Acid Brown Forest Soil Research Articles

Approaches to the development of environmental standards for the content of petroleum hydrocarbons and Pb, Cr, Cu, Ni in soils of Greatest Caucasus

<p>The development of tourism and leisure infrastructure results in a continuous increase of anthropogenic impact on soils of wet and dry subtropics of the Greatest Caucasus. It is very important for the region to preserve the sustainable functions of soils and ecosystems, maintain a comfortable life and recreation environment create environmentally friendly agricultural products. It is conducted studies to determine the limits of resistance of soils in wet and dry sub-tropics to priority pollutants, especially petroleum hydrocarbons and heavy metals (Pb, Cr, Cu, Ni). It was found that the soils of wet and dry subtropics for resistance by Pb, Cr, Cu, and Ni are located as follows: south-ern chernozem > typical sod-carbonate soil ≥ brown typical soil ≥ brown carbonate soil = brown leached soil ≥ leached sod-carbonate soil = yellow soil >acid brown forest soil ≥ acid brown forest podzolized soil. In terms of the degree of resistance to oil pollution, studied soils create certain series: brown carbonate ≥ brown typical = sod-carbonate leached ≥ sod-carbonate typical > southern chernozem ≥ yellow soil ≥ brown leached soil > acid brown forest soil = acid brown forest podzolized soil. Heavy metals by ecotoxicity to the soils of wet and dry subtropics from the following series: Cr> Cu ≥ Ni = Pb. Based on the degradation of ecological functions of soils, we offer regional standards of the maximum permissible content of Pb, Cr, Cu, and Ni for the main soils of wet and dry subtropics.</p>

Biodiagnostics of Resistance to the Copper (Cu) Pollution of Forest Soils at the Dry and Humid Subtropics in the Greater Caucasus Region

Forest ecosystems perform important forestry and ecological functions. However, mining and processing companies cause significant soil contamination by heavy metals, in particular, copper (Cu). The resistance of nine types and subtypes of forest soils of the dry and humid subtropics in the Greater Caucasus region to Cu contamination at concentrations of 100, 1000, and 10,000 mg/kg was evaluated for the first time following the most sensitive and informative biological (microbiological, biochemical, and phytotoxic) indicators via a laboratory simulation study. Contamination was simulated under laboratory conditions. The series of forest soils was established following their resistance to Cu pollution: brown leached soils (Haplic Cambisols Eutric) = brown typical soils (Haplic Cambisols Eutric) > brown carbonate soils (Haplic Cambisols Eutric) = sod-carbonate typical soils (Rendzic Leptosols Eutric) ≥ yellow soils (Albic Luvisols Abruptic) ≥ leached sod-carbonate soils (Rendzic Leptosols Eutric) > brown forest slightly unsaturated soils (Haplic Cambisols Eutric) > acid brown forest soils (Haplic Cambisols Eutric) > acid brown forest podzolized soils (Haplic Cambisols Eutric). Regional environmentally safe standards for the Cu content in forest soils of the dry and humid subtropics of the Greater Caucasus were proposed: for brown typical soils, brown leached soils, brown carbonate soils, brown forest slightly unsaturated soils, sod-carbonate typical soils, leached sod-carbonate soils, and yellow soils, the rMPC was 100 mg/kg; for acid brown forest soils and acid brown forest podzolized soils, the rMPC was 70 mg/kg.

Microbiocenosis characteristics of agrogenically altered acid brown forest soils in humid subtropics of Russia

