A1 Horizon Research Articles

A Study of Extractable Soil Cobalt in Soils of the Southeastern United States

AbstractThe relationship between 2.5% acetic acid‐dithizone extractable soil cobalt and the amount of cobalt in black gum leaves, a cobalt indicator, was investigated for 71 widely distributed soils of the southeastern United States. The soil samples were from both good areas and areas where cobalt deficiency in ruminants would be expected on the basis of previous analyses. The extractable cobalt values appeared to separate the Ground‐Water Podzols, the Humic‐Gleys and the Low Humic‐Gleys from the better drained Regosols and Red‐Yellow Podzolic soils studied. At comparable cobalt concentrations in the black gum, the extracted cobalt was less from the imperfectly to poorly drained soils than from the well‐drained soils. For each of the two broad groups of soils, a significant correlation was obtained between extractable soil cobalt for the A1 horizon and the cobalt concentration in the black gum. Because of the variability in horizon thickness among the different soils, the cobalt values were calculated for the 0‐ to 6‐ and 0‐ to 12‐inch depths. The correlation between these values and plant cobalt was also good. The acetic acid‐dithizone extractable cobalt appears useful in indicating areas of potentially low soil cobalt in the Southeast where deficiency in cattle or sheep might be a problem.

Worm‐Worked Soils of Eastern South Dakota, Their Morphology and Classification

AbstractSoil survey field mapping of Brookings County, South Dakota, showed extensive areas of soils with nearly complete destruction of zonal profile horizonation as the result of mixing by intensive worm‐working. These worm‐worked profiles have moderately thick, black, recognizable A1 horizons, grading through completely mixed horizons of B2 with A1, A1 with B2, B3ca with B2, B2 with B3ca, or other combinations of horizons, before grading into the comparatively unmixed parent material. Laboratory analyses were made on some of these profiles in conjunction with the survey and with this study. Field studies were later extended, through the use of transects, to the surrounding areas of South Dakota. From these transect studies the area of occurrence of these soils was delineated. Worm‐worked soils were found in Wisconsin tills ranging from Iowan through Mankato in age and also in Wisconsin loess mantling the Iowan and Tazewell tills. These profiles resemble in some characteristics the “thick” or “fat” Chernozem of Europe. The name “Vermisol” is suggested to represent a more specific group classification for grassland soils displaying the unique profile characteristics associated with intensive worm‐working.

The availability of potassium in some Tasmanian soils. I. The variability of soil potassium in the field and its fractionation

The potassium status of Frodsley sandy loam and some associated soils from the Fingal district, north-eastern Tasmania, has been investigated. Regularly spaced sampling of surface soils on a rectilinear grid pattern disclosed a variability of exchangeable potassium values in the field much greater than recorded for soils elsewhere; even for 3-ft spacings there was a sevenfold range. The need for adequate sampling of experimental areas is stressed. The median value for exchangeable potassium in the A1 horizon of Frodsley sandy loam was 0.31 m-equiv./100 g for "developed" areas and 0.35 m-equiv./100 g for "undeveloped" areas. Values for the A2 horizon were closely correlated with those for the corresponding surface horizon, but only about one-third as high. The amounts in the B horizon tended to approximate to those in the A1 horizon except for soils with high values in the surface. The potassium-supplying capacity of the soils was assessed by fractionation of the potassium into water-soluble, exchangeable, difficultly exchangeable, hydrochloric acid-soluble, and total potassium. In Frodsley sandy loam approximately 35 per cent. of the exchangeable potassium appeared in the water-soluble form, which suggested that there may be moderate losses from this soil by leaching. Ten minutes' boiling with normal nitric acid released only about 90 per cent. more potassium than was present in the exchangeable fraction. Boiling normal nitric acid extracted much less potassium from some samples of this soil type than did cold normal ammonium chloride from others, because of the great variability of exchangeable potassium. Concentrated hydrochloric acid dissolved a further 0.60.7 m-equiv./100 g on the average. These low values for the two latter fractions are taken to indicate the poverty of this soil type in reserves of potassium and, with the relatively low values for the exchangeable fraction, explain the widespread responses to potassium reported in field experiments. Examination of the minerals of the clay fraction of Frodsley sandy loam supported the chemical data in regard to the poor potassium status of these soils. Separation of sand, silt, and clay from the B horizons of two profiles showed that much of the total potassium was present in the coarser fractions of the soil. Type A, a soil associated with Frodsley sandy loam on river terraces, had a similar potassium status. Soils formed on dolerite were significantly higher in all categories of potassium.

