Roles of iron and clay in Genesis of acid soils under a humid,temperate climate

The occurence of acid brown soils, podzols and podzolic soils, and the intermediate types of ochreous brown and brown podzolic soils over arenaceous granite in Vosges was closely correlated with the contents of iron rather than with calcium plus magnesium in the parent materials. Acid brown soils were associated with high and podzols and podzolic soils with low contents of iron, the limiting value being near 5 percent. Additional investigations in beech forests of soils derived from a variety of acid rocks indicated that contents of iron and clay in the parent materials controlled the type of humification of litter. With higher contents of iron and clay, humification gave rise to mull. With lower contents, mor or moder was formed. The nature of humification was believed responsible for tilting pedogenesis toward brunification or toward podzolization. In brunification, the clay-iron-humus complexes that are formed tend to be immobile and promote formation of crumbly structure. The “active iron” occurs as films around clay particles and thus links them to humus. In podzolization, on the other hand, the complexes formed are of humus with iron or aluminum but without clay. These are mobile and are translocated downward in profiles to form spodic horizons. The organo-metal complexes in ochreous brown and brown podzolic soils are mobile to only a limited extent. The combined results of these investigations demonstrate that contents of iron and clay rather than calcium in parent materials determine the pathway of pedogenesis from acid rocks under humid, temperate climates.     

Contribution of different proton sources to pedogenetic soil acidification in forested ecosystems in Japan

The contribution of different proton sources to pedogenetic soil acidification was evaluated for three Japanese forest soils, i.e. ando soil, podzolic soil and brown forest soil in relation to the respective soil forming processes. Soil acidification rate and net proton generation were quantified based on the theory of proton budget for the respective soil horizon compartments (mainly the O, A and B horizons) by measuring fluxes of solutes entering and leaving the soil horizon compartment and vegetation uptake. Protons were produced by the dissociation of organic acids and nitrification in the O horizon and then consumed by adsorption and decomposition of organic acids and nitrate uptake by vegetation in deeper soil horizons at all plots. Excess uptake of cation over anion by vegetation was highest among proton sources in the whole soil compartment at all plots. Pedogenetic soil acidification was considered to include cation leaching from surface soil horizons due to proton generation by the dissociation of organic acids and nitrification and subsequent cation excess accumulation in wood in the growth stage of forests. In ando soil, andosolization resulted from the low contribution of net proton generation by the dissociation of organic acids as well as a lower soil acidification rate and complete acid neutralization. Dissolved organic carbon (DOC) fluxes in ando soil were lower than those in podzolic soil and brown forest soil due to high adsorption capacity of amorphous materials. In podzolic soil, podzolization resulted from intensive acidification in the O horizon, which derived from net proton generation by the dissociation of organic acids and nitrification as well as cation excess uptake by vegetation due to concentrated fine root biomass in the O horizon, and subsequent high proton efflux to subsoil. The high fluxes of DOC and Al leached from surface soil horizons were considered to contribute to eluviation of Al from surface soil and illuviation in subsoil in podzolic soil. In brown forest soil, brunification resulted from a lower DOC flux from the O horizon due to high decomposition and adsorption by oxides, where podzolization was weakened by high acid neutralization. Thus, the three representative processes involved in the pedogenesis of Japanese forest soils were well characterized by quantification of the respective proton-generating and consuming processes in each soil horizon.     