Under conditions of perennial cropping of industrial tea crop on acidic brown forest soils of the Black Sea coast of Russia, the following were investigated: number of bacteria, of actinomycetes (mainly the Streptomyces genus) and of micromycetes (saccharomycetes), seasonal dynamics and functional activity of the microbial complex during period of 2008-2019. Stationary experiments were launched in various backgrounds of mineral fertilizer application. The experiment was accompanied by the use of generally accepted recommended techniques for microbiological studies. As follows from the analysis of the data obtained, it was established that the long treatment period of mineral fertilizers at doses from N200P60K50 to N600P180K150 in given soil-climatic conditions under the tea crop contributed to significant decrease in the number of actinomycetes and nitrogen fixing bacteria of the Beijerinckia genus vs. the control variant (without fertilizers). The most significant decrease in the number of micromycetes was revealed immediately after the application of mineral fertilizers at a dose of N600P180K150. After 2 months, the number of this group of soil microorganisms was built back. Under the impact of both medium and high doses of mineral fertilizers, the functional activity decrease of soils (CO2 emission and potential nitrogen fixation activity) was noted.

Nehézfém- és egyéb toxikus mikroelem-terhelés tartamhatása a talajból mért visszanyerési százalékuk alakulására szabadföldi kísérletekben

Összefoglalás Dolgozatunkban Kádár Imre 1991 tavaszán meszes csernozjom talajon 13 potenciálisan toxikus mikro- / károselem (Al, As, Ba, Cd, Cr, Cu, Hg, Mo, Ni, Pb, Se, Sr és Zn) 0-90-270-810 kg ha−1 szintjeivel beállított szabadföldi tartamkísérlete 1-20. évi talajvizsgálati-, illetve talaj visszanyerési százalék eredményeit értékeltük. A LE-oldható (NH4-acetát+EDTA) és „összes” (cc.HNO3+cc.H2O2) elemtartalmak aboszlút értékeinek változásai mellett figyelemmel kísértük az elemek visszanyerési százalékainak időbeni változásait is. A kísérlet 4. évében a legnagyobb talaj LE-oldható visszanyerési százalékokat a kationos formában kiadott elemek esetében kaptunk, míg az anionos formában kijuttatottak (Se, As, Mo, Cr) az elemsorrend második felében, illetve a végén helyezkedtek el. A kísérlet 18. évére a legtöbb elem LE módszer szerint kimutatott oldhatósága, és így visszanyerési százaléka kisebb-nagyobb mértékben csökkent. Legnagyobb csökkenéseket a Sr, Pb, Zn, míg legkisebbeket a Mo, Cr és Cd elemek mutattak. A tápláléklánc szennyeződése szempontjából kedvezőtlen, hogy a kijuttatott karcinogén Cd jelentős hányada maradt a könnyen oldható frakcióban, és ez a frakció a 14 év alatt is csak minimálisan csökkent a meszes csernozjom talajon. Az elemek átlagában, a LE-oldható elemtartalomban mért visszanyerési százalék 1994-ben 41%, míg 2008-ban 22% volt. A 14 év alatt tehát az átlagos, LE-oldható elemtartalomban mért visszanyerési százalék 19 abszolút %-kal csökkent, azaz gyakorlatilag megfeleződött. Az egyes elemek „összes” elemtartalomban a kísérlet 4. évében mért visszanyerési százalékának sorrendje a LE-oldható tartalmaknál leírtakhoz hasonlóan alakult; a legkisebb visszanyerési százalékokat itt is az anionos formában kijuttatott elemeknél kaptunk. Míg a LE-oldható tartalmaknál a Hg, addig az „összes” elemtartalmaknál a Cd, mint nehézfém ékelődött be az anion formában kijuttatott elemek közé. A kísérlet 18. évében az „összes” elemtartalomban mért visszanyerési százalékok esetében a legnagyobb csökkenéseket a Se, Sr, Pb, míg legkisebbeket a Cd, Mo és Cr elemek mutattak. Az utóbbi három elem közül humán egészségügyi szempontból a Cd tekinthető a legveszélyesebbnek. Az elemek átlagában, az „összes” elemtartalomban mért visszanyerési százalék 1994-ben 81%, míg 2008-ban 49% volt. A 14 év alatt tehát az átlagos összes elemtartalomban mért visszanyerési százalék 32 abszolút %-kal Csökkent. A meszes csernozjom, meszes homok, és savanyú, agyagos vályog textúrájú barna erdőtalajon beállított károselem-terheléses tartamkísérlet adatainak tanúsága szerint a LE-oldható elemtartalomban kifejezett, és az „összes” elemtartalomban kifejezett visszanyerési százalékok egymáshoz viszonyított aránya inkább elem-, mint talajtulajdonság-függő. Úgy találtuk, hogy a három, egymástól jelentősen eltérő tulajdonságú talajon viszonylag azonos időben, azonos mennyiségben és azonos formában kijuttatott potenciálisan káros elemeknek a LE-oldható elemtartalomban mért visszanyerési százalékok és ”összes” (cc.HNO3+cc.H2O2-oldható) elemtartalomban mért visszanyerési százalékok arányainak sorrendje állandó, tehát a talajtulajdonságoktól független volt. Ezen felismerés alapján fogalmaztuk meg a Szabó-Csathó-Kádár-féle potenciálisan toxikus talaj-mikroelem kiterjeszthetőségi szekvens megnevezést. Természetesen ezen hipotézisünket még számos más talajtípuson, hasonló feltételekkel beállított tartamkísérletben is szükséges lenne bizonyítani.

