A1 Horizon Research Articles

In Situ Study of Podzolization on Tephra and Bedrock

AbstractA study was initiated in the Washington Cascades to examine processes of soil genesis in situ through the analysis of soil solution chemistry. Suction plate lysimeters were used to continuously extract soil solution held below 0.1 atm from the O2, A2, IIB2hir, and IVB32 horizons of a forest soil. Movement of elements was in the order Si > Al > Fe > Mn. The O2 and A2 were the source of the Fe, Al, and Si which entered the IIB2hir. Most of the Mn originated in the A2. Virtually all of the Fe, 48.5% of the Al, 50% of the Mn, and 15% of the Si which left the A2 remained in the IIB2hir. According to the soil's morphology, it appears to be a Spodosol, and the lysimeter data indicates that podzolization is the major process of soil formation. The soil does not meet the criteria of a Spodosol in Soil Taxonomy. Two explanations for this are: (i) the soil has not become a Spodosol yet because the intensity of weathering is low or (ii) soil taxonomy criteria for the Spodosol order are not broad enough and need to be broadened to include soils of this type.

SIZE FRACTIONATION, DISSOLUTION ANALYSIS, AND INFRA‐RED SPECTROSCOPY OF HUMUS COMPLEXES IN ANDO SOILS

SummaryEight samples of Ando soil A1 and buried A1 horizons of different ages were fractionated into clay‐, silt‐, and sand‐size separates, and the yields and carbon contents of these separates were determined. The clay‐size separates were subjected to two series of successive extractions, 1) 0.1 M Na4 P2 O7/2% Na2 CO3/0.5 M NaOH and 2) dithionite‐citrate/2% Na2 CO3/0.5 M NaOH; and to difference infra‐red spectroscopy for identification of the extracted constituents.The result indicated that humus evolves from forms with a very low complexing ability for Al and Fe into forms that complex Al and Fe in the A1 horizon, and that humus further interacts with allophane‐like constituents, allophane and imogolite in the buried A1 horizon. These reactions between humus and inorganic constituents result in formation of silt‐ and sand‐size aggregates which are stable to sonic wave treatment, but are broken down into finer particles upon boiling with H2 O2.

CHARACTERISTICS OF THE MINERAL CONSTITUENTS OF SOME ALBIC AND SPODIC HORIZONS AS RELATED TO THEIR CHARGE PROPERTIES

Some physical, chemical and mineralogical properties of five albic and six spodic horizons were studied in an attempt to relate their composition to their charge properties. The samples investigated contained less than 3% clay and had specific surface areas less than 30 m2/g. pH values measured in M NaF were lower than 9.5 for the A2 horizons but higher than 10.5 for all the Bir horizons studied. Mineralogy of the clay fraction was studied by using X-ray diffraction, infrared spectroscopy, and thermogravimetric analysis along with selective chemical dissolution analyses. Chloritized vermiculite was the dominant phyllosilicate in the Bir samples, while montmorillonite dominated in the clay fraction of most of the A2 samples. Amorphous constituents, as determined by acid ammonium oxalate and 0.5 N NaOH extractions, represented up to 40% of the clay-sized fraction of some of the samples. Primary minerals such as quartz, feldspars and to a lesser extent hornblende and magnetite were the major constituents of the coarser fractions. The change in chemical and mineralogical compositions of the A2 and Bir horizons sharply reflected the variation that existed in their overall electrochemical behavior as shown by the potentiometric titration curves. A2 horizons usually behaved like a constant surface charge system, while the Bir samples reacted like a constant surface potential system with PZC values varying between pH 4.1 and 4.9.

The widening of valley incisions by soil fall in a forested Keuper area, Luxembourg

AbstractIn the gently undulating Keuper region of Luxembourg valley incisions in mixed oak‐beech forests are being widened by a process of soil fall. This process is optimized by a number of ecological conditions. Soil profiles examined in the Deifebaach catchment, located between Larochette and Ettelbruck, generally have an abrupt boundary between the silty surface soil (A2 horizon) and the dense clayey subsoil (B horizon). This boundary is marked by the formation of a dense root mat. The subsoil contains a large proportion of oriented clay and is subject to swelling and also to dispersion. Clay particles translocated downwards increase the density of the subsoil and decrease its permeability. The soils are very poorly drained, being waterlogged for much of the year, and have experienced some fragipan development.When the subsoil is exposed it disintegrates into an incoherent mass of aggregates and recedes beneath the root mat which supports the overlying material until it eventually collapses. The nature and amount of soil fall recession is examined along a 320 m reach of die Deifebaach. It was found that at least 30 per cent of the right bank and 40 per cent of the left bank are subject to recession by soil fall.