Chemical and mineralogical properties of sandy and loamy-sandy ochreous brown earths in relation to incipient podzolization in a brown earth—podzol evolutive sequence

Chemical and mineralogical properties of ochreous brown earths have been studied with particular reference to: (1) the distribution within the profiles of Fe and Al compounds; (2) the occurrence of smectite-like clay minerals in surface horizons. Ochreous brown earths studied belong to a developmental sequence of forest soils, from acid brown earths to ferric podzols, developed on sandy or loamy-sandy acid parent materials. In such a soil sequence, both selective chemical and mineralogical data show clearly that podzolization is already active in ochreous brown earths, whereas such an incipient podzolization is quite undetectable by direct morphological observations. The distribution patterns of amorphous Fe and Al hydrous oxides and organic associations, clearly show the intergrade character of ochreous brown earths, when compared with the vertical distribution of Fe and Al forms in acid brown earths and podzolized soils. The Fe/Al ratio of both an NH₄-oxalate extract and an NaOH/Na-tetraborate extract buffered at pH 9.7, measured in the A₁B diagnostic horizon of ochreous brown earths, is a particularly appropriate and useful genetic criterion for the detection of incipient podzolization. Moreover, the presence of expansible clay minerals (degradation smectites) in the clay-sized fraction of the surface horizons of ochreous brown earths (A₁ and A₁B) can be considered as supplementary evidence of incipient podzolization.     

The properties, genesis and significance of a man-made iron pan podzol near Castletownbere, Ireland

Beneath a layer of artificially deposited peat debris, an eluvial E horizon and thin iron pan (Bsm) has developed in the upper part of the A_p horizon of a brown podzolic soil (Haplorthod) near Castletownbere, Ireland. The thickness of the E horizon and the depth of the pan are directly related to the thickness of the layer of peat debris. The original soil (Haplorthod) was strongly podzolized with a significant accumulation of organic carbon, iron and aluminium in the spodic Bs. The iron pan of the upper sequum, on the other hand, is rich in iron. This iron pan seems to have developed as a result of reduction of iron in the E horizon, transport of divalent Fe²⁺ cations and precipitation in the Bsm as Fe₂(OH)₃, after the peat layer was deposited. We conclude that podzolization and iron pan development were fundamentally different processes. The study suggests a fundamental change in the iron pan-blanket peat development sequence previously postulated by palaeoenvironmentalists in Ireland.     

The distribution of PG (green fraction of P type humic acid) and the degree of humification of PB (brown fraction of P type humic acid) in soils of central Japan

Abstract

Pg contents of soils chosen from the major soil groups occurring in the mountain area of Central Japan were measured by the method presented by the author in a previous paper. The Pg contents of the soils ranged from 0 to 0.58 per cent of the dry soils. In podzolic soils, Pg contents were high in A horizons and gradually decreased with depth and in some cases of brown forest soils, Pg contents were highest in B horizons. The percentage of Pg in humic acid ranged from 0 to 8.6 per cent, and the highest value was observed in the C horizon of Dando Bo soil, Pg contents were high in humid and acidic soils containing much humic acid. Humidity, soil pH and humus content may affect the Pg accumulation by controlling the activity of Pg-producing fungi. ? log K values of Pb were calculated to estimate the degree of humification of P type humic acids and indicated that Pb's were relatively immature.     

Identification of podzols and podzolised soils in New Zealand by relative absorbance of oxalate extracts of A and B horizons

A method for separating podzols and podzolised soils from other New Zealand soils is proposed. The method is based on measurement of the optical density of acid oxalate extracts of soils. A number of soil leaching sequences and some individual soils are examined.It is assumed that the optical density of the oxalate extracts is due mainly to extracted fulvic acid and that detection of appreciable quantities of this material in the B horizon indicates that podzolisation is an active process in the soil.The technique separated the soils of the leaching sequences well, following the observable increase of podzolic characteristics with increased leaching.When the B horizon/A horizon ODOE (optical density of the oxalate extracts) ratios were compared with the criteria for the spodic horizon in “Soil Taxonomy” (Soil Survey Staff, 1975), it was found that all soils with a ratio of less than 1.0 did not satisfy spodic horizon criteria and were not classified as podzol/podzolised. All the soils examined with ratios > 1.0 satisfied spodic horizon criteria or were classified as podzol/podzolised, usually both.     