The interrelation of changes in acid-basic properties of acid brown forest soils in the Russian subtropics during agrogenic acidization under tea culture

The interrelation of changes in acid-basic properties of acid brown forest soils in the Russian subtropics during agrogenic acidization under tea culture

Biologically Active Organic Matter in Soils of European Russia

Experimental and literature data on the contents and stocks of active organic matter in 200 soil samples from the forest-tundra, southern-taiga, deciduous-forest, forest-steppe, dry-steppe, semidesert, and subtropical zones have been generalized. Natural lands, agrocenoses, treatments of long-term field experiments (bare fallow, unfertilized and fertilized crop rotations, perennial plantations), and different layers of soil profile are presented. Sphagnum peat and humus–peat soil in the tundra and forest-tundra zones are characterized by a very high content of active organic matter (300–600 mg C/100 g). Among the zonal soils, the content of active organic matter increases from the medium (75–150 mg C/100 g) to the high (150–300 mg C/100 g) level when going from soddy-podzolic soil to gray forest and dark-gray forest soils and then to leached chernozem. In the series from typical chernozem to ordinary and southern chernozem and chestnut and brown semidesert soils, a decrease in the content of active organic matter to the low (35–75 mg C/100 g) and very low (<35 mg C/100 g) levels is observed. Acid brown forest soil in the subtropical zone is characterized by a medium supply with active organic matter. Most arable soils are mainly characterized by low or very low contents of active organic matter. In the upper layers of soils, active organic matter makes up 1.2–11.1% of total Corg. The profile distribution of active organic matter in the studied soils coincides with that of Corg: their contents appreciably decrease with depth, except for brown semidesert soil. The stocks of active organic matter vary from 0.4 to 5.4 t/ha in the layer of 0–20 cm and from 1.0 to 12.4/ha in the layer of 0–50 cm of different soil types.

Ecological evaluation of oil-contaminated soils (Sakhalin) using enchytraeidae

The ecological status of oil-contaminated soils of Sakhalin and their background analogues has been evaluated with the use of soil invertebrates. The survival rates of Enchytraeus albidus in soils with different textures and the contents of organic carbon and nutrients have been compared. The indicative role of soil mesofauna (Enchytraeus albidus) for the ecological evaluation of oil-contaminated soils with due account for their properties has been shown. The permissible residual concentration of oil hydrocarbons in some soils of Sakhalin—acid brown forest soils (Umbrisols), high-moor peat soils (Histosols), acid meadow alluvial soils (Fluvisols), cultivated meadow soddy soils (Anthrosols), and mucky-podzolic surface-gleyed soils (Gleysols)— has been determined from data on the response of Enchytraeus albidus to different levels of the soil contamination with oil hydrocarbons.