Some Notes on Clay Minerals in Podzol Profiles in Fennoscandia

Montmorillonite is found to be a predominant clay mineral in the < 2/z fraction of the A2 horizon of podzol profiles in Fennoscandia, even when these are only 300 years old. Irt fractions between 2/~ and 20/~ vermiculite and. hydrobiotite predominate, but are rarely detected in the fraction coarser than 20/z. Vermiculite and hydrobiotite are also found in the finer fractions of the B horizon, but are only rarely detected in the C horizon where their presence is apparently due to contamination with interglacial or older products of weathering. The presence of kaolinite in some profiles is explicable in the same way.

Freezing‐Point Depressions in Stabilized Soil Aggregates, Synthetic Soil, and Quartz Sand

AbstractThe freezing‐point method, using a small probe‐type thermistor as the sensing element, was used to study certain factors believed to lower the freezing‐point depression of soil moisture. The factors investigated were aggregate size, particle size, and undercooling temperature. The materials used were homogeneous and consisted of Palouse silt loam obtained from the A1 horizon, synthetic soil, and quartz sand.The Palouse silt loam was treated with soil conditioner, formed into aggregates, and separated into groups of various sizes. The freezing‐point depression measured on the various groups of aggregates increased with decreasing size of aggregates. This same trend was obtained for different‐sized sand separates. With successive freezing and thawing, the freezing‐point depression decreased for Palouse silt loam aggregates but was relatively unchanged for sand separates.The synthetic soil was made from ground quartz sand and illite clay. Part of the synthetic soil was treated with various rates of soil conditioner and formed into aggregates. The freezing‐point depression, made on aggregates of 1 to 2 mm. diameter, increased with increasing rate of soil conditioner.Different undercooling temperatures had little effect in changing the freezing‐point depression for Palouse silt loam or sands. However, the freezing‐point depression was increased with increasing undercooling temperatures for nonaggregated synthetic acid‐soil.

MORPHOLOGY AND GENESIS OF THE SOILS OF THE CARIBOU CATENA, IN NEW BRUNSWICK, CANADA

Soils of the Caribou catena occur in the rolling Uplands of the northeastern section of New Brunswick. The well drained soils in this region are members of the podzol great soil group.Four soil profiles, representing the catenary sequence, were selected for study. Investigation included both field and laboratory studies.Field studies indicated that profiles of all soils in the better drained positions had the same horizon sequence but the sola became thinner towards the base of a slope. The A2 horizon in the well drained position was replaced by an A1 in the imperfectly and poorly drained positions.The sola of all soils possessed high percolation rates and low bulk densities. Calculations indicated that, when compared to the C horizons, increases in silt and net losses in clay had taken place in all horizons of the well drained and imperfectly drained soils.The profiles showed marked gains in organic matter in the A0, A1 and B horizons.Aluminium had accumulated in the B horizons of all profiles. A small net gain in iron had occurred in the three best drained profiles. The associated Dark Grey Gleysolic soil had decreased in iron. The surface horizons showed the greatest concentration of exchangeable cations.