Soil Deterioration on Campsites: Northern Forest Types

AbstractCamping use and soil deterioration were monitored on 12 campsites in northern Michigan during their third and fourth camping seasons. Sites were on previously undisturbed Gogebic fine sandy loam (Typic Fragiorthod), under mature northern forest cover. Percentage of litter cover, soil macropore space and depth to A2 horizon decreased, and soil bulk density increased with time during both use seasons. Deterioration increased greatly on all campsites with intensity of use. Except for depth to A2 horizon, measured parameters recovered partially over winter, but recovery was less than deterioration during the previous summer.

Experimental and simulated transport of phosphorus through sandy soils

Reversible equilibrium adsorption‐desorption relationships were inadequate for describing the transport of orthophosphate through water‐saturated and water‐unsaturated cores from surface A1 and subsurface A2 horizons of Oldsmar fine sand. Using a kinetic model with nonlinear reversible adsorption‐desorption improved descriptions of phosphorus transport through these soils. Phosphorus effluent concentrations were described best by using an irreversible sink for chemical immobilization or precipitation with a nonlinear reversible kinetic adsorption‐desorption equation.

Influence of environmental factors on the growth of the beech

The measurement of growth indices of the beech (Fagus sylvativa) and of environmental conditions at 59 random sampling points were made in two areas of woodland in the Gutland region of Luxemburg (Grengewald and Warschent). Statistical analysis revealed that the main factor responsible for the growth of the beech is the parent material. Beech trees on sandstone are growing significantly better than those on marl. Moreover on sandstone, the beech trees are lowest on places having a thin A1 horizon and/or a high humus content of the A1 horizon and/or a southwest exposure.

Soil classification and survey studies at Ginninderra

Studies were made of the interrelations of soil properties, their spatial variation, and the relations between sampling sites at Ginninderra Experiment Station near Canberra. Soil morphology was recorded at 0-10 cm, 15-25 cm (usually A2 horizon), 41-51 cm (usually B horizon) and 66-76 cm, and general profile features were noted. Samples from the 0-10 cm and 41-51 cm were analysed chemically, and bulk density and water held at 0.1 bar determined on 0-7.5 cm cores. Simple correlations between morphological and other properties of the topsoil were almost all negligible. Correlations in the B horizon were somewhat stronger, though few correlation coefficients exceeded 0.5 in absolute value. Ordination by principal coordinate analysis showed sample sites to be evenly spread in a single roughly spherical cluster in the three main dimensions of property space. Four classifications, two systematic, one a map, and the fourth a numerical classification, were unable to predict values of soil properties sufficiently well to be useful; the properties must be measured where they are of interest by a purpose-designed sampling scheme. Soluble potassium varies little between points 5 m apart, but very considerably over distances 56-180 m. Two-thirds of the variation in soil phosphorus at Ginninderra occur within 5 m and the remainder at more than 180 m. Variation in pH increases fairly steadily up to 56 m, and the rest at more than 180 m. Most variation in bulk density and water content occurs within 18 m, though the total variation is small. Variation in morphology occurs mainly within 5 m and at more than 180 m. Reasonable maps can be made of phosphorus and morphology by pooling data from samples from 5 m diameter circles, or by bulking samples from them, spaced on a grid of approximately 200 m mesh. For potassium a grid mesh of no more than 56 m is needed to map the variation, though pooling data from 5 m circles would give a small improvement.