Study of the Potentially Mineralized Nitrogen Content and Nitrogen Supply by Soil Incubation Method in a Long-Term Field Experiment in East Hungary

The formation and fate of soluble nitrogen (N) forms and their response to organic-matter mineralization is not obvious yet, and results are often inconsistent despite intensive research. The available N supply of the soil is very important for plant nutrition and environmentally sound N fertilization. The determination of actual N supply is very important for sustainable agriculture in Hungary, especially in acidic sandy soils, which are very sensitive to environmental effects and inefficient human treatment. Therefore, the aim of this article is to provide further information about N mineralization processes and organic–mineral interactions of soil. To establish the potentially mineralized N content and available N supply of soil, a biological (incubation) method was carried out an acidic brown forest soil of the Nyírlugos long-term field experiment in Hungary. The incubation was carried out in the laboratory with differently treated soils of the long-term field experiment to investigate the effect of treatments on N mineralization processes of soil. The incubation period was 16 weeks long. The pH and the easily soluble mineralized and organic N fractions of soil were measured periodically from leached solution (0.01 M calcium chloride; CaCl2). The leaching process was repeated after 2, 3, 5, 7, 9, 12, and 16 weeks. The potentially mineralized N content of soil and the actual rate of N mineralization were calculated from periodically collected data. The results of the incubation method can be summarized as follows: the kinetics of incubation of 0.01 M CaCl2 soluble organic N is similar to mineral N; 0.01 M CaCl2–soluble N fractions were mainly in inorganic forms in the incubation period but the content of the organic form was significant too; and the mineralization rate is greater where the microbiological activity of the soil is expressed and the soil properties are more favored as a result of applied treatments.

Mineralogical composition of the clay fraction in acid brown forest soils under tea plantations subjected to the long-term mineral fertilization in Russian subtropics

Swelling minerals of the montmorillonite group predominate in the clay fraction of acid brown forest soils under tea plantations; illite and quartz are present in smaller amounts; small amounts of chlorite-like structures are also found. A decrease in the content of swelling mineral and a deterioration of their crystallization degree (especially in the upper horizons) take place upon the long-term application of mineral fertilizers at high rates; also, the accumulation of illite takes place. These processes attest to the beginning of degradation and/or removal of montmorillonite minerals (the most finely dispersed and hydrophilic clay minerals) under the impact of a significant decrease in pH because of the high rates of physiologically acid fertilizers in combination with illitization under the impact of potassium application.

Results of a 30-year-old fertilisation experiment

The long-term mineral fertilisation experiment set up on acidic brown forest soil in Gödöllő in 1972 has made it possible over the years to answer a number of questions. It became clear that, in general, increasing rates of NPK fertilisation only caused a significant increase in the yields obtained in the crop rotation at lower rates (150–300 kg NPK/ha). As time went on, rates higher than this caused yield depression. The continuous application of high fertiliser rates led to a substantial increase in the P and K contents of the ploughed layer and in the quantity of nitrate accumulating in the 3 m soil profile. An increase in the quantity of nutrients was associated with a reduction in the pH and in the content of Ca and Mg. When mineral fertilisation was omitted for six years, there was a substantial reduction in the P and K contents of the ploughed layer.

Impact of rainfall, liming, nitrogen (N), phosphorus (P2O5), potassium (K2O), calcium (CaO), magnesium (MgO) mineral fertilization on triticale (×TriticosecaleWittmack) yield in a monoculture in Hungary

