environments

Leaching of phosphorus (P) from agricultural soils, especially those that are sandy, is adversely impacting P-limited ecosystems like Florida's Everglades. A more developed understanding of P and water management strategies and their effects on P leaching is needed to achieve reductions in subsurface P losses, especially from intensively managed dual cropping systems under plastic mulch in shallow water regions. We compared the effects of conservation P and water management strategies with traditional practices on P transport to groundwater. A 3-year experiment was conducted on hydrologically isolated plots with plastic-mulched successive cropping systems to compare high (HEI) and soil test based recommended (REI) external input (water and fertilizer P) systems with traditional sub-irrigation (seepage), and REI with a potential water conservation subsurface drip irrigation system (REI-SD) with regard to groundwater P concentrations above and below the low conductivity spodic horizon (Bh). The REI treatments had higher available storage for rainfall and P than HEI. Use of both REI systems (REI=2098μg/L and REI-SD=2048μg/L) reduced groundwater P concentrations above the Bh horizon by 33% compared to HEI (3090μg/L), and results were significant at the 0.05 level. Although the subsurface drip system saved water, it did not offer any groundwater quality (P) benefit. Mixing and dilution of influent P below the low conductivity Bh horizon between treatments and with the regional groundwater system resulted in no significant differences in groundwater P concentration below the Bh horizon. Groundwater P concentrations from this study were higher than reported elsewhere due to low soil P storage capacity (SPSC), high hydraulic conductivity of sandy soils, and a high water table beneath crop beds. The HEI system leached more P due to ferilizer P in excess of SPSC and used higher irrigation volumes compared with REI systems. Despite a 40% difference in the average amount of added fertilizer P between HEI (187kg P2O5/ha) and REI (124kg P2O5/ha), soil Mehlich 1 P (M1P) values were similar for both systems while they received Pinput. Soil M1P for REI and REI-SD increased to a maximum of 55mg/kg while they received Pinput, and then gradually decreased after Pinput ceased. However, M1P for HEI increased steadily to a maximum of 145mg/kg by the end of the study with continued Pinput. Mehlich-1 P measured six years after the study still showed relatively high levels of P, a legacy effect of Pinput. The main factors influencing groundwater P concentration varied by seasons. During fall with frequent rainfall, the concentrations were influenced mainly by M1P and Pinput, and highlight a need for greater focus on Pinput management (vs. water management) during this season. However, during the dry period of spring, a greater focus on irrigation management is required since depth to water table and rainfall also become contributing factors. Three multivariate models (r2=0.67 to 0.93), for spring, fall, and annual periods, were developed for predicting groundwater P concentrations for a wide range of water and P inputs (0 to 191kg P2O5/ha of Pinput). The uniqueness of these models is that they use readily available hydrologic (rainfall and water table depth), management (Pinput), and soil (M1P) data commonly monitored by growers when managing water and nutrient inputs on agricultural landscapes. The development of similar models may not be necessary for other agro-ecosystems in similar regions since long-term data collected in these regions may be applied, with verification, to the models presented here.

Metal and organic matter immobilization in temperate podzols: A high resolution study