Fixation of radiocaesium in an acid brown forest soil

The OAh and Ah horizons of acid brown and podzolic forest soils are reported to fix more radiocaesium than the mineral B horizons beneath them. We determined the respective influence of organic matter and clay minerals on the magnitude of Cs⁺ retention in a strongly acid brown forest soil in Belgium. The soil contained mica throughout the profile. Vermiculite was identified in the OAh and Ah horizons, and hydroxy interlayered vermiculite (HIV) in the Bw horizon. The OAh and Ah clay fraction retained much more Cs⁺ than the Bw horizon. The extraction of Al interlayers by Na-citrate resulted in a marked increase in Cs⁺ fixation in the Bw clays as well as the collapse of the vermiculitic layers after K⁺ saturation. Organic matter had a strong but indirect effect on Cs⁺ fixation. In the Bw horizon, acid weathering of layer silicates releases free Al and produces HIV minerals in which Al polymers block the access of radiocaesium onto Cs⁺-specific sites. In OAh and Ah horizons, free Al is complexed by organic acids. Consequently, the interlayer specific sites remain accessible for Cs⁺ fixation.     

Podzol formation in sandy soils of Finland

Podzolization occurs quickly in acidic parent materials with addition of acidic litter from coniferous trees. This study was conducted to evaluate Podzol formation and estimate lengths of time required to meet morphological and chemical criteria of podzolic B horizon and spodic horizon in Finland. Soil color, organic C, ODOE, and extractable Al and Fe were measured in a seven-pedon chronosequence (230–1800 years) and four older pedons (8300–11,300 years). The bulk mineralogical composition of the BC and C horizons was uniform with quartz, plagioclase and K-feldspar as main components and amphibole, illite and chlorite as minor components. The fine (<5 μm) fraction of selected samples was primarily amorphous allophone-like material with some mixed-layered illite–vermiculite. All pedons in the study met the criteria for albic horizons according to the FAO–Unesco, World Reference Base (WRB) and Soil Taxonomy systems. According to the FAO–Unesco system, all pedons had spodic B horizons and were classified as Podzols. According to the WRB system, none of pedons of the chronosequence had spodic horizons, whereas the older pedons met the criteria for a spodic horizon. About 4780 years were required to form a spodic horizon according to the WRB system. The oldest pedon of the chronosequence and the older pedons had spodic horizons according to Soil Taxonomy, but the younger pedons failed to meet the spodic horizon criteria. About 1520 years were required to form a spodic horizon that met the color and organic C criteria of Soil Taxonomy, whereas it took about 4780 years to meet the required accumulation of Fe and Al. This study points out the discrepancy between the color criteria and the criteria reflecting the accumulation of Al, Fe and organic matter in the B horizon.     

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.     

The soils of a typical slope in the Himalayas (Nepal): Their main characteristics and distribution

This study is based on a sequence of soils on a typical slope of the Himalayas in central Nepal from 2300 m to 4000 m. Above 2300 m the land is forested and at 4000 m forest gives way to alpine meadows.The soils have developed in silty loam materials derived from weathering of micaschists. They are humic, acid and strongly desaturated. Their spatial distribution is related to the bioclimatic zonation: acid brown soils and deep humic acid soils occur in the mountain zone and podzols and brown podzolic soils in the subalpine and alpine ones.Biological activity and “maturation” of humus decrease with increasing elevation. The podzolization process dominates. There is intense weathering of ferruginous phyllosilicates in eluvial horizons and accumulation of amorphous products in B horizons.     

Incipient podzolization processes in Humic Acrisols of southern Spain

Soils with morphological evidence of podzolization occur in Sierra Morena (southern Spain). Six soils, identified as Humic Acrisols, were sampled for detailed study. Distribution of oxalate- and EDTA-extractable Al in Fe in the profiles indicated that substantial amounts of both elements had been translocated from the A to the incipient podzolic B horizons. Part of the Al, but almost no Fe, was present as organic complexes, suggesting that these two elements were transported to, or remobilized in the B horizons by different mechanisms. Allophane was present, albeit in small amounts, in two soils. Both inorganic and organic theories of podzolization were able to explain the Fe and Al distribution data.     