The natural climate variability may be masked by the anthropogenic made global warming, today. With a warmer climate, drought and excess rainfall conditions could become more frequent and longer lasting. The potential increase of the hazards result stresses and high costs in cereal production. For this reason a long-term study was conducted on a sandy acidic lessivated brown forest soil; WRB: Haplic Luvisol in the 44 year old Nyirlugos Field Trial (NYFT) in a Hungarian fragile agroecosystem in Nyirseg region (N: 470 41’ 60, and E: 220 2’ 80,) on triticale (× Triticosecale Wittm.) yield between 1999 and 2006. In 1962, at the trial set up the soil had the following agrochemical properties: pH (H 2 O) 5.9, pH (KCl) 4.7, hydrolytic acidity 8.4, hyl 0.3, humus 0.7%, total N 34 mg kg −1, ammonlactate (AL) soluble-P 2 O 5 43 mg kg −1, AL-K 2 O 60 mg kg −1 in the plowed (0–25 cm) layer. The trial consisted of 32 × 4 = 128 plots in randomised block design. The gross plot size was 10 × 5 = 50 m 2. The average fertilizer rates in kg ha −1 year −1 were nitrogen 75, phosphorus 90 (P 2 O 5), potassium 90 (K 2 O), calcium 437.5 (CaCO 3) and magnesium 140 (MgCO 3). The groundwater table had at a depth of 2–3 m below the surface. During drought conditions the respective yield of the control areas was −25% less than for average years. The application N alone or NP and NK treatments led to yield reduction of −19.7%, while that of NPK, NPKCa, NPKMg and NPKCaMg caused an −28.3% yield drop. In the wet years the yield decreased by −22.2% on the unfertilized soils; in case of the N, NP and NK nutrition the yield dropped with an −14.1%; and the yield increased at 13.8% on NPK, NPKCa, NPKMg and NPKCaMg treated plots. Yield dropped in the very wettest year −43.1% on control soils; −39.3% of N, NP and NK loadings, and −35.8% on NPK, NPKCa, NPKMg and NPKCaMg treatments to those in the average year. The relationship between rainfall quantity during the vegetation period and N, P, K, Ca, Mg nutrition and yield was characterised by polynomial correlation (control: R = 0.7212***, N: R = 0.7410***, NP: R = 0.6452***, NK: R = 0.6998***, NPK: R = 0.5555***, NPKCa: R = 0.5578***, NPKMg: R = 0.4869**, NPK CaMg: R = 0.4341**). However, total regression coefficients ranged from 0.43 to 0.74 in depence on the different nutrient application. Maximum yields of 5.8–6.0 t ha −1 were achieve in the rainfall range of 580–620 mm. At values above and below this domain of the precipitation the grain yield reduced quadratically. So, it can be stated that both drought and excess rainfall conditions resulted dramatically significant negative effects between fertilization (N, P, K, Ca, Mg) and triticale yield.

The humus status of brown forest soils and its changes upon intensive tea growing in the subtropical zone of Russia

Changes in the humus status of acid brown forest soils used for tea growing have been studied in a long-term stationary experiment after 20 years of the application of mineral fertilizers in increasing doses. It is shown that long-term tea growing has resulted in a reliable increase in the humus content within the upper cultivated horizon (Ap, 0–40 cm) at the expense of the nonhydrolyzable fraction of humus (humin) and the first fractions of humic and fulvic acids. The fractional composition of humus has changed against the background of a stable fulvate type of humus (Cha/Cfa < 0.5). The portion of the first fraction of humic and fulvic acids in the total amount of humus has increased, as well as the portion of the first fraction of humic acids in the total amount of humic acids. These changes are due to the enhanced humification of plant residues with a parallel decrease in the contents of the second (Ca-bound) and third (bound with clay and stable sesquioxides) fractions of humic substances.