Aluminium and Fe fractions were obtained in samples from two temperate podzols by selective extraction with NaOH (Aln, Fen), Na-dithionite-citrate (Ald, Fed), acid NH4-oxalate (Alo, Feo) and Na-pyrophosphate (Alp, Fep) following the traditional fractionation procedures, and also by the use of the chlorides of K (AlK), La (AlLa) and Cu (AlCu) as non-buffered extractants for Al. Carbon content was also determined in the Na-pyrophosphate extract (Cp). Soil sampling was done at high-resolution to allow a more detailed characterization of the vertical processes than the traditional sampling by whole soil horizons. Results showed that Alp and Fep make a large proportion of the Alo and Feo meaning that organoaluminic complexes dominated in the “active” metal pool instead of inorganic compounds. The degree of metal saturation of soil organic matter (estimated by the (Alp Fep)/Cp molar ratios) increases with depth, especially in the uppermost samples of spodic horizons (Bhs1) where it increases up to 0.1. Aluminium dominates in the adsorption positions of the organic matter in the spodic horizon (Fep/Alp ratios <0.5), except in the Bhs1 horizon (ratios >1), indicating that the immobilization of Fe containing complexes occurs 10–15cm above that of Al. The highly stable Al–OM complexes accounted on average for 60% of the organoaluminic associations (>70% in the Bhs horizons). The moderately stable complexes predominate in A horizons (57–77% in ACB1 and 37–48% in ACB2) and the largest proportions of low stability complexes were found in the uppermost samples of the spodic horizons (Bhs1) of both soils (9–21%), together with the highest Fep contents and a decrease in pH values. From a stepwise multiple regression model it is suggested that pH is the main variable accounting for the stability of Al–OM compounds together with C and organically bound Fe contents. It is suggested that the illuviation of unsaturated organic acids lower the pH in upper spodic horizons, leading to the complexation of metals from formerly precipitated organometallic complexes and/or leading to their redissolution, enabling their migration to deeper soil layers. Iron complexes would be less soluble at soil pH, resulting in a differentiation of an upper Fe-rich Bhs1 horizon and a lower Bhs2 Al-rich horizon. The depth variation in C accumulation was found to be related to the proportion of highly stable Al–OM fraction.

Vegetation influence on soil formation rate in a proglacial chronosequence (Lys Glacier, NW Italian Alps)

Climate change has huge impacts on alpine ecosystems. One of the most visible effects in the Alps is glacier retreat since the end of the Little Ice Age (LIA), which caused the exposure of previously glaciated surfaces. These surfaces are open-air laboratories, verifying theories regarding ecosystem and soil development.In order to increase our knowledge on the effects of time and vegetation primary succession on soil development in proglacial areas, we sampled soils and surveyed plant communities on stable points in the proglacial area of the Lys glacier, in the Italian north-western Alps (Valle d'Aosta Region). The sampling points were located on dated sites (based on literature and/or historical photographs).Glacial till is attacked by weathering processes immediately after deposition and stabilization, with a consequent loss of soluble compounds, decrease of pH and primary mineral weathering. The speed of these processes was largely increased after the establishment of a continuous vegetation cover, thanks to the organic matter accumulation caused by litter input and root decomposition below the soil surface.On sialic glacial tills, below timberline and under a quasi-climax larch–Rhododendron forest, fast and steady decrease in pH values, increase in organic matter content and horizon differentiation were observed. In particular, genetic eluvial horizons formed in approximately 60years, while diagnostic albic horizons were developed after ca. 90years, pointing to an early start of the podzolization processes. Cheluviations of Fe and, secondarily, Al were analytically verified. However, illuviations of Fe, Al and organic matter in incipient B horizons were not sufficient to obtain diagnostic spodic horizons on LIA materials.Under grazed grassland below timberline and alpine prairie above timberline, acidification and weathering were slightly slower, and no redistribution with the depths of Fe and Al oxi-hydroxides was observed. A cambic Bw horizon developed on the oldest LIA moraines.Therefore it seemed that this fast onset of the podzolization process in comparison to other proglacial chronosequences in the Alps was mainly driven by vegetation properties rather than by specific climatic conditions.

Aspects of soil phenolic matter (SPM): An explorative investigation in agricultural, agroforestry, and wood ecosystems