Podzolization as a deferralitization process: a study of an Acrisol–Podzol sequence derived from Palaeozoic sandstones in the northern upper Amazon Basin

Morphological, geochemical and mineralogical studies were carried out in a representative soil catena of the low‐elevation plateaux of the upper Amazon Basin to interpret the steps and mechanisms involved in the podzolization of low‐activity clay soils. The soils are derived from Palaeozoic sandstones. They consist of Hydromorphic Podzols under tree savannah in the depressions of the plateaux and predominantly of Acrisols covered by evergreen forest elsewhere. Incipient podzolization in the uppermost Acrisols is related to the formation of organic‐rich A and Bhs horizons slightly depleted in fine‐size particles by both mechanical particle transfer and weathering. Weathering of secondary minerals by organic acids and formation of organo‐metallic complexes act simultaneously over short distances. Their vertical transfer is limited. Selective dissolution of aluminous goethite, then gibbsite and finally kaolinite favour the preferential cheluviation of first Fe and secondly Al. The relatively small amount of organo‐metallic complexes produced is related to the quartzitic parent materials, and the predominance of Al over Fe in the spodic horizons is due to the importance of gibbsite in these low‐activity clay soils. Morphologically well‐expressed podzols occur in strongly iron‐depleted topsoils of the depression. Mechanical transfer and weathering of gibbsite and kaolinite by organic acids is enhanced and leads to residual accumulation of sands. Organo‐metallic complexes are translocated in strongly permeable sandy horizons and impregnate at depth the macro‐voids of embedded soil and saprolite materials to form the spodic Bs and 2BCs horizons. Mechanical transfer of black particulate organic compounds devoid of metals has occurred later within the sandy horizons of the podzols. Their vertical transfer has formed well‐differentiated A and Bh horizons. Their lateral removal by groundwater favours the development of an albic E horizon. In an open and waterlogged environment, the general trend is therefore towards the removal of all the metals that have initially accumulated as a response to the ferralitization process and have temporarily been sequestrated in organic complexes in previous stages of soil podzolization.     

Podzolization and clay migration in spodosols of eastern France

Field observations and laboratory analyses of podzols developed on sandy Triassic parent material in the Vosges have demonstrated clay accumulation in the upper parts of spodic horizons, especially in the B_h horizons. To see whether clay accumulation corresponds to real clay illuviation, two types of podzol profiles have been studied. The first is an iron podzol, called “podzol forestier”, because it has been entirely developed under climax forest environment. The second, an iron-humus podzol, called “podzol de dégradation”, was first developed under forest and more recently (the last 1000 to 2000 years) under heath vegetation. Methods used in the study of the two profiles were the “isoquartz” alteration balance, clay mineral identification by X-ray analyses and micromorphholigical examination.For the podzol forestier, the data strongly support a hypothesis of illuviation of very fine micaceous clays (vermiculite), especially the ferriargillans in the B_h horizon. Consequently, it is believed that illuviation of the greatest part of clays promoted differentiation of podzol horizons. Podzolization is strongly redistributive.In the podzol de dégradation, the identified clay minerals are the same as in the podzol forestier but the pedological features in the B_h horizon correspond to those of classic spodic horizons (mixed concentration and grain coatings). Moreover, podzolization is geochemically strongly subtractive in this second type of podzol.Inasmuch as the podzols de dégradation are developed from the podzols forestiers, the authors define an evolutionary time-sequence: the first phase of forest soil genesis is regulated by the double process of clay illuviation and redistributive podzolization. The following degradation phase connected to the particular nature of heath vegetation and to abundant chelating organic compounds induces the disruption of the ferriargillans previously formed in the B_h horizon, the formation of an agglomeroplasmic fabric microstructure and above all, the elimination of hydrolyzed products of minerals from the profile. During this last phase, a strongly subtractive podzolization prevails over clay illuviation.     