Palaeoenvironmental Interpretation of a Buried Soil at Achnacree, Argyll

The relationships between a humus iron podsol buried beneath a field bank at Achnacree, Argyll, western Scotland, and a normal sub-peat profile on an adjacent site are considered. It is suggested that the coarse-textured parent material and Ericaceous vegetational characteristics of the site induced and promoted progressive degradation of the profiles, which was possibly aided and enhanced by primitive cultivation practices. Translocation of humus is much more marked under the normal profile which reflects the operation of a more intensive pedogenic process which may be related, in turn, to the temporal factor in soil formation. Parallels are drawn with a site at Loughaveema, Co. Antrim, and it is suggested that soil deterioration was partially responsible for bog growth during the Sub-Boreal and Sub-Atlantic. THE Moss of Achnacree lies some 8 km north-east of Oban and covers about 312 ha of the southern part of the Benderloch peninsula at the entry to Loch Etive. The Moss, lying at an altitude of 65 m covers an extensive fluvio-glacial deposit derived mainly from Ben Cruachan granites and Loch Lorn schists. The deposit is considered by McCann (1961) to mark a halt in the retreat of a valley glacier which occupied Loch Etive. Since the late eighteenth century the edge of the Moss has been cut back, partly for fuel and in part to increase the area of arable land available to crofts located on the perimeter of the Moss. In 1968, a bank or field wall was discovered at G.R. NM 921349 overlying an old land sur- face. Both the bank and the surface had subsequently been buried by the growth of the Moss. Thus the bank and the surface beneath the bank clearly antedate parts of the peat which has built up to a depth of about 1-5 m. The bank is visible for some 60 m behind Croft 3 at Black Crofts, North Connell, before it disappears under the present peat face; it is about I-8 m wide and 0-4 m high and consists of two parallel lines of rounded granite and flatter schist stones with a central infill of rounded and sub-angular stones up to 8 mm in diameter within a gravelly loam matrix. This infill was thrown in from shallow ditches cut just outside the bank walls. About 5 cm from the surface of the infill bleached sand grains occur, showing the weak development of an A2 (Eb) horizon.

Effects of zinc-smelter emissions on forest soil microflora.

Within 2 km of a zinc (Zn) smelter in Palmerton, Pennsylvania, near the Lehigh Water Gap, up to 13.5% Zn by weight has been measured in the O2 horizon of the soil, and up to 8% Zn in the A1 horizon. The total numbers of bacteria, actinomycetes, and fungi (measured by dilution plate counts) were greatly reduced in the most severely Zn-contaminated soils compared with control soils. The reduction of microbial populations may be a partial cause of the decreased rate of litter decomposition at Lehigh Gap. Growth of most bacteria from control sites was reduced by 100 to 200 muM Zn, most actinomycetes by 100 muM Zn, and most fungi by 100 to 1000 muM Zn in thin-Pablum extract agar (TPab). All the tested actinomycetes and non-spore-forming bacteria isolated from Zn-contaminated Lehigh Gap soils were Zn-tolerant, growing normally in media containing 600-2000 muM Zn. Most fungi, regardless of source, were capable of at least 50% of normal growth at 700 muM Zn. Zinc-tolerant bacteria, actinomycetes, and fungi were readily isolated from low-Zn soils, suggesting that selection for Zn tolerance may proceed rapidly. Acidophilic Mortierella species have been selectively eliminated near the smelter, apparently because of elevated soil pH. Peryronellaea glomerata (Corda) Goidanich and Coniothyrium spp. were found only in the high-Zn soils.

Scanning Electron Microscopy of Cherts in Relation to the Oxygen Isotopic Variation of Soil Quartz

AbstractQuartz isolated from soils by the pyrosulfate-H2SiF6 method and chert samples of various origins were examined with the scanning electron microscope. Quartz isolates of the 20–50μm from the A2 and B21t horizons of the Baxter soil (AR), with quartz δ18O of 18·2 and 19·0‰, respectively, showed a mixture of detrital quartz particles and chert clusters of aggregates of fine euhedral quartz crystals. The 2–5 μm fractions of both horizons consisted mainly of euhedral quartz particles. The 20–50 μm fraction from the underlying chert, with a δ18O = 29·6‰, consisted of aggregates of euhedral quartz particles 1–10 μm dia and of subhedral particles 0·1–0·5 μm dia. In the soil fractions, the size and shape of the quartz particles as well as oxygen isotope data indicated that the aggregates were from the underlying chert but that irregular, unaggregated grains were detritally admixed loess, particularly in the medium and coarse silt fractions. This mixing of chert (of low temperature origin and heavy oxygen) with detrital quartz (of high temperature origin and light oxygen) gave rise to the intermediate δ18O values in the soil quartz. The SEM of cherts of different geological ages showed different morphologies. Prismatic, polyhedral microcrystalline quartz of 1–10 μm size as well as submicron, euhedral particles were observed in cavities. Submicron, subhedral particles and interlocking quartz grains were characteristic of Precambrian chert. Quartz grains more than 100 μm in size isolated by HCl from Ordovician dolomite (WI) had large (many microns) subhedral overgrowths and attached clusters of 0·1–0·5 μm microcrystalline quartz. A Danish flint formed in chalk had calcite-lined cavities (x-ray emission determined) in which spheroidal fibrous chalcedony occurred.