This paper assesses the distribution of soil phenolic matter (SPM) in soil environments from a pedological perspective, with particular emphasis on soil horizonation and its involvement in pedogenic processes.The study was conducted on 15 soil profiles (Andosols, Calcisols, Cambisols, Lixisols, Phaeozems, Podzols, Umbrisols) covering five distinct ecosystems. Although the ecosystems were virtually homogeneous in and of themselves, they represented strongly contrasting climates, geolithology and morphology, land use and vegetation cover (intensive agriculture, chestnut grove, alpine pasture, woody reforestations, and natural woods). Three main SPM fractions were categorised: (i) “total” (SPMt), (ii) “soluble” and/or “labile” (SPMs), and (iii) the fraction with a “high” (SPMh) affinity for the soil body.The SPMh and SPMs contents varied significantly, averaging 2.84±0.52gkg−1 and 0.07±0.02gkg−1, respectively. Thus, these fractions appear to belong to different soil organic matter (SOM) pools. Indeed, the SPMs fraction was characterised by transitional, ephemeral low-weight molecules, which continuously reached the soil through both plant metabolism/decay and SOM degradation and were subsequently transformed into larger materials (humic matter, organo-mineral complexes) and/or lost by leaching and mineralisation. The SPMh fraction is likely involved in pedogenic processes that are primarily driven by the transport/translocation of colloidal phases under the following conditions: (i) in the early stages of horizon differentiation or, more specifically, in transport processes from the overlying A horizons and (ii) in cheluviation phenomena leading to the formation of spodic horizons. Moreover, SPMh also appears to be involved in early “in situ” alteration of cambic horizons. This involvement may result from the strong etching/complexing activity of soluble polyphenols from the overlying horizon, which promotes “in situ” weathering of the parent material.The total amount of SPM in a given environment greatly depended on the environmental conditions, which ranged from 0.02gkg−1 in an intensively cultivated Haplic Cambisol to 13.14gkg−1 in an Andic Cambisol under natural downy oak cover. Additionally, the SPMh/SPMs and SPMt/SOM% ratios decreased significantly from natural woods to intensive agriculture systems and may therefore indicate the extent of different anthropic impacts, such as soil cover/land use, in different ecosystems.

Pedogenic processes of placic and spodic horizons in subtropical subalpine forest soils with contrasting textures

Placic (Bsm) and spodic (Bhs) horizons are common in subalpine or alpine forest soils in Taiwan. Bsm horizons are found more usually in finer textured soils than those with Bhs horizons. To understand the different formation processes in Bsm and Bhs horizons in a humid subtropical ecosystem, we identified micro-morphological features by using scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and electron probe micro-analysis (EPMA), and determined the physiochemical properties by chemical extractions and clay mineralogy. The study included four pedons with well-developed Bsm horizons from our previous study and four with well-developed Bhs horizons at other sites. Both sites were in subtropical mountain forests with similar climate, topography and general geology but over regoliths with distinctly different textures. Micro-morphology revealed a vughy (small cavities lined with in-washed materials) microstructure in Bsm horizons but a granular structure with bridge microstructures between coarse grains in Bhs horizons. Chemical analysis revealed more free pedogenic iron (Fed) and aluminium (Ald) in Bsm than in Bhs horizons, but more organically complexed Al (Alp) in Bhs horizons. Energy dispersive spectrometry revealed predominant Fe, oxygen (O) and carbon (C) in the matrix of the Bsm horizons, whereas Al, silicon (Si) and C were the major elements of interstitial materials in Bhs horizons. Polarizing microscopy and EPMA spectra confirmed the illuvial nature of organic Al complexes in Bhs horizons. The transformation of clay minerals showed more intense podzolization in Bhs horizons than in Bsm horizons. The different formation mechanisms in Bsm and Bhs horizons result from contrasting texture; redox processes are predominant in Bsm horizons because of the clayey texture whereas podzolization is predominant in sandy Bhs horizons.

The evidence of lateral podzolization in sandy soils of Northern Poland

Abstract Evidence of slope-scale element translocation (lateral podzolization) has been documented in sandy areas of Northern Poland. Accumulative soils enriched with organic matter, iron, aluminum, and manganese (Entic Podzols) have been found at the bottom of closed, small depressions in inland-dune fields and undulated surfaces of glaciofluvial terraces. Together with the surrounding weakly or moderately developed podzolic soils (Albic Arenosols, Haplic Podzols) Entic Podzols form regular toposequences, and seem to be geochemically linked. In the light of chemical, micromorphological and SEM-EDS analyses, the whole solum of the soils under study exhibit diagnostic features of the illuvial spodic horizon; however, they do not have an eluvial albic horizon. Landscape position and features of the studied soils suggest inter-pedon translocation of organic matter, iron and aluminum as the concept of Entic Podzol genesis. Furthermore, high values of Fe d /Fe t and Fe o /Fe d ratios in their solum can be interpreted as evidence of allochtonous character of iron accumulation. The results of this study show that the lateral podzolization process can be common even along slopes built from loose, permeable sandy deposits, where one would not expect any effective intra-layer solution flow. Organic matter and compounds illuviated to the Bhs horizon are the probable factors limiting percolation and modifying the direction of solutions movement. On slopes of more complex morphology, small closed depressions act as geochemical traps, where compounds leached from the upper slope soils can accumulate. Radiocarbon dating carried out on a buried Entic Podzol found in one of the profiles shows that the process has continued for more than 1200 years.

