Seasonal Waterlogging Research Articles

Fragipan formation in argillic brown earths (Fragiudalfs) of the Milfield Plain, north‐east England. III. Micromorphological, SEM and EDXRA studies of fragipan degradation and the development of glossic features

SUMMARYThe micromorphology of eluvial and glossic areas with weak soi1, strength from the upper fragipan, and the upper parts of grey polygonal zones, in some argillic brown earths (Glossic Fragiudalfs) from north‐east England shows unstable void walls stripped of clay with remnants of ferri‐argillans, pale grey grainy clay coatings and darker grainy coatings. These occur alongside loose surface residues of skeleton grains and thin grey fine silt coatings of quartz and muscovite. SEM and EDAX studies of coating surfaces, and optical microscopy, SEM and EDXRA of very thin polished sections, show that some grainy clay coatings form as alteration rims of ferri‐argillans through localized waterlogging, iron oxide loss and micro‐erosion leading to micropitting and disoriented fabrics. The inclusion of coarse clay to fine silt‐sized quartz, feldspar and muscovite in other grainy coatings suggests either alteration of impure ferri‐argillans or accumulation of degradational products derived from elsewhere on void walls. This is more certainly the case for dark grainy coatings in layered compound illuviation coatings adjacent to glossic areas. These fragipans are degrading from the top downwards by processes which are partly a consequence of the effects that the fragipan has on water percolation and root penetration. The destabilization of void walls, the degradation of ferri‐argillans and the remobilization of clay to form glossic features did not begin until seasonal waterlogging in parts of the upper pan was sufficient to mobilize iron.

Genetic Structure and Allozyme-Microhabitat Associations in Bromus hordeaceus

Genetic variation at alcohol dehydrogenase and phosphoglucoisomerase loci in Bromus hordeaceus on the Baltic island of Oland shows substantial spatial structuring among sites several km apart but also among plots within sites on a scale less than ten m. Oland habitats occupied by B. hordeaceus consist of a fine-scale mosaic in which thin soils on well-drained calcareous bedrock are interspersed with depressions containing deeper soil and subject to seasonal water logging. Among sites, the frequency of the Adh-1b-S allele was significantly associated with soil depth and with the cover of mosses and of grasses. The frequency of the Pgi-1b-F allele was significantly associated with soil depth and the Pgi-1b-M allele was significantly associated with soil depth and with the cover of mosses, lichen and grasses (...)

The vegetation of Brazilian ‘murundus’ – the island-effect on the plant community

ABSTRACTThe ‘campos de murundus’ (carthmound fields) are typical landscapes of the cerrado (savanna) region of Central Brazil and are characterized by many rounded earthmounds called ‘murundus’ which are scattered over a grassland surface. As these areas are normally liable to seasonal water-logging, the earthmounds are true habitat islands capable of bearing woody plants typical of the cerrado, which are normally very intolerant of root inundation. The vegetation of an area of murundus field at Cuiaba, in the State of Mato Grosso, Central Brazil, was surveyed for the purpose of evaluating the island-effect on the plant community growing on the mounds/islands. Two main aspects were considered: the influence of the size of the mound and the differences between the types of cerrado occurring on the mounds and on the areas surrounding the murundus field. Most plant species occurring on the mounds were also present in the flora of the surrounding cerrado. However, only a fraction of these species was able to colonize the mounds successfully. The number of species on the mounds was found to be significantly correlated with mound area. Speciesarea relationships were better described with the power model S = C(Az) than with the exponential model S = C + z (logA) (fitted with linear regression). The mound size also had a strong influence on the spatial distribution of the species on the surface of the mounds. The species were organized in an increasing number of concentric topographic belts corresponding to a gradient of soil depth above the Hooding level.