Classification des sols par une méthode multivariable. Application à une séquence bioclimatique méditerranéo-alpine sur roches-mères calcaires

The sequence extends from an elevation of 10 m to 2200 m. All told, 220 soil profiles were studied. These soil profiles were grouped in the French classification system.The morphology of the profiles permitted definition of eight “referencelrd horizons. For these horizons, 58 pedogenetic variables were defined from the results of physical and chemical analyses.For each profile the following environmental variables were defined: vegetation level, vegetation formation and lithological type of calcareous parent material.The pedogenetic difference between two profiles was measured by a taxonomic distance based on the presence or absence of the “reference” horizons and on the differences between common horizons. The distance between every pair of profiles are summarized by a phenogram with a fitness which commonly is higher than 80%. The groups of the phenogram are in turn summarized and discussed at five levels of synthesis, each grouping explained by the discriminant power of the pedogenetic variables and by the discriminant power of the environmental characteristics. Furthermore, the agreement between the numerical classification and the French classification is measured by the discriminant powers of French classification groups and subgroups.The first and second level of synthesis show three large groups: 1.(1) Soils that are very weakly developed. These soils are very shallow. In this subdivision fall all the rendzina soils, part of the humic carbonates soils (sols humiques carbonatés) and part of the litho-calcic humiferous soils (sols lithocalciques humifères) of the French classification.2.(2) The soils without a calcareous reserve. Three subdivisions are present: 2.1.(a) The soils of the first group are in complete agreement with the fersiallitic soils without calcareous reserves, formerly called Mediterranean red soils (sols fersiallitiques sans réserve calcique) in the French classification. Their exchange complex is slightly to moderately unsaturated, their pH is neutral and they all are leached.2.2.(b) The second subdivision also consists of leached soils, but these have an acid reaction and their exchange complex is mainly desaturated. This subdivision is made up podzolized; it includes the largest share of the modal leached soils (sols lessivés modaux) of the French classification. The other subgroup includes soils that are slightly leached but more podzolized.2.3.(c) The third subdivision consists also of acid soils with an exchange complex very desaturated but they are not leached. This subdivision coincides with the modal brown (sols bruns modaux) and the acid brown (sols bruns acides) soils of the French classification.3.(3) The soils with calcareous reserve. This group has three subdivisions: 3.1.(a) The first one is made up of very organic soils of the humid mountain Subalpine and Alpine vegetation levels. These soils are subdivided in two subgroups which differ in the nature of organic matter.3.2.(b) The organic matter content of the second subdivision is lower. All of these soils are saturated and have a neutral pH in the A1 horizon. They correspond mainly to calcic brown soils (sols bruns calciques) of the French classification. The two further subdivisions of this group are one including soils with a calcareous (B) horizon and another with a calcic (B) horizon.3.3.(c) The last great subdivision coincides with the fersiallitic soils with calcareous reserve (sols fersiallitiques à réserve calcique) of the French classification (formerly red Mediterranean soils) found on hard limestone under Mediterranean conditions. All these soils are saturated to slightly calcareous and have an A1 horizon with alkaline pH. They are subdivided into typical fersiallitic soils and fersiallitic soils with a BCa horizon.Leaching (lessivage) of clays and of sesquioxydes occurs under very different conditions, and four are identified. Moreover, the environmental conditions on which the fersiallitic soils are found are indicated.