Influence of afforestation on soil genesis, morphology and properties in glacial till deposits

A study of soil morphological, physical and chemical properties was performed in woodland of different ages, in which spruce (Picea abies), aspen (Populus tremula) and birch (Betula pendula) growing stocks have colonized former agricultural land. The aim of the study was to clarify changes in soil genesis, morphology and properties due to the afforestation of abandoned agricultural land in glacial till deposits. The research showed that soil in these deposits (loamy sand, loam, clay) retains the morphological properties of agricultural land for up to 100 years. Secondary podzolization features in the soil profiles were observed within 100 years of the start of afforestation, whereas the diagnostic properties of Albic and Spodic horizons had not developed in the soil profile after 200 years. This study demonstrated that the morphological and physico-chemical properties of forest litter horizons, including the accumulation of organic substances, are dependent on forest age; however, changes in the properties of mineral soil horizons are mainly related to woodland age. Following the afforestation of agricultural lands, changes in soil pHKCl, organic matter content and extractable Al and Fe concentrations occur more rapidly than changes in soil diagnostic properties and profile formation.

Profiles in History

2012 Members of the Professional Soil Classifiers Association of Alabama (PSCAA) convened on the Gulf Coast in Baldwin County for their 37th annual meeting and field tour in June 2012. The field tour was developed by USDA-NRCS District Conservationist and PSCAA President Joey Koptis along with members Greg Brannon and Jerome Langlinais, USDA-NRCS soil scientists, and Frank Cochran, USDA-NRCS soil conservationist. One of the field tour stops was to a pitcher plant bog where small spade holes were excavated and Joey Koptis led discussions on hydric soil indicators and the formation of a spodic horizon in one of the pedons. (left to right) Sanderson Page, Joey Koptis, and Jerome Langlinais examining hydric soil indicators. Other stops on the field tour included backhoe pits in a Malbis soil and a soil similar to the Robertsdale series. Discussions at these sites focused on plinthite, fragic properties and soil drainage. PSCAA Members Examine Hydric Soil Indicators The Professional Soil Classifiers Association of Alabama was organized by a small group of soil scientists in 1975 to promote the profession of soil classification and to further the increase and dissemination of information concerning all aspects of soil science. For more information on PSCAA, visit their website at www.alabamasoilclassifiers.org. Photo and information courtesy of PSCAA. 2011 In 2011, field work in the 48 contiguous states of the United States was completed for the Rapid Assessment of U.S. Soil Carbon (RaCA), a project initiated by the USDA-NRCS Soil Science Division in 2010. The project was a huge undertaking that involved the collection of 144,833 samples that were collected from the upper one meter of 32,084 soil profiles at 6,017 randomly selected locations. National Resources Inventory (NRI) sites were used as the basis for random selection of sample sites stratified by soil group and land use/land cover. At each location soil morphology and landscape characteristics were described, and limited vegetation and management information was collected. The collection and analysis of the many samples involved more than 300 soil scientists working in the National Cooperative Soil Survey Program, including 24 universities across the nation. A Toast to the Completion of RaCA Fieldwork Pictured above are Bev Harben and Phil Smith, USDA-NRCS soil scientists, “toasting” with bulk density sampling cores while celebrating the completion of their final sampling site in Solano County, California. Source: USDA-NRCS Soil Science Division, http://soils.usda.gov/survey/raca/. Photo courtesy of MLRA Soil Survey Office 2-TEM, Templeton, CA. 2004 Careers that span 60 years are a rarity, and Terry Cook is that rare soil scientist who has worked in the field from 1953 through 2013. In 1953, he was one of three crew members selected from Cal Poly, San Luis Obispo by a National Park Service Ranger to work on severely eroding Ellis Meadow at an elevation of 2,792 meters. This meadow in Kings Canyon National Park was beginning to rapidly erode as a result of past grazing practices. In 1955, he was the crew chief who selected his own crew from the Cal Poly Soils Department. Erosion control measures, all installed by hand, included basket dams, posts and anchors, chicken wire, branches and thatch, and even large logs on the eroding edge of the meadow, as shown in the photo, that were successfully placed to slow the water down and trap sediment. Terry Cook Stands on Log He Placed in 1955 Terry Cook has led a very diverse career and has provided superb leadership in soil science for many individuals and groups. From 1955 to 1983, Terry Cook worked for the Soil Conservation Service (SCS) in California as a Soil Survey Party Leader, Area Soil Specialist, and State and Regional Correlator. From 1983 through 1990, he worked as an International Training Specialist for USDA Soil Conservation Service with Soil Management Support Services (SMSS). This work took him to many different countries where he conducted workshops, meetings, and training forums. He has been a soil consultant in Davis, CA since he retired from SCS in 1990. He has been an active participant and field trip organizer in many soil-related organizations. Photo and information courtesy of Kerry Arroues, retired USDA-NRCS Soil Scientist, Hanford, CA.