Az algériai nyersfoszfát és a szuperfoszfát hatásának vizsgálata

The effect of increasing rates of superphosphate manufactured from Kola apatite, marketed in Hungary in the early 90s, and basic rock phosphate from Algeria on the Cd, Cr, Sr, Mn, Ni, Al, Co and Mo concentrations in the grain and by-products of spring barley was investigated in a pot experiment involving three acidic soils from Hungary and one each from Slovakia, Romania and Algeria. The rock phosphate used in the pot experiment contained three times as much Cd and twice as much Cr as is currently permitted in Hungary. Nevertheless, neither of these elements could be detected in the grain yield of barley. The chromium content in the by-products was also below the detection limit in all the treatments on less acidic soils. Even on extremely acidic soils there was only a detectable concentration of chromium in treatments where the development of spring barley was severely retarded. Cadmium, however, was detectable in the by-products on all the soils, in a concentration that depended primarily on the properties of the initial soils and the rock phosphate rates applied. Cobalt could not be detected in the grain yield on any of the soils, and nickel only on extremely acidic brown forest soil with alternating thin layers of clay in treatments where the underdeveloped plants produced a very low grain yield. In the by-products nickel, like chromium, was only present in detectable quantities in the underdeveloped plants growing on extremely acidic soils. On the latter soils cobalt was detected in the by-products in all the treatments, but in healthy plants its concentration was an order of magnitude lower than in retarded plants. Molybdenum was only detected in the grain yield of spring barley on weakly acidic soils, but was present in the by-products on all soils in treatments where healthy plants of spring barley developed. Manganese, aluminium and strontium were found in detectable quantities in plants in all the treatments on all the soils. On the majority of soils the concentration in the by-products was an order of magnitude higher than in the grain. Naturally the plant concentrations of the various elements were influenced by the quantities introduced into the soil with the P fertilizer (Sr, Cd) and by the extent to which the pH changed as the result of the P fertilizer (Cr, Co, Ni, Mo, Cd, Mn and Al). The Ni, Co, Cr, Al and Mn concentrations of the retarded plants growing on extremely acidic soils was several times higher than that of healthy plants (Treatments 9-12). On such soils the rates of basic rock phosphate applied in these treatments served not only as P fertilizer but also as liming agents, exerting a favourable effect by reducing the acidity of the soil and thus the availability of the potentially toxic elements. In agreement with observations found in the literature, the results of the pot experiment on spring barley indicated that heavy metals and potentially toxic elements were accumulated in the vegetative organs of barley, rather than in the grain yield. On soils where the lower pH caused by P treatment increased the availability of potentially toxic elements, plant concentrations were higher, emergence was poor, the plants were retarded and no grain yield was produced. These results provide an indication of the processes to be expected when soils become more acidic.

Fertilisation Effect on Quantity of 0.01 M CaCl2 Soluble N-Forms in a Long-Term-Small-Plot Experiment

long-term experiments have an opportunity to investigate the effects of fertilization and plant nutrition. The paper reports the results achieved in the 39th years of a long-term-small-plot fertilisation and liming experiment set up on acidic sandy brown forest soil in the Nyírség region. From the 32 treatment, four replications, altogether 128 plot experiments with 10 treatments are summarized. We took samples after harvest of triticale, in August.We used a reliable method (segmented continuous flow analysis) to determine different (easily mobilized - 0.01 M CaCl2 soluble) N-forms of soil. The 0.01 M CaCl2 soluble inorganic and total N content and the UV digestable organic-N form of soil were determined by this method.The results are summarized below:– The mineralized-N (Nmin.) content of soil increased with dose of nitrogen treatment. Liming treatments increase the amount of Nmin.– The maximum content of easily mobilize organic-N-fraction was found in the upper (0-20 cm) layer. This fact due to the large amount of crop and roots.– Changing of content of 0.01 M CaCl2 soluble total-N-forms due to N doses.– The ratios of these N forms are variable. It is very important that the content of organic N fraction is not negligible and this fraction plays a main role in the plant nutrition.

Processes controlling silica concentration in leaching and capillary soil solutions of an acidic brown forest soil (Rhône, France)