Crop Response to Chiseling and Irrigation in Soils with a Compack A2 Horizon

Crop Response to Chiseling and Irrigation in Soils with a Compack A2 Horizon

Metsätyypin määräytyminen maalajin ja maaperän kemiallisten ominaisuuksien perusteella

This study consists of 1228 profiles taken from forest soils mainly situated in South and Central Finland. Nine per cent of the soils are located in the Oxalis-Myrtillus type (OMT), 56 percent in the Myrtillus type (MT), 28 percent in the Vaccinium type (VT), 5 per cent in the Calluna type (CT), and 2 per cent in the Cladina type (CIT). Four layers of each profile were analyzed. In the podsolized soils (80 per cent of all cases) the layers investigated were the litter layer (A0 horizon), the leaching layer (A2), the enrichment layer (B1—2), and the subsoil (C). In the clay, silt and sand soils, in which the podsolization was weak, the uppermost sample was taken from the litter horizon (A0), the second one down to 20 cm, the third from a depth of 20—40 cm., and the fourth at a depth of 40—60 cm. The types OMT, MT and VT are found in all soil types. There are no clay, silt or finer fines and samples taken from CT and CIT, while 57 per cent of all cases were in OMT. On the other hand, only 3 per cent of the sand samples came from OMT, while 54 per cent of the CT samples and 42 per cent of the CIT samples were sand. In general, the uppermost layers of forest soils are the most acid ones. The average pH-value of the litter layers in each forest type is about one pH-unit lower than that of the subsoil of the same type. The mean values of pH(H2O) in the litter layers decrease from pH 4.7 in OMT to pH 4.0 in CIT. According to this study, the litter layer is the richest layer in nutrients in forest soils. The differences between the mineral soil layers are small in each nutrient in the same forest type. The average exchangeable calcium and potassium contents in the surface soil increase with better forest types. The average Ca contents of the mineral soil layers in OMT vary from 366 to 1 060 mg/l soil while the corresponding numbers of CIT, CT and VT are 36-117mg/l. The litter layer of OMT has the highest potassium mean value (177 mg/l) while the lowest value (7 mg/l) is found in the subsoil of CIT. The content of readily soluble phosphorus in the humus layer is 4-10 times as high as that in the deeper mineral soil layers. This is the only regularity to be found in the P contents between the different forest and soil types. Dividing the samples into soil type groups, we can say that the higher the mean values of calcium, potassium and pH, the richer the forest type they represent. Carbon and nitrogen determinations were made from surface soil samples only. The C/N ratio decreases quite regularly from 42 (CIT) to 24 (OMT).

HYPOHALITE OXIDATION OF HUMIC ACIDS

Humic acids from the A1 horizon of a Chernozem black soil and from a weathered medium volatile bituminous coal were treated with a selective oxidant, namely sodium hypochlorite solution. Over 50 percent of the total carbon in both the humic acids appeared as CO2. Coal humic acid furnished predominantly benzene carboxylic acids, while the soil humic acid yielded a high proportion of aliphatic mono-, di-, and tricarboxylic acids. A good carbon balance indicates the complete oxidation of both the humic acids. Proceeding from the known chemistry of hypohalite oxidation, it is concluded that soil humic acids represent a special group of mixed alkyl-aryl-cycloalkyl compounds in which Sp2 carbon represents over 80 percent of the total carbon. If such humic acids are accepted as precursors of coal formation, the present study indicates that “maturation” converts the cyclo-alkyl skeletal arrangements of the component molecules from a normal bicyclo- or hydro-aromatic system to a bridged tricyclo- or more complex system at the expense of longer alkyl chains.

The Formation of 2:1–2:2 Intergrade Clays in some Norwegian Podzols

AbstractThe distribution of 2:1-2:2 intergrade clays has been investigated in some podzolized soils from Norway. In some of the profiles the intergrade clay mineral appears to be concentrated in the A2 horizon; in others, where smectite is predominant in the surface horizon, the maximum accumulation of the intergrade is observed in the B2 horizon. Smectite and vermiculite have been found to be the precursors of the intergrades of the A2 and B2 horizons respectively. A possible explanation to account for the observed variable pattern of occurrence of intergrades in soils is suggested.