Profile distribution and temporal changes of sulphate and nitrate contents and related soil properties under beech and spruce forests

The behaviour of principal inorganic anions in forest soils, originating mainly from acid deposition, strongly influences the forest ecosystem response on acidification. The aim of this study was to describe seasonal and temporal changes of sulphate and nitrate contents and related soil properties under beech and spruce forests in a region heavily impacted by acidification. The Jizera Mountains area (Czech Republic) was chosen as such a representative mountainous soil ecosystem. Soil samples were collected at monthly intervals from April to October during the years 2008–2010 under both beech and spruce stands. Soil samples were collected from surface fermentation (F) and humified (H) organic horizons, humic (A) organo-mineral horizons and subsurface mineral (B) horizons (cambic or spodic). A deionised water extract was applied to unsieved fresh samples and the content of anions in these extracts was determined by ion chromatography (IC).In the studied soil profiles, the lowest amount of SO42− was found in the organo-mineral A horizons under both types of vegetation. Under spruce the highest amount of SO42− was determined in mineral spodic (B) horizons, where a strong sorption influence of Fe and Al oxy-hydroxides is expected. Under beech the highest amount was observed in the surface organic F horizons (forest floor). The amount of NO3− is highest in the F horizons and decreases with increasing soil profile depth under both types of vegetation. A significantly higher amount of NO3− was determined in soils under the beech stand compared to spruce. For both soil environments – under beech and also spruce stands – we have determined a general increase of water-extractable SO42− and NO3− during the whole monitoring period. The behaviour of SO42− and NO3− in the soils is strongly related to the dynamics of soil organic matter and particularly to the DOC.

Micromorfologia de horizontes espódicos nas restingas do Estado de São Paulo

Os solos de restinga são pouco estudados e conhecidos no Brasil. Neste trabalho, a micromorfologia de horizontes espódicos foi investigada em quatro locais do litoral do Estado de São Paulo (Bertioga, Ilha de Cananeia, Ilha do Cardoso e Ilha Comprida). A técnica possibilitou caracterizar as diferentes formas da matéria orgânica, e, juntamente com a descrição morfológica de oito perfis de solos representativos das restingas do Estado de São Paulo, objetivou-se discutir os mecanismos envolvidos na gênese dos horizontes espódicos desses ambientes. Entre os resultados alcançados, destaca-se: a presença de revestimentos orgânicos monomórficos na superfície dos constituintes grossos da maioria dos horizontes analisados, bem como o preenchimento quase completo da porosidade entre grãos de alguns horizontes cimentados e brandos, são evidências de que a clássica teoria da mobilização, transporte e precipitação de complexos organometálicos é válida para os solos estudados. No entanto, matéria orgânica polimórfica e, ou, resíduos vegetais em diferentes estádios de decomposição foram as principais pedofeições observadas em horizontes espódicos mal drenados e sotopostos a horizontes hísticos. Nesses, a decomposição pela mesofauna e microbiológica das raízes in situ é um importante mecanismo de acumulação de matéria orgânica em profundidade e formação dos horizontes espódicos. A atuação das raízes na formação desses horizontes, no entanto, vai além da sua decomposição: a fábrica e as feições da matéria orgânica de um horizonte cimentado, incluindo remanescentes radiculares, indicaram que as raízes podem atuar na imobilização da matéria orgânica por meio de seu mecanismo de absorção seletiva. Nesse processo, a solução do solo rica em carbono orgânico dissolvido é absorvida seletivamente pelas raízes, segregando parte do carbono complexado em sua superfície e no entorno destas, absorvendo água e nutrientes. A atuação continuada desse processo leva à precipitação da matéria orgânica iluviada e segregada por meio de sua desidratação, que é condicionada pela própria absorção radicular.