A Characterization of the Sebree‐Chilcott Soil Series Association (Slick Spots) in Idaho

AbstractA study was made of the Sebree‐Chilcott soil series association of southwestern Idaho with respect to morphology, physiography, and physical and chemical properties.Parent materials are of fluviatile and lacustrine origin occurring on terraces of different geologic age. The Sebree soil (slick spots) is relatively impermeable with little or no vegetation. Diameter of the spots vary from a few inches to 50 feet or more, with irregular shapes.The soils studied exhibit solodized characteristics with textural and color B horizons of solonetz morphology overlying prominent CaCO3 accumulations. Degree of cementation of the calcareous layers appears to be related to geologic age. The surface has a silt loam texture.Slick spot soils have a very thin A2 horizon overlying thicker B2 layers characterized by high exchangeable Na and in most cases high concentrations of soluble salts. Ions that predominate are Na+, SO42‐ and Cl‐. Gypsum is present in the lower B2 and B3 horizons. Horizons of prominent lime accumulation have a bowl‐shaped form under the slick spot. The data indicate that slick spots represent retarded soil‐forming processes which have somehow resisted the efforts of nature in their normal development.

Characteristics and Genesis of Low Humic Latosols

AbstractThe soils belonging to the great soil group of Low Humic Latosols have developed on basic crystalline rock materials in a semiarid to subhumid climate of subtropical and tropical regions having a pronounced dry period. The soil profiles of this group are characterized by the development of a weak A1 horizon in a solum which is predominantly kaolin clay. The solum is uniform in its chemical and mineral composition. The kaolin group make up &gt; 50% of the clay fraction, together with iron oxides and with small amounts of gibbsite.The silica/sesquioxide ratios of the clay fractions of the soils of the Low Humic Latosol group range from 1.1 to 1.7, with the majority of soils falling within the range of 1.30 to 1.55. The silica/alumina ratios range between 1.7 to 2.3, with an average of approximately 2.0.The physical properties of the soils of the Low Humic Latosol group are clays which have the physical properties characteristic of silty clay loams due to their high content of kaolin and iron oxide.

ALKALINE PERMANGANATE OXIDATION OF THE ORGANIC MATTER OF THE A0 AND B21 HORIZONS OF A PODZOL

The organic matter of the A0 and B21 horizons of a podzol soil has been oxidized with alkaline permanganate under conditions similar to those employed by Bone et al. (1, 2). Using a slight excess of alkaline permanganate, about 65 per cent of the carbon of the A0 horizon was oxidized to CO2, 23 per cent to oxalic acid and 2 per cent to acetic acid. The remaining 10 per cent resisted oxidation to these products. Under the same conditions 92 per cent of the carbon of the B21 horizon was oxidized to CO2, 7 per cent to oxalic acid and 1 per cent to acetic acid.In order to obtain additional identifiable products less drastic conditions were used. The organic matter of the A0 horizon was oxidized at a KMnO4/organic matter ratio of 4.7-1 and that of the B21 horizon at ratios of 2.5-1 and 5.0-1.The products of oxidation were fractionated by the scheme of Bone et al. (1). While the mean composition of a substantial portion of the CO2-free oxidation products approximated to that of benzene di- and tricarboxylic acids and that of another fraction to saturated open chain acids, numerous attempts to isolate these acids in pure forms were unsuccessful. Reasons for the failure to isolate these acids are advanced.

THE INFLUENCE OF BURNING ON THE SOIL IN THE TIMBER RANGE AREA OF LAC LE JEUNE, BRITISH COLUMBIA: II. CHEMICAL PROPERTIES

The effects of fire on certain soil chemical properties were investigated on soil samples taken from the surface organic layer (O horizon) and the immediately underlying leached mineral layer (A2 horizon) from seven different burns and from corresponding unburned areas present within each burned-over area. Burning resulted in an increase in the pH, total phosphorus content, and CO2-soluble calcium content of the O horizon of most of the soils studied. As a consequence of fire, the O horizon was reduced in organic matter, total nitrogen and carbonic acid-soluble phosphorous and magnesium. Most of the effects of fire upon soil chemical properties were apparently restricted to the O horizon since no significant trends were evident in the underlying A2 horizon.