Sodium hydroxide-tetraborate in comparison with sodium pyrophosphate as an extractant of “complexes” characteristic of spodic horizons

Sodium hydroxide-tetraborate at pH 9.7 was found not to be a suitable extractant of the amorphous substances characteristic of podzolic B horizons as defined in Canada. Similarly, it does not appear to be a useful basis of a criterion for differentiating spodic horizons as defined in the United States. Hydroxide-tetraborate extracted very little Al and Fe from about half of the podzolic B horizons tested. Compared with pyrophosphate, it extracted from 2 to 50% as much Fe and from 10 to 70% as much Al. Furthermore, hydroxide-tetraborate extracted only small proportions of the Fe and Al from synthetic Fe- and Al-fulvic acid products tested.Evidence regarding the relative specificaties for organic-complexed Al and Fe of hydroxide-tetraborate and sodium pyrophosphate is considered. Deductions about the genesis of podzolic soils based upon experiments with hydroxide-tetraborate are discussed in relation to other evidence.     

新疆阿尔泰山西北部山区针叶林下土壤的形成特征

本文研究了新疆阿尔泰山西北部山区针叶林下土壤的形成特征，并与我国东部地区的灰化土，暗棕壤进行对比，认为林下土壤与灰化土，暗棕壤有明显的差异，冷凉湿润的水热状况和发育的季节性冻层对于土壤的形成具有重要作用，宜将林下土壤定名为寒棕壤。     

Aluminum compounds in soil solutions and their migration in podzolic soils on two-layered deposits

The fractional composition of aluminum compounds was studied in soil solutions obtained using vacuum lysimeters from loamy podzolic soils on two-layered deposits. The concentration of aluminum was estimated in brooks and a river draining the area with a predominance of these soils. In soil solutions, the concentration of aluminum was experimentally determined in the following compounds: (1) organic and inorganic monomers, (2) stable complexes with HAs and FAs together with polymers, and (3) the most stable complexes with HAs and FAs together with fine-crystalline and colloidal compounds. The total Al concentration in soil solutions from forest litter was 0.111–0.175 mmol/l and decreased with depth to 0.05 mmol/l and lower in solutions from the IIBD horizons. More than 90% of the Al in the solutions was bound into complexes with organic ligands. Some amount of Al in solution could occur in aluminosilicate sols. The translocation of Al complexes from the litter through the AE horizon to the podzolic horizon was accompanied by an increase in the ratio between the Al concentration in fraction 2 and the C concentration in the solution. The concentrations of Al_tot in the surface waters varied in the range from 0.015 to 0.030 mmol/l. Most of the Al came to the surface waters from the litter and AE horizons and partially from the podzolic horizon due to the lateral runoff along the waterproof IIBD horizon. Approximate calculations showed that the recent annual removal of Al from the AE and E horizons with the lateral runoff was 7 to 560 mg (3–21 mmol) from 1 m².     

Podzol development with time in sandy beach deposits in southern Norway

The coastal areas of SE Norway provide suitable conditions for studying soil development with time, because unweathered land surfaces have continuously been raised above sea level by glacio‐isostatic uplift since the termination of the last ice age. We investigated Podzol development in a chronosequence of six soils on sandy beach deposits with ages ranging from 2,300 to 9,650 y at the W coast of the Oslofjord. The climate in this area is rather mild with a mean annual temperature of 6°C and an annual precipitation of 975 mm (Sandefjord). The youngest soil showed no evidence of podzolization, while slight lightening of the A horizon of the second soil (3,800 years) indicated initial leaching of organic matter (OM). In the 4,300 y–old soil also Fe and humus accumulation in the B horizon were perceptible, but only the 6,600 y–old and older soils exhibited spodic horizons. Accumulation of OM in the A horizons reached a steady state in <2,300 y, while in the B horizons OM accumulated at increasing rates. pH dropped from 6.6 (H₂O)/5.9 (KCl) in the recent beach sand to 4.5 (H₂O)/3.8 (KCl) within approx. 4,500 y (pH_H2O)/2,500 y (pH_KCl) and stayed constant thereafter, which was attributed to sesquioxide buffering. Base saturation showed an exponential decrease with time. Progressive weathering was reflected by increasing Fe_d and Al_d contents, and proceeding podzolization by increasing amounts of pyrophophate‐ and oxalate‐soluble Fe and Al with soil age. These increases could be best described for most Fe and Al fractions by exponential models. Only the increasing amounts of Fe_p could be better described by a power function and those of Fe_o by a linear model.     