Factors related to Bh-horizon depth for artificial and natural E–Bh sequences

Aquods occur extensively in the coastal plain of the SE USA, where podzolization is mainly restricted to fluctuating water table conditions. Depths to upper boundaries of Spodic (Bh) horizons vary from a few cm to ≥75cm even under similar drainage conditions. Hence, seasonal water table depth parameters do not explain the wide variation in boundary depth. One objective of this study was to experimentally test the following hypotheses: (H1) Depth to the E–Bh boundary relates inversely to concentration of metal oxides, silt, and clay content of initial (“parent”) material for similar hydrologic conditions and organic acid activity; (H2) depth to that boundary is greater under higher organic activity for a given soil material and hydrologic condition. Another objective was to statistically evaluate how the composition of >270 natural Spodic horizons collected during the Florida Cooperative Soil Survey Program related to upper boundary depth. Thirteen sandy coastal plain soil materials of varying noncrystalline-metal-oxide- (Al and Fe), silt-, and clay contents were packed in columns and subjected to daily cycles of fluctuating water tables and dilute organic acid applications. Artificial E–Bh boundaries of variable depths were generated in the columns. Boundaries tended to be abrupt but topographically irregular. Clay- and extractable-noncrystalline Al and Fe contents were inversely related to final depth of artificial Bh horizons for the same water-table conditions. Higher oxalic acid concentrations produced deeper boundaries in the same materials; hence, local biogeochemical factors related to organic acid production are also likely to influence the ultimate Aquod morphology on the landscape. Silt-, clay-, and metal-oxide contents were significantly higher in shallower than in deeper natural Florida Spodic horizons.

Characterizing soils via portable x-ray fluorescence spectrometer: 2. Spodic and Albic horizons

Differentiation of horizons in soils formed in volcanic ash can be problematic as recent ash deposits often have the same morphological appearance as eluvial albic horizons. Furthermore, differentiation of spodic horizons can be difficult as multiple horizons can appear homogeneous. A portable x-ray fluorescence (PXRF) spectrometer was utilized to scan volcanic ash-derived Spodosols, Andisols, and Inceptisols in northern Idaho and southern Alaska. Distinct patterns of elemental concentrations were identified in soil profiles. These data can be used to quantitatively differentiate seemingly nondescript horizons. Organic carbon variability within soil profiles was found to significantly correlate to elemental concentrations as evidenced by strong regression r2 and low root mean squared errors (RMSEs). Specifically, Fe/Zr ratios proved useful for documenting spodic horizons in the studied profiles, and showed some potential for differentiating volcanic ash from true E horizons. In areas of frequent saturation or inundation, the PXRF also demonstrated the ability to distinguish depleted soil matrix materials from reduced Fe. Summarily, the PXRF proved to be a useful instrument for rapid, on-site analysis of volcanic ash soils.

Upbuilding pedogenesis under active loess deposition in a super-humid, temperate climate — quantification of deposition rates, soil chemistry and pedogenic thresholds