Sedimentology and paleopedology of Miocene alluvial deposits at the Paşalar Hominoid site, Western Turkey

Miocene age alluvial deposits at the Paşalar Hominoid site in Western Turkey consist of a fossil-bearing green sand unit and two drab-colored, calcareous paleosols that sandwich the fossiliferous bed. The green sand unit contains a significant amount of bone chips and teeth. High concentrations of gravel, bone and teeth occur in, and directly above, large pothole shaped bodies which extend from the green sand down into the underlying calcareous paleosol. Gravel pipes emanating upward from the vicinity of these “potholes” are interpreted as fluid escape structures. The fossiliferous green sand bed is interpreted as the deposit of a silty, pebbly sand flow ( en masse emplacement) on the basis of its overall normal grading, vague horizontal layering, grain and matrix supported fabrie, and abundant fluid escape structures. The enigmatic potholes may have been holes produced by the burning out of tree trunks in the soil; they match modern examples well. The two calcareous paleosols, termed the lower and upper calcareous silt, are very much alike and represent a soil-forming environment where both clay formation and calcification took place. Pedogenic features common to both paleosols include green colors, high clay content, clay skins and clay slickensides, an unusually great thickness (about 2 m after compaction) and an abundance of golf-ball-sized calcareous nodules. The gleyed nature of the paleosol indicates a climate with seasonal waterlogging. Abundant calcareous nodules in the paleosol profiles indicate a pronounced dry season and clay formation indicates a warm, humid season. Up-section from the fossil beds is the main alluvial sequence of thick non-calcareous siltstones and cobble conglomerates exposed in gullies to the northeast of the exacavation site. The siltstones are pervasively mottled red and green. They have abundant soil structures including root traces, blocky peds and cutans. These massive, mottled siltstones are interpreted as paleosols of a generally well drained floodplain and the interbedded conglomerates are interpreted as braided stream channel deposits. The main alluvial sequence has dips of less than 3° whereas the fossil beds and their clayey paleosols dip between 7° and 10°. Thus there was an episode of tilting between the deposition of the two sequences. A riverine levee and floodplain depositional environmental is interpreted for the Paşalar fossil beds based on the gleyed paleosol profiles and the onlap of channel fill and levee deposits on both the fosiliferous sand unit and upper calcareous silt. They probably formed in a low-lying stream side location in a wet-dry monsoon climate, similar to semi-arid to semi-humid areas in the Punjab province of India. On the basis of comparison with modern soils from the Punjab, similar Paşalar paleosols are classified as intermediates between Calciorthids and Ustochrepts that have gleyic properties.

The variation of soil water regime, oxygen status and rooting pattern with soil type under Sitka spruce

SUMMARYSoil water regime, oxygen status and rooting pattern under Sitka spruce were characterized in five soil types: a waterlogged peaty gley, a peaty gley, a flushed peaty gley, a surface water gley and a brown forest soil during 1982. The waterlogged peaty gley had a high water‐table which only dropped below 30 cm depth for 46 d during the summer. Below the water‐table the profile was anoxic and rooting was restricted to a depth of 12cm. The peaty gley experienced seasonal waterlogging with a winter water‐table around 15cm depth. Roots that grew further down the profile during the summer as the topsoil dried to –100 kPa matric potential were later killed when the water‐table rose. The top 30 cm of the flushed peaty gley remained oxygenated even below the water‐table. Roots survived below the winter water‐table. The top 30 cm of the surface water gley and brown forest soil were freely draining and remained aerated throughout the year. The platinum electrode polarographic method demonstrated that there was a sharp transition to anoxic conditions just above the water‐table at the first two sites.

Effects of waterlogging and subsequent drainage of a pasture soil on phosphate sorption, extractable phosphate and oxalate-extractable iron

Undisturbed cores of a pasture soil from the central tablelands of New South Wales were waterlogged for periods varying from 4 to 42 days and then drained to simulate seasonal waterlogging. Phosphate sorption, Bray 1 extractable phosphate and oxalate-extractable iron levels were measured before watering, at the end of waterlogging and up to 90 days after draining. Increasing the duration of waterlogging increased the logarithms of phosphate sorption and Bray 1 extractable phosphate linearly, but the response equation of log oxalate iron was significantly quadratic. When drained, all three levels fell, but the positive sorption response to waterlogging remained 90 days after draining. These results are consistent with those from previous studies that found phosphate solubility to be associated with the reduction of iron during waterlogging and its subsequent oxidation on drying. The agronomic implication of the findings for superphosphate topdressing of seasonally waterlogged soils is discussed.