SEASONAL pH FLUCTUATIONS IN A GREY WOODED SOIL

Seasonal fluctuations in pH values were determined on soil samples from a modal Grey Wooded soil (Cooking Lake series). Samples were collected from the A0, A2, and B1 horizons at regular intervals from May to November. During this period the pH of each horizon varied from neutral to strongly acid. These fluctuations appeared to be related to the soil moisture and possibly to the soil temperature regime.

MINERAL NUTRIENT CONTENT OF SOME FOREST PLANT LEAVES AND OF THE HUMUS LAYER AS RELATED TO SITE QUALITY

The nutrient content of the humus and of some of the plants characteristic of different site classes has been studied. Analyses carried out on fresh healthy leaf material from typical forest plants indicated no differences within a given species that could be related to site quality. Available nutrient content of the A0 horizon collected in the same environment is, however, closely related to the productivity of the sites. It seems, therefore, that the differential accumulation of nutrient elements in the cells of the forest plants studied depends upon the inherent properties of the species rather than on the quantity of available nutrients in the humus on which they grow.

A COMPARISON OF THE EFFECTIVENESS OF VARIOUS EXTRACTANTS FOR ORGANIC MATTER FROM TWO HORIZONS OF A PODZOL PROFILE

A survey was made of the extractive power of 15 reagents for organic matter from the A0 and B21 horizons of a podzol. All were inorganic except disodium ethylene diamine tetraacetate (EDTA-Na2) and their solutions ranged in pH from 1.4 to 13.1. The amount of organic matter extracted varied with horizon and with extractant. While only NaOH removed appreciable amounts from the A0 horizon, Na4P2O7, Na3PO4, NaF, Na2CO3, NaOH, HF and EDTA-Na2 extracted &gt; 80 per cent of the organic matter of the B21 horizon. No organic matter from the A0 horizon extracts passed through a cellulose membrane on dialysis against distilled water whereas the B21 extracts lost from 20 to 70 per cent of their carbon content. The ash content of the non-dialyzable portion of the B21 horizon extracts was high (20–40 per cent), indicating the possible presence of complexes of organic matter with metals such as Fe and Al and with clays. The carbon contents of the same materials ranged between 40 and 50 per cent, suggesting that all extractants removed essentially a similar type of material.

Micro-fungi in Pine Litter

ALTHOUGH a certain amount of work has been carried out on the microbiological characteristics of horizons in podzol soils, there is as yet little relating to the subdivisions of the A 0 horizon. In any such work there are obvious advantages in studying litter derived from a single species. Plantations of Pinus sylvestris have the added advantage that slow decomposition of the litter leads to the accumulation of a considerable A 0 horizon readily divisible into distinct layers. The A 0 horizon of forest soils can be subdivided in the following way : L layer, undecomposed litter; F layer, decomposing but still recognizable litter; H layer, amorphous humus. In cases of considerable accumulation the F layer may be further subdivided into F1, needles dark in colour, often still intact, and F2, needles greyish, fragmentary, compressed1.

Genesis of Some Thick‐Surfaced Brunizemic Soils of Eastern Oklahoma

AbstractThick‐surfaced Brunizemic soils, Taloka silt loam, occur in eastern Oklahoma and adjoining states. A Taloka silt loam profile consists of (1) a dark grayish brown A1 horizon 10 to 20 inches thick; (2) a brown to light brownish gray, soft floury A2 horizon 10 to 14 inches thick containing some black concretions and slightly mottled in the lower part; (3) a dark grayish brown, mottled B21 horizon with dark clay film on peds, blocky, containing some small black concretions, becoming less dark but more clayey below; and (4) mottled, grayish brown, yellowish brown, and strong brown very firm and very slowly permeable clay (C).The following analyses are reported on (1) each of the several horizons of two profiles of typical Taloka silt loam, and (2) the major horizons of an adjoining Teller fine sandy loam: particle size distribution, bulk density, percent organic matter, percent total nitrogen, and pH. Base‐exchange capacity was determined for the &lt; 2µ fractions of each horizon. Heavy, medium, and light mineral determinations were made on the very fine sand and coarse silt fractions of each horizon.The physical, chemical, and mineralogical measurements indicate that the Taloka silt loams possess more than one solum. The data show that the upper and more silty horizons have undergone horizon differentiation under a different regime of soil development than the more clayey and lower horizons.