Although the importance of dust deposition as an integral component of terrestrial biogeochemical cycles is well-recognised, few studies have directly addressed pedogenic processes associated with dust deposition on the land surface itself, and if so, mainly as relict features. This work addresses this gap by looking at the pedogenic response to an active loess flux gradient in a super-humid, strong weathering environment on the west coast of New Zealand's South Island. Along the gradient, seven soil pits were examined for a range of soil physical (colour, texture, bulk density, structure, roots) and chemical properties (pH, Feo, Fed, Alo, soil organic carbon) measured to a depth of 50cm to capture the transitional changes arising from minimal to maximal loess deposition rates. Maximal deposition rate was estimated to be 28.4gm−2 y−1.Along the gradient towards the highest deposition rate, loess-free, sandy Spodosols changed to increasingly more finely-textured soils, ultimately featuring a two-fold increase of silt. The pedogenic oxides Feo, Fed and Alo gradually increased each by 50% and soil organic carbon by 60%. These increases were facilitated by continuous accession of loess. The loess mixed with organic matter at the surface and became increasingly weathered and leached with the time that it had spent undergoing eluviation. Subsequently, the loess increments were buried within the subsoil as part of an upwardly thickening spodic horizon (upbuilding pedogenesis). Because of the high deposition rates under maximum loess flux, Spodosol formation became ultimately retarded and an Inceptisol formed because loess supply overwhelmed topsoil leaching. Having also an illuvial subsoil horizon, this Inceptisol showed the strongest chemical indicators for podzolisation of the gradient. Soil data from supplementary sites suggested that more developed soils required lower loess fluxes to retard further pedogenic differentiation than younger soils.The existence of a loess gradient that is capable of forming distinctive deposits in a super-humid environment gives evidence that not only dry/arid climates (e.g. during glacials) are potentially suitable for the formation of aeolian substrates (loess). The study indicates enhanced soil organic carbon storage in soils as a result of loess deposition and concomitant pedogenesis.

Effects of four depths of spodic horizon on root morphology and nutrient partitioning of kenaf grown on sandy beach ridge soil

Kenaf has a potential to be an industrial crop in Malaysia. Hence, this study was conducted to investigate the root morphology, nutrient partitioning and yield of kenaf at various depths of spodic horizons in beach ridges interspersed with swales (BRIS) soil. Study was conducted at RhuTapai Research Station, Terengganu, Peninsular Malaysia. Kenaf was grown at L1 20 cm, L2 48 cm, L3 77 cm and L4 118 cm depth of spodic horizons. Texture was sandy with more than 90% sand. Soil pH ranged from 5.17 to 5.27, TC content ranged from 0.10 to 0.39% and TN content ranged from 0.01 to 0.03% at surface of the sandy soils at four locations with different depths of spodic horizons. Stem of kenaf was found higher in carbon and nitrogen content while bark was found in higher content of phosphorus grown at 20 cm depth of spodic horizon as compared to other depths of spodic horizons. No visual deformation was observed in roots of kenaf; generally kenaf root growth was stunted with the increase in depth of spodic horizons. Yield of kenaf decreased from 12, 19 and 21% at 48, 77 and 118 cm depths of spodic horizons as compared to 20 cm depth of spodic horizon, respectively. It is concluded that spodic horizon at 20 cm depth was not a problem for kenaf cultivation on sandy beach ridges soils. Key words: Kenaf root morphology, nutrient content, yield, depth of spodic horizon, sandy beach ridges soils.

Vertical distribution and soil organic matter composition in a montane cloud forest, Oaxaca, Mexico

In montane cloud forests (MCF), the main soil organic carbon (SOC) pool is believed to be constituted by organic debris accumulated on soil surface and, to a lesser extent, by the organic fraction associated with the mineral matrix. The vertical distribution of SOC within soil has strong implications on the composition, stabilization and turnover of the soil organic matter (SOM). In ecosystems like MCF, where the climatic and edaphic conditions varied with altitude, the SOM accumulation and stabilization mechanisms possibly respond to these changes. For that reason, we studied the vertical distribution, accumulation and chemical composition of SOM in five montane cloud forest communities located between 1,500 and 2,500 m a.s.l. Two main SOC accumulation patterns were found: one at 1,500, 1,950 and 2,400 m a.s.l., with SOC content gradually decreasing with depth (cumulative); and another at 2,050 and 2,500 m a.s.l. where SOC had a strong maximum in the surface horizon and a less pronounced increase the spodic horizon (eluviation–illuviation pattern). The total SOC pool in soil decreased in inverse relation to altitude from 227 C ha−1 at 1,500 m a.s.l. down to 143 mg C ha−1 at 2,500 m a.s.l. About 40–60 % of total SOC content corresponded to the surficial organic horizon. The chemical fractionation of the SOM denoted in general predominance of the fulvic acid fraction, and high content of humin and humic acid fractions. We considered that the main SOC vertical distribution processes were related to the raw humus accumulation, decomposition in situ, podzolization in the eluviation–illuviation pattern soils mainly.

