Changes in the content and composition of humus in the sandy loamy soddy-podzolic soil in a long-term liming experiment

The effect of liming on organic matter in sandy loamy soddy-podzolic soil was studied. The study was performed on samples taken from the 50-year-long experiment established by Prof. Kornilov in 1957. It was shown that liming had almost no effect on the total humus content in the soil. The humus composition was studied using two fractionation methods of the humus substances by the Ponomareva-Plotnikova procedure. The regrouping of the humus fractions occurred due to the changes in the mobility of soil mineral components, which involved a regular increase in the content of the Ca-bound fraction of humic acids (HA-2) at the expense of the HA-1 fraction bound to the mobile forms of R₂O₃ reliable at the lime rates equivalent to the total acidity and higher. The levels of the stabilization of the different HA fractions were considered, as well as the stability of the changes in the humus composition during 50 years.     

Effect of metal contamination on microbial enzymatic activity in soil

Anthropogenic metal contamination is a pervasive problem in many urban or industrial areas. The interaction of metals with native soil communities is an important area of research as scientists strive to understand effects of long-term metal contamination on soil properties. Measurements of free soil enzyme activities can serve as useful indicators of microbial metabolic potential. The goals of this study are to determine extracellular soil enzymatic activities with respect to corresponding metal concentrations within a site of long-term contamination. These data are examined to understand relationships between extracellular soil enzyme activities and persistent metal loads in situ. Here we present such results from a rare research opportunity at an un-remediated, urban brownfield in Jersey City, NJ, USA. The soils of the site developed over the last 150 years through the dumping of urban fill from New York City as well as industrial rail use. The site was abandoned and fenced in the late 1960s, and within it, there is a mapped gradient of metal concentration in the soils, including As, Pb, Cr, Cu, Zn, and V. We measured soil enzymatic potential (alkaline phosphatase, cellobiohydrolase, and l-leucine-amino-peptidase) across four plots within the site and at an uncontaminated reference site that is of the same successional age and geographic influence. We found the highest enzymatic activities for all three activities measured at the site with the greatest soil metal loads and a particularly strong relationship among enzyme activity and the metals V and Cr. Our results differ from many experimental studies that show decreased soil enzyme activity in soils experimentally treated with metals. The results may indicate the effects of long-term adaptation of soil communities within these metal contaminated soils.     

Structural and functional features of microbial communities in a soddy-podzolic soil under self-remediation conditions

The microbial component is one of the key factors responsible for soil fertility and soil quality. The sensitivities of some structural and functional parameters of soil microbial communities in soddy-podzolic soils under long-term self-remediation conditions were compared. The suitability of the parameters studied for quantifying the resilience of soil biota to agricultural intervention was studied.     

The effect of liming on the complex of soil microorganisms and the humus status of a soddy-podzolic soil in a long-term experiment

The influence of the prolonged application of different lime doses (including elevated ones) on the complex of soil microorganisms and the humus status of a sandy loamy soddy-podzolic soil was studied in a long-term field experiment. The content of labile humus substances extracted with 0.1 M KCl (pH 4.3–4.4) and that of organic matter extracted with hot water became reduced. When liming, the number of all the bacterial groups significantly increased. On the contrary, the number of micromycetes decreased by 3.5–4.2 times. However, the liming did not cause any changes in the complex of soil microorganisms and the content of organic matter, thus indicating the normal functioning of the whole soil ecosystem.     

重金属对土壤微生物酶活性的影响

本文通过含有不同浓度的铜、铅、砷、镉 4种重金属的大豆、小麦盆栽试验 ,采用气相色谱方法测定土壤微生物酶活性 .结果表明 :低浓度的重金属能够提高固氮酶和反硝化酶的活性 ,而高浓度的重金属对上述二种酶有强烈的抑制作用     

Dynamics of the dispersity of model soddy-podzolic soils in a long-term lysimetric experiment

Changes in the particle-size composition and specific surface area were considered for soddy-podzolic soils in large lysimeters of the Soil Research Station of Moscow State University, which simulated anthropogenically modified soils with different sequences of genetic horizons in a long-term (1961–2002) experiment. Changes were detected in the degree of dispersion of the soil horizons occurring under conditions inadequate for their genesis: a decrease in the clay content by 7% and in the external specific surface area from 28.9 to 7.4% in the illuvial horizon placed on the surface and the accumulation of colloidal mineral fractions in the Ap horizon buried at a depth of 80–100 cm. The degree of change depended on the occurrence depth of the buried horizons and increased with approaching the surface. The changes in the dispersity of the model soddypodzolic soils in the lysimetric experiment were primarily due to the translocation of the fine fractions with vertical water flows. The long-term experiment carried out under completely controlled conditions showed that, at the initial functioning stages of the soils with anthropogenically modified profiles, this process was well detectable and significant for the monitoring studies.     