Sols Bruns Acides of the Northeastern United States

AbstractSols Bruns Acides is the name now used in Belgium, France, and possibly other European countries for a class of soils at the great soil group level. Similar soils have developed under forest vegetation in the Northeastern United States, and it is proposed that the same name be applied here. In the past these soils have been included with Brown Podzolic, weak Podzol, weak Gray‐Brown Podzolic or Red‐Yellow Podzolic soil groups. Morphologically, Sols Bruns Acides have a thin A1 horizon; a paler A2 or A2‐like horizon (possibly a B1 horizon) which is poorly differentiated from the B2 horizon; a B2 horizon with uniform color from top to bottom, weak subangular blocky structure, and silicate clay accumulation not evident or appearing only in traces. Sola of these soils are strongly to very strongly acid and have low base status. Distinction between Sols Bruns Acides and the Gray‐Brown Podzolic and Red‐Yellow Podzolic soils rests mainly on amounts of clay accumulation in the B horizon. Sols Bruns Acides differ from weak Podzols and Brown Podzolic soils mainly in color and structure of the B horizon. The latter have in the upper B horizon strong colors which fade with depth and weak, fine granular structure.

Pedology of an Arctic Brown Profile near Point Barrow, Alaska

AbstractThe Arctic brown profile forms on the medium and coarse textured material of well‐drained sites in the Alaskan Arctic Slope. The profile shows an accumulation of organic matter in the A1 horizon, a weak translocation of Fe, Al, and Mn, and an accumulation of fines in the surface horizon, probably resulting from aeolian activity. Organic matter decreases from 11.48% in the A1 horizon to less than 1% in the A2, A3, and C horizons, and the strongly developed profile colors are thought to be due primarily to this organic matter distribution. C/N ratios of the organic matter vary between 16:1 and 18:1. Base saturation is very low in the surface layer but increases with depth, and free carbonates are present in the lower horizons. Clay composition consists mainly of 2:1 layer silicates with small quantities of kaolinite. No authigenic weathering of primary minerals was detected.Fragmental data indicate that Arctic brown soil forming processes may operate in other tundra and alpine regions of the world.

Field and Laboratory Studies of the Lufkin Soil, a Planosol

AbstractThe Lufkin soil is an extreme type of clay pan Planosol found in a warm‐temperature humid climate and is developed in moderately clayey sediments of deltaic and marine origin. It occupies mainly, smooth erosional upland with gradients dominantly less than 2%. The solum is composed of a relatively thin A1 horizon with an erratically developed thin, vesicular A2 resting abruptly on a dense subsoil of clay loam to clay texture.Analyses were made on four profiles for particle size distribution, pH, organic matter, cation‐exchange capacities, exchangeable cations, surface area, and mineral composition.The &lt; 2µ fraction in the B21 horizons was found to range from 35 to 48%. The largest amount of fine clay (&lt; 0.2µ) occurred in the B21 horizons. Montmorillonite dominated the clay raction in all profiles investigated. Relatively large amounts of exchangeable sodium and magnesium are reported for the lower portions of each soil profile.It is believed that eluviation of the fine clay from the A horizons with subsequent accumulation in the B horizon (illuviation) and clay formation in combination with the relatively large amounts of exchangeable sodium and possibly magnesium, plus a swelling type clay, are responsible for development of the clay pan, but which was the more important is not known.