Chemical analysis of leaching and capillary soil solutions collected at different soil depths was performed on a monthly basis for several years at the Vauxrenard site (Rhône, France). The seasonal variations in dissolved silica (Si) indicated considerable differences whether contained in leaching or capillary soil solutions. In capillary solutions, the maximum and minimum Si concentrations occurred in the summer and winter, respectively, while the opposite trend was observed with leaching soil solutions. In both solutions types, significant relationships may be obtained between Si concentration and soil temperature ( T) and, to a lesser extent, H + concentration. Evaporation or evapotranspiration had little effect on Si in capillary solutions, limited to the upper soil layers. An inverse relationship between Si and T found in leaching solutions indicated that weathering did not control Si concentration. In contrast, a positive relationship between Si and T found in capillary solutions was consistent with this process. This was reinforced by a significant relationship obtained between logSi and pH, which was consistent with surface-controlled and proton-promoted weathering. Calculated apparent activation energy and reaction order with respect to pH were both consistent with muscovite at the laboratory scale. It is suggested that Si concentration in leaching solutions was controlled mainly by diffusion of aqueous silica (essentially orthosilicic acid) from capillary solutions in relation to soil drainage. Thermodynamic calculations showed that the temperature-dependence of the solubility of Si-containing secondary phases did not significantly control Si concentration in both soil solution types. However, it was calculated that the reversible formation of some hypothetical siliceous phases (Si/A1>1) proceeded at relatively slow rates, thus limiting their impact on Si concentration. Kinetic calculations showed excellent results by correlating Si concentration in capillary solutions to specific weathering rate for primary soil silicates. In agreement with most of the statistical analysis, soil temperature appeared to be the main driving force for chemical weathering. Protons (H +) had a significant influence in the deeper soil horizons as well as in the seasons corresponding to lesser soil temperature variations. An important effect of organic ligands and particularly of low molecular weight compounds on weathering may explain larger Si concentration observed in the upper soil layers.

Impact of Tilia platyphyllos Scop., Fraxinus excelsior L., Acer pseudoplatanus L., Quercus robur L. and Fagus sylvatica L. on earthworm biomass and physico-chemical properties of a loamy topsoil

Impact of hardwoods of different humus forms on earthworm biomass and physico-chemical properties of the topsoil of a loamy acid brown forest soil after a time-span of 60–65 years was examined in the Forest of Halle near Brussels. Three sites were selected in which homogeneous stands of mull-forming tree species ( Tilia platyphyllos Scop., Fraxinus excelsior L. and Acer pseudoplatanus L.) were compared with adjacent stands of Fagus sylvatica L. and/or Quercus robur L. where a mullmoder had developed. Total earthworm biomass was conspicuously higher at the sites that supported Tilia and Acer as mull-forming hardwoods. Study of soil acidity revealed that there were marked differences in pH and base saturation in the A- and E-horizon between hardwoods developing different humus forms. The topsoil beneath mull-forming hardwoods was generally higher in pH and base saturation with the largest differences being displayed between Tilia and Fagus/ Quercus. C/N ratios were significantly lower in the topsoil under Acer. Significant differences in physical soil properties among humus form were also evident. The A-horizon under mull-forming species was higher in total porosity, aeration porosity and saturated hydraulic conductivity. The bulk density was only significantly lower under Fraxinus. The E-horizon of the mull stands was lower in bulk density and higher in aeration porosity but this was linked by a reduction in water-filled porosity. The study indicated that mull-forming tree species differed in ability to improve or maintain productivity of the studied soil type.

Vertical distribution of low molecular weight aliphatic carboxylic acids in some forest soils of Japan

SummaryLow molecular weight organic acids are widespread and reactive in soils, but their distribution among mineral horizons is uncertain. We investigated the distribution of low molecular weight aliphatic carboxylic acids (LACAs) in three Japanese forest soils, two Acid Brown Forest soils and one Podzolic soil. The total LACAs ranged from 207.3 to 411.8 μmol kg–1 and were abundant in the lower horizons as well as in the surface horizons of these soils. The illuvial horizons of the Podzolic soil were rich in adsorbed oxalic acid and citric acid. Total LACAs were similar in the two subtypes of Brown Forest soils derived from different parent materials but formed under similar vegetation and climate, and were larger than that in the Podzolic soil. Among the volatile LACAs, formic acid and acetic acid dominated the moist horizons containing much organic material, whereas the non‐volatile LACAs, the most abundant being oxalic acid and citric acid, increased in the subsurface horizons. The distribution of water‐soluble LACAs in the Brown Forest soil profiles was closely correlated with soil acidity.