Influence of xenobiotics on the microbiological and agrochemical parameters of soddy-podzolic soil

We studied the influence of various chemical compounds, i.e., azobenzene (an insecticide and acaricide), nitrification inhibitors (DCD, dicyandiamide and DMPP, and 3,4-dimetylpyrazolphosphate), and inhibitors of urease activity (HQ-hydroquinone), on the agrochemical and microbiological parameters of a soddy-podzolic soil. It is proved that these xenobiotics are able to influence the agrochemical parameters (the pH and the content of NO₃⁻ and NH₄⁺, the microbial activity (the basal respiration, the microbial mass carbon, and the microbial quotient), and the number of bacteria of different physiological groups in soddypodzolic soil. The influence of the xenobiotics was preserved for some time, which testified to their persistence in the soil. Upon cultivating the soil microorganisms in different media, the growth of the heterotrophic bacteria was inhibited, the radial growth velocity was slowed down, and the sporogenesis of the micromycetes was retarded. The toxic effect of the xenobiotics was higher with their increasing concentrations.     

The effect of soil water content and microbial activity on restoring the structure of a Vertisol

Soils with high clay content are susceptible to structural damage, if they are intensively cultivated. The structure of soils of the Vertisol group has the tendency to restore as a result of wetting and drying. Samples of a remoulded clayey soil were exposed to seven successive wetting/drying (w/d) cycles, in order to study the change of some structural features of the newly formed aggregates. To assess the effect of soil water content and microbial activity, two different matric water potential ranges were used under sterile and non-sterile conditions.

Aggregate size distribution depended on both the water potential range and microbial activity and approached to a steady state with increasing cycle number. The water stability of the 2–1 mm aggregates was affected by the activity of soil micro-organisms under wet conditions and by forces of mechanical nature when the soil was reaching dryness. All cases resulted in aggregates of reduced water stability with respect to the natural aggregates. The <50 μm aggregated particles initially preserved stability, but after a number of w/d cycles they collapsed at a rate, depending mainly on the water potential range.     

Influence of climate factors on soil heavy metal content in Slovenia

Purpose

In spite of equal lithology, the local climate can affect soils’ geochemical characteristics. We investigated the dependence of heavy metal content on climatic factors according to a hierarchical nested analysis of variance design (ANOVA).

Materials and methods

We examined the heavy metal content in soils developed on the Upper Triassic dolomite at six locations situated at increasing distances from the Adriatic Sea towards inland. We tested the influence of the locations’ position, i.e. climate, vegetation cover, small-scale variability and analytical error. Co, Cr, Cu, Ni, Pb and Zn contents were determined by emission spectrometry.

Results and discussion

An initial increase in annual precipitation towards inland is followed by a steady decrease. Very high small-scale variability prevented statistically significant differences from being established at the location level due to the high variance components exhibited. However, the simpler one-way and non-parametric varieties of ANOVA confirmed significant differences in Co, Cr and Ni among locations. The differences are more pronounced in grassland soils where the Cu and Pb contents also differ between locations. There is a positive correlation among annual precipitation, Co, Cr and Ni, and it seems that the prevailing winds can also influence their content in soils.

Conclusions

The Co, Cr, Cu and Ni values are readily the highest in those locations with the greatest precipitation, possibly due to their resistance to leaching. The soils could be additionally enriched by an eolian contribution from the SW located outcropping flysch rocks. The established variability could be due to somewhat different dolomite composition. The reasons for the observed geochemical variability are complex and only partly due to climate.

     

Heavy metal content in soil and plants from a pyrite mining area in Southwest Spain

Abstract

Mineral content was measured in soils and leaves of eight woody plant species growing in a pyrite mining area in southwest Spain. The concentration of copper, manganese, zinc and aluminium in leaf tissues varied between species. The results are related to contrasting mechanisms, “excluders”; vs. “accumulators,”; of plant response to heavy metal stress. The lasting effects of pyrite melting activities on surrounding soil and plants were evaluated and compared with heavy metal values in a nearby forest.     

Influence of soil water content and soil amendments on trace metal release and seedling growth in serpentine soil

Journal of Soils and Sediments - This study was conducted to evaluate the synergistic effects of organic amendments and soil water status on trace metal release from serpentine soil. Two organic...     

Influence of microbial activity and soil moisture on herbicide immobilization in soils

Mobility, extractability, and disappearance of the herbicides diuron, terbuthylazine, metolachlor, and pendimethalin were examined in incubation experiments with two topsoil samples of different natural microbial activity and after sterilization. Soil moisture was held constant at 10, 40, and 60 % WHC. In other variants, the soil water content was changed during the incubation. The four herbicides reveal a fairly different extent of microbial and chemical degradation and immobilization. The herbicide mobility – expressed by coefficients of partition between adsorbed and dissolved herbicide amounts – decreases at a lower rate and extent, when the microbial activity is low or the soil is sterile. With increasing initial soil moisture, also herbicide mobility and extractability increase; but in the course of time, abiotic immobilization occurs to a higher extent. When soil moisture changes during the incubation, formerly non‐extractable herbicide fractions (up to 40 % of the applied amounts) become extractable. Kinetics of herbicide immobilization follow an empirical sigmoidal function, which describes three periods of immobilization. The three‐period shape of the curve and its possible reasons are discussed for the data of the incubation experiments as well as for the results of a long‐term field trial with diuron.     