Frequency Distribution of Clay Minerals in Major Great Soil Groups as Related to the Factors of Soil Formation

AbstractThe frequency distribution or relative abundance of minerals in soils varies with the five principal classes of factors that govern soil formation. The characteristics of the minerals of the parent material, the time factor, climatic factors, relief factors and biotic factors each can be shown to have important independent effects on clay mineralogy of soils under proper circumstances. The soil parent material exerts a control over the frequency distribution of minerals in soils by introduction of the clay minerals into the soil directly, by controlling the course of chemical weathering in the soil through the relative susceptibility of its minerals to weathering, by furnishing abundant divalent metallic cations, by impediment of drainage, or by acceleration of leaching when highly permeable. The time factor is conspicuous as long times give an advanced degree of weathering even in temperate climates. Climate is important, since highly weathered materials inevitably occur as a result of intense leaching in warm tropical and equatorial climates. Relief is important in concentrating leaching water and metallic cations, in affecting oxidation or reduction. The biotic factor affects minerals conspicuously where an A0 horizon develops and resulting cheluviation moves R2O3 out of the A2 horizon.Inherited minerals such as illite, quartz, feldspars, ferro-magnesian minerals, carbonates and gypsum are most abundant in clays of little-weathered parent materials and soils of the zonal Desert, Brown, Chestnut and Tundra soils as well as intrazonal Mountain groups and azonal Regosols and Lithosols. Secondary layer silicate minerals such as vermiculite, secondary chlorite, montmorillonite, kaolinite and halloysite are most abundant in clays of moderately weathered parent materials and soils of the zonal Chernozem, Prairie, Gray—Brown Podzolic, Podzol, Red—Yellow Podzolic, and Low Humic Latosol groups as well as intrazonal Planosol, Rendzina, Dark Magnesium soil, and Wiesenboden groups. Secondary sesquioxide minerals such as hematite, goethite, allophane, gibbsite and anatase and residual resistant primary minerals such as ilmenite and magnetite predominate in the more highly weathered parent materials and soils of the zonal Ferruginous Humic Latosols, Hydrol Humic Latosols, Latosolic Brown, and Ando soils and Laterites, as well as the intrazonal Tropical Savannah and Ground Water Podzol ortstein soils.

Dark Island heath (Ninety-mile Plain, South Australia). III. The root systems

This paper describes the nature of the root systems of the most important members of the heath community. Several variations of tap-root and fibrous root systems were observed. Tap-rooted species were either shallow rooting (1–2 ft) or deep rooting (6 or more feet into the clay subsoil). Two variations of deep tap-rooted species were observed. The tap-root of one decays with age; the laterals of the other produce frequent sucker shoots. In all forms of the deep tap-rooted species an extensive lateral root system was developed within the surface 12 in. of soil — the organic A1 horizon; the tap-root and occasional secondary vertical descended, often unbranched, to the subsoil. The fibrous root system may arise from stem bases, rhizomes, tubers, or underground stocks (caudices). With the exception of underground stocks, which had extensive roots in the A2 and A3 to B horizons, the other forms of the fibrous root systems were confined to the A1 horizon. The marked concentration of roots in the organic A1 horizon was illustrated in dry weight–depth curves. Most of the roots in the A2, and A1 horizons arose from the caudex of Xanthorrhoea australis R.Br.; the remainder were vertical roots which passed directly into the subsoil from the deep-rooted species. About 70 per cent of the species recorded in the heath had morphological characteristics which enabled them to survive a fire and sprout from perennating buds buried under the surface of the ground. Thus, although the aerial organs of the heath were destroyed by fire, the root systems provided a reserve of food and nutrients for the regenerating heath. The dry weight of the root systems was therefore scarcely influenced by fire and thereafter steadily increased in the organic A1 horizon as the stand aged. The presence of root nodules on species of Leguminosae and Casuarinaoeae as well as of haustoria on Exocarpos sparteus R.Br. and Euphrasia collina R.Br. Is recorded.