Soil formation as affected by pit and mound microrelief in Massachusetts,USA

The influence of pit and mound microrelief on soil formation was investigated by detailed observations of a cross-section through a pit and mound in a hemlock (Tsuga canadensis) forest in western Massachusetts, in the northeastern United States.Soil forming processes during the last 140 years have led to taxonomically different soils due to this microrelief. Part of the annual precipitation apparently does not infiltrate into the mound but moves laterally through organic surface layers into the pits. This resulted in more intensified translocation of Fe, Al and organic matter in the pit profile. The ensuing soil met the spodic horizon criteria as defined in Soil Taxonomy and was classified as a Lithic Haplorthod. Neighboring, undisturbed soils had pronounced E, Bhs, and Bs horizons, the latter qualifying as spodic horizons on the basis of chemical criteria. These soils, however, did not meet the minimum depth requirement of 12.5 cm for spodic horizons and therefore, were classified as Typic Dystrochrepts. The soil developed in the mound showed less horizon development and was classified as a Typic Dystrochrept.Taxonomic changes resulting from the pit and mound microrelief affected less than 6% of the area and appeared not to have a significant impact on the purity of map delineations.     

Occurrence and properties of soils on sandy beach ridges in the Kelantan–Terengganu Plains,Peninsular Malaysia

A study was conducted along the Kelantan–Terengganu Coastal Plains, Peninsular Malaysia to explain the occurrence of sandy beach ridges and to determine the physico-chemical properties of the soils formed on them. Two or occasionally three series of sandy ridges running parallel to the shoreline occur in the area. These ridges are believed to have been formed by the continuous action of the sea waves following changes in the sea level during the Holocene, the oldest ridge being the one farthest away from the shoreline. In between these ridges occurs a slight depression, usually occupied by soils under submerged condition. The soils on the ridges are subjected to the processes of soil formation, mainly podzolization. There is no horizon differentiation in the soils on the ridge nearest to the shoreline. However, soils on the older ridges contain spodic horizon, occurring at varying depths. Drainage and the depth below which this spodic horizon occurs are the deciding factors for determining soil type (series). Physically, the soils are sandy containing > 95% sand, with the drainage varying from moderately well to excessively-drained for the soils on the ridges. Under this condition, the mineralogy of the clay and silt fractions is dominated by quartz; some feldspars, mica, kaolinite, gibbsite and anatase are also present. Sandy nature of the soils on beach ridges, extreme leaching, low cation exchange capacity and low exchangeable bases leads to their low productivity.     

Evaluation of dwell as a nitrification inhibitor and its interaction with nitrogen source and soil properties

Abstract

A method is described in which boron is extracted from ignited soils with 0.05M mannitol and 0.01M calcium chloride. This method extracts similar amounts of boron to the commonly used hot‐water soluble method. Both methods are equally well related to the development of boron deficiency and with boron taken up by Pinus radiata D. Don seedlings grown in pot trials but the mannitol method is better suited to routine analyses. Increased mannitol‐extractable boron in surface soils was related to increased growth and less boron deficiency symptom development by P. radiata grown on yellow podzolic but not on yellow and red earth soils. In the yellow podzolic soils there was little extractable boron below the A1 horizon. In contrast the distribution of boron in the profile of earth soils was more uniform and thus the analysis of surface soils did not reflect the total amount of available boron.