Fungi from Canadian coniferous forest soils

The fungus flora from four pine forest soils was investigated. Qualitative studies used a soil-washing method, whereas quantitative investigations were performed using a direct observation technique. Results indicate that the fungus populations on litter and humus from all four forest soils are fairly similar, with Cladosporium herbarum, Aureobasidium pullulans, Alternaria sp., and various members of the order Sphaeropsidales being common in the litter, and Trichoderma and Penicillium species increasing in frequency in the F and H layers. The fungi isolated from the mineral soil horizons were more varied in nature, but certain genera seemed to be found frequently; these included Mortierella, Chrysosporium, Oidiodendron, Paecilomyces, Cylindrocarpon, Torulomyces, and sterile dark fungi.A detailed investigation of a Pinus strobus forest at St. Williams, Ontario, revealed no distinct seasonal patterns in the relative frequencies of the species of fungi.Quantitative studies showed that, in all soils, mycelial content decreased with depth from the humus. A comparison of the four sites showed a wide variation in fungal mycelium, varying from 30 m/g dry soil under Pinus strobus (in the A1 horizon) to 1540 m/g under P. contorta during May. Seasonal data from the P. strobus forest indicate a peak in mycelial content during August.

The relationship of respiration in organic and mineral soil layers to soil chemical properties

Respiration rates of the forest floor, exclusive of the L layer, and of the mineral horizons from three soils developed under pine and hardwoods in the North Carolina Piedmont were measured with a Warburg respirometer. Respiration, based on carbon content of the soil, decreased with depth through the A1 horizon, but subdivisions of the A2 showed no difference. When all soil layers were considered, there were no significant differences in respiration between cover type or soil series. However, in the least decomposed organic layer, the F1, respiration of pine litter was 77 per cent of that of hardwood litter, and respiration of Georgeville or Colfax soils was only 58 per cent of that of Iredell soil. Regression analyses, primarily with inorganic soil nutrient factors, accounted for over 90 per cent of the variation in respiration in the organic layers but for less than 50 per cent in the mineral soil under hardwoods. Up to 15 factors were included in equations, but four factors explained at least 70 per cent of the variation accounted for by regression.

Forest Windthrows and Their Influence on Soil Morphology

AbstractThe variability in thickness of the O and A2 horizons was studied on a sandy loam forest soil in the Great Lakes‐St. Lawrence Region of southern Ontario. Horizon thicknesses were recorded in 1.3 cm (0.5 inch) classes for each 10.2 cm (4 inches) of horizontal distance on the faces of each soilpit. Soilpits were located both subjectively on windthrows and randomly in the study area. Thickness frequency distributions for O horizons were normal and for the A2 horizons Poisson‐like. Both were independent of recent fire history and sampling method. It may be inferred that the disturbance by windthrow is infrequent in relation to O horizon formation, but frequent relative to A2 horizon development. Microtopographic position had a slight effect; thicknesses in top positions being somewhat less than for bottom positions. Horizon distortions related to windthrow disturbance were recorded for only 19% of the soil profiles sampled.

The Chemical Degradation of a Humic Acid

A humic acid (HA) extracted from the A1 horizon of a Brunizem soil was degraded in the unmethylated and methylated form by sequential reaction with oxidants of increasing strength. The HA was first oxidized with alkaline cupric oxide; the products were then further degraded by oxidation with first alkaline KMnO4 and then with H2O2 in alkaline solution. Unmethylated HA was also degraded by Na-amalgam reduction. The degradation products were extracted into organic solvents, methylated, and separated by preparative gas chromatography into relatively pure components which were analyzed by mass spectrometry and micro-i.r. spectrophotometry. A matching of the mass and i.r. spectra and gas chromatographic retention times of the isolated components with those of authentic specimens led to their identification.The experimental data show that the HA contains a relatively easily degradable portion, which comprises guaiacyl and syringyl units and which may be lignin-derived (about 10% of the total weight). This material is degraded by CuO–NaOH oxidation and Na-amalgam reduction. The bulk of the HA structure, however, consists of a more condensed, chemically complex "core", which degrades on more drastic oxidation into complex phenolic and benzenepolycarboxylic acids. It is likely that the "core" originates in part from condensed lignin and in part from products of microbial synthesis. Of the methods investigated, the CuO–NaOH and the KMnO4 oxidation of methylated HA appear most promising for providing information on the chemical structure of the HA.