Albic Neoskeletans in Argillic Horizons as Indices of Seasonal Saturation and Iron Reduction

AbstractSignificant periods of seasonal waterlogging in some soils of the Texas Coastal Plain have gone unrecognized because the soils lack low (≤ 2) chroma colors. A study was conducted in two soils along a forested toposequence of Alfisols to identify morphological features other than color that are indicative of ground water saturation and Fe reduction. The duration of saturation and Fe reduction had been determined previously for each soil of the toposequence. Iron nodules (> 2 mm diam) and neocutanic albic materials (albic neoskeletans) were sampled and their abundance determined. Albic neoskeletans were also characterized with respect to total Fe content, particle size distribution, and color. Sesquioxide nodules within portions of the argillic horizon had no consistent relationship to the soil structure and were found both in zones of Fe loss and accumulation. This indicated at least some nodules were relict features and that nodules could not be used for moisture regime identification in these soils. Albic neoskeletans along ped surfaces and root channels formed in place by a loss of clay and free Fe from the surfaces of macropores. Most albic neoskeletans were not overlain by other cutans and all evidence indicated they formed under the current moisture regime in each soil examined. Albic neoskeletan abundance was directly related to the duration of Fe reducing conditions, but not to the duration of saturation. Greatest development of these features occurred in a soil with a perched water table in horizons that were Fe reduced for 55 to 146 d. It is suggested that albic neoskeletans be used as diagnostic criteria for water saturation and Fe reduction despite their moist color chromas of 4 or less. It is proposed that albic neoskeletans be used, when low (≤ 2) chroma colors are absent, to identify aquic intergrades in Paleudalfs.

Establishment techniques for radiata pine on poorly drained soils deficient in phosphorus

Summary The techniques investigated for establishment of Pinus radiata plantations on soils near Neerim East, Victoria, deficient in phosphorus and subject to seasonal water-logging, included three methods of site preparation (disc ploughing, deep ripping and a combination of the two) in the presence and absence of localised applications of superphosphate. Four sites with contrasting native vegetation were examined, but characteristics of the dominant vegetation proved to be poor indicators of site potential for early growth of P. radiata following the cultivation and fertiliser application. A localised application of superphosphate was found to be essential for. satisfactory survival and early volume growth. Limitations of such an application are discussed. The early growth of fertilised trees on sites receiving the combination of ripping plus ploughing was considerably greater than that obtained from either ripping alone or ploughing alone. Insufficient cost/benefit data were available to determine whether the additional cost associated with this combination of methods of site preparation is justified. However, ploughing alone is preferred to ripping alone on the basis of growth response being more or less proportional to the cost of these respective treatments and an expected lower overall cost of controlling woody weeds.

Environment and provenance in the development of recent alluvial deposits in epirus, nw greece

AbstractThe valleys of Epirus, in NW Greece, are floored by alluvium laid down in historical times. In an attempt to evaluate the relative importance of diagenesis and of parent material in determining its local character, the alluvium was compared with the principal source deposits, namely the red beds of the late Quaternary Kokkinopilos Formation and the brown Mediterranean soils that have developed on flysch outcrops. Rehydration of the haematite pigment after deposition coupled with silt‐clay depletion during redeposition of the red beds is responsible for the drab colour of the valley‐floor deposits in limestone catchments. Where the alluvium was derived from brown soils, little mineralogical change has occurred. Some reduction and mobilization of iron has affected Kokkinopilos beds still in place, possibly during periods of seasonal waterlogging under oak forest, to produce a veining pattern akin to that found in pseudo‐gley soils.

Weathering and soil formation on dolerite in Tasmania with particular reference to several trace elements

The mineralogy and chemistry of weathering and soil formation have been studied at 17 widely separated sites with contrasting climatic conditions on comparatively uniform dolerite in Tasmania. The clay and fine sand mineralogy of the soils has been related to their degree of weathering. These studies have shown large chemical and mineralogical changes accompanying the initial stages of weathering in some krasnozem soils. The reorganization of cobalt, zirconium, nickel, copper, molybdenum, manganese, and zinc during genesis of four soil groups has been considered in terms of the factors involved. Some of these results indicate that the clay horizon of the podzolic soils has probably been formed by weathering in situ. Seasonal waterlogging in certain horizons has strongly mfluenced the chemistry and mineralogy of weathering in many of these soils. This study has shown that the composition of the parent material has only influenced the geochemistry of trace elements in less weathered soils and that pedogenic factors assumed greater significance as the soils became more strongly weathered. Geomorphic processes had a marked influence on the geochemistry of some soils by the truncation of mature soil profiles.