Characterization and classification of soils in the Taquari river basin - Pantanal region, state of Mato Grosso do Sul, Brazil

Among the soils in the Mato Grosso do Sul, stand out in the Pantanal biome, the Spodosols. Despite being recorded in considerable extensions, few studies aiming to characterize and classify these soils were performed. The purpose of this study was to characterize and classify soils in three areas of two physiographic types in the Taquari river basin: bay and flooded fields. Two trenches were opened in the bay area (P1 and P2) and two in the flooded field (P3 and P4). The third area (saline) with high sodium levels was sampled for further studies. In the soils in both areas the sand fraction was predominant and the texture from sand to sandy loam, with the main constituent quartz. In the bay area, the soil organic carbon in the surface layer (P1) was (OC) &gt; 80 g kg-1, being diagnosed as Histic epipedon. In the other profiles the surface horizons had low OC levels which, associated with other properties, classified them as Ochric epipedons. In the soils of the bay area (P1 and P2), the pH ranged from 5.0 to 7.5, associated with dominance of Ca2+ and Mg2+, with base saturation above 50 % in some horizons. In the flooded fields (P3 and P4) the soil pH ranged from 4.9 to 5.9, H+ contents were high in the surface horizons (0.8-10.5 cmol c kg-1 ), Ca2+ and Mg² contents ranged from 0.4 to 0.8 cmol c kg-1 and base saturation was &lt; 50 %. In the soils of the bay area (P1 and P2) iron was accumulated (extracted by dithionite - Fed) and OC in the spodic horizon; in the P3 and P4 soils only Fed was accumulated (in the subsurface layers). According to the criteria adopted by the Brazilian System of Soil Classification (SiBCS) at the subgroup level, the soils were classified as: P1: Organic Hydromorphic Ferrohumiluvic Spodosol. P2: Typical Orthic Ferrohumiluvic Spodosol. P3: Typical Hydromorphic Ferroluvic Spodosol. P4: Arenic Orthic Ferroluvic Spodosol.

Potential for Plants to Remove Phosphorus from the Spodic Horizon

Under what conditions can plants be used to remove phosphorus from common Florida soils? This 5-page fact sheet shows how calculations for the phosphorus saturation ratio and soil phosphorus storage capacity at various soil depths can be used to determine whether to use phytoremediation as a strategy to remove phosphorus from the soil. Written by D. Chakraborty, V.D. Nair, W.G. Harris, and R.D. Rhue, and published by the UF Department of Soil and Water Science, October 2011. SL359/SS560: The Potential for Plants to Remove Phosphorus from the Spodic Horizon (ufl.edu)

Fluctuating water table effect on phosphorus release and availability from a Florida Spodosol

Spodosols in Florida exhibit a unique hydrology including a fluctuating water table that can often reach the surface horizon during the summer months. This paper evaluated the effects of fluctuating water table on P fluxes and availability in a typical Florida Spodosol. The study was conducted on an established bahiagrass (Paspalum notatum Flugge) pasture grown on a Smyrna sand (sandy, siliceous, hyperthermic Aeric Alaquods). Phosphorus fluxes were measured using suction cup lysimeters installed at depths of 15, 30, 60, 90, and 150 cm. The 15- and 30-cm deep lysimeters were located above the spodic (Bh) horizon, whereas the remaining lysimeters (60-, 90- and 150-cm) were below the Bh horizon. A pressure transducer was installed at the center of the experimental site to monitor changes in water table depth. Two anion exchange membranes (2 × 6 cm) were buried in each plot at a 15-cm depth to estimate in situ P availability. During the 2-year study, leachate P concentrations in the lysimeters above the Bh horizon increased as water tables rose in the months of August and September. Conversely, P concentration measured in the lysimeters below the Bh horizon remained relatively constant (0.02 mg L−1). Soil P availability also increased (from 3.2 μg cm−2 in June to 9.2 μg cm−2 in August) in response to rising water table. Results showed that the fluctuating water table conditions experienced during the summer months in Florida cause upward flux of P from the Bh horizon, which increased soil P availability and susceptibility to off-site transport.