Fixation of radiocaesium in an acid brown forest soil

SummaryThe 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.

Downward movements of dolomite, kieserite or a mixture of CaCO3 and kieserite through the upper layers of an acid forest soil

Liming and fertilization are important tools for improving the chemical status of acid, base poor forest soils. The downward movement of dolomite, kieserite and a mixture of CaCO3 and kieserite was investigated by monitoring the leachates and exchangeable cation composition from single and combined horizon columns, reconstructed from an acid brown forest soil profile (0-15 cm). Upon entering the soil, Mg ions from kieserite displaced base cations and acidity (H and Al ions) from exchange sites, which subsequently moved down with the mobile SO42- anions. Total leaching during the initial SO42- pulse was similar with the CaCO3 + kieserite mixture. Compared to the single kieserite treatment, the joint application of CaCO3 greatly increased the proportion of Ca in the leachates from all horizons. It also decreased the leaching of acidity from the surface Oe horizon and prevented pH from dropping under this layer. With both treatments, the redistribution of magnesium with SO42- anions resulted in a rapid increase in exchangeable Mg contents throughout the studied columns. Due to the important charge increase in the Oe horizon and to kinetic restraints imposed on dissolution, downward movement of Ca and Mg ions from dolomite was very limited. Mg was however much more mobile than Ca. In the CaCO3 + kieserite and dolomite treatments, the migration of alkalinity and base cations with time was associated with a decrease in exchangeable acidity and an increase in ECEC in the two upper soil layers. By the end of the monitoring period, overall net Mg retention in the 0-15 cm columns increased in the order kieserite < CaCO3 + kieserite << dolomite with respectively 20, 35 and 85% of cumulated inputs remaining in the columns. The corresponding net Ca retention amounted to 82 and 96% of cumulated inputs for the CaCO3 + kieserite and dolomite treatments, respectively. Results from this study complement those obtained in the field by clearly demonstrating the mechanisms involved in the downward movement of some fertilizers commonly used to increase the base saturation of acid forest soils.

Changes in soil physical properties of four different fields during and after upland reclamation that involved grading

Abstract In four fields reclaimed with grading (Shari: coarse Stratic Regosolic Andosols; Kyowa: fine Brown Andosols; Hokuryu: Acid Brown Forest soils with medium texture; and Toma: Acid Brown Forest soils with Dark Epipedon and medium texture), changes in the physico-chemical and structural properties of soil strata subjected to surface layer handling (hereafter referred to as “surface layer handled soil strata” (SLHS)) were investigated during and after reclamation. 1. SLHS were estimated to be derived mainly from the A and B horizons of each pre-reclaimed forest soil except for the Shari field where buried horizons were also treated in the same way as the surface soil layer.2. During surface layer handling (SLH), SLHS were structurally degraded in all the fields.3. During SLH, the compaction (increase in bulk density and decrease in coarse-size pore volume (CP: from 0 to -6.23 kPa) and easily-available water-holding pore volume (EAW: from -6.23 to -100 kPa)) of SLHS proceeded except for coarse textured soils (Shari).4. In the Kyowa and Toma fields, bulk density of SLHS decreased, CP increased after a single plowing and harrowing, unlike EAW, even when SLH was performed at a low soil moisture level. In both fields, the recovery of EAW was smaller than that of CP during the several years after SLH. Countermeasures for the recovery of EAW should be investigated further.5. In the Hokuryu field where SLHS contained swelling clay and the soil moisture was estimated to have been high when SLH was performed, bulk density, CP, and EAW of the upper SLHS did not recover appreciably during the 8-year period after SLH. Shrinkage with dehydration proceeded in the lower SLHS during this period. Reclamation procedures should thus be conducted when the soil moisture is low.6. The effects of subsoiling conducted after SLH differed with the soil types and soil moisture levels.