Influence of selenium on oxidoreductive enzymes activity in soil and in plants

The aim of this greenhouse experiment was the assessment of the influence of H₂SeO₃ at soil concentrations of 0.05, 0.15 and 0.45 mmol kg⁻¹, on the activity of selected oxidoreductive enzymes in wheat (Triticum aestivum). The wheat plants were grown in 2 dm³ pots filled with dust-silt black soil of pH 7.7. Applied H₂SeO₃ caused activation of plant nitrate reductase at all concentrations, but activation of plant polyphenol oxidase at only two lower concentrations. The highest concentration caused inhibition of polyphenol oxidase and peroxidase. Plant catalase activity decreased under the influence of 0.15 and 0.45 mmol kg⁻¹ concentration. After the final analysis Se was quantified in plants and soil. The amounts in plants were: control (unamended soil) 1.95 mg kg⁻¹; I dose (0.05 mmol kg⁻¹) 18.27 mg kg⁻¹; II dose (0.15 mmol kg⁻¹) 33.20 mg kg⁻¹ and III dose (0.45 mmol kg⁻¹) 38.37 mg kg⁻¹, in soil: 0.265 mg kg⁻¹; 3.61 mg kg⁻¹; 10.53 mg kg⁻¹; 30.53 mg kg⁻¹; respectively. Simultaneously, a laboratory experiment was performed, where the activity of soil catalase and peroxidase were tested after 1, 3, 7, 14, 28, 56, and 112 days after Se treatment. Peroxidase activity in soil decreased with increasing Se content, over the whole experiment. The lowest dose of Se caused activation a significant 10% increase in catalase activity, but the influence of others doses was unclear.     

Physical properties of soddy-podzolic soils in a long-term field experiment

The main physical properties of soddy-podzolic soils in a long-term field experiment have been studied. It is shown that their changes under the impact of a century-long application of lime, fertilizers, and manure have been relatively small. Reliable differences in the parameters of approximation of the dependence of penetration resistance on the soil water content in the variant with regular application of organic fertilizers have been revealed. This attests to stronger interparticle bonds (within the studied moisture range) in this variant. Interparticle bonds in the control variant and in the variant with lime application tend to increase with a decrease in the soil water content more significantly than those in other experimental variants. This may be due to the coarser texture of the soil in the control variant and to the aggregation of soil particles under the impact of lime in the variant with lime application.     

Influence of polychlorinated biphenyls on microbial biomass and its activity in grassland soil

Microbial biomass content, soil respiration and biomass specific respiration rate were measured in two parts of an area polluted by a municipal waste incinerator [polychlorinated biphenyls (PCBs) from combustion processes]. The soils in the studied parts differed significantly only in their levels of PCBs. The concentration of PCBs found in a control plot (4.4 ng g^-1 soil) can be regarded as a background value while the polluted plot contained an increased amount of PCBs (14.0 ng g^-1 soil). A significantly lower microbial biomass (decreased by 23%, based on the chloroform-fumigation extraction technique) and a lower specific respiration rate (decreased by 14%) were observed in the polluted plot in comparison with the control plot at the end of experimental period (1992–1994). Furthermore, a lower ability of microorganisms in the polluted plot to convert available C_org into new biomass was found in laboratory incubations with glucose-amended samples.     

Influence of the ionic strength of nutrient solutions and tropical acid soil solutions on aluminum activity

Aluminum (Al) activity was determined in nutrient solutions and in acid soil solutions. Aluminum concentrations in the solutions ranged from 7.4 μM to 370.3 μM giving values of ionic strength of nutrient solutions higher than the values of acid soil solutions. The increase of ionic strength values was due to the increase of Al concentrations. The values of Al activities of 20 uM in the acid soil solutions were noticed when Al concentrations were lower than 70 μM. On the other hand, these values of Al activities in nutrient solutions were noticed only when the Al concentrations were higher than 70 μM. This study demonstrates why it is important to use higher Al concentrations in nutrient solutions to obtain Al toxic effects.     

Influence of agricultural practices on soil microbial activity measured by microcalorimetry

To investigate the influence of different agricultural practices and vegetations on soil microbial activity and diversity, soil samples from different habitats were studied with their microbial activities measured by the microcalorimetric technique. Seven soil samples were collected in Wuhan, China from different locations with primary and regeneration forest, nursery and crop land, and uncultivated land. The number of microorganisms in soils was measured by viable count, and some physicochemical parameters were determined. Power–time curves were recorded for soil samples supplemented with glucose and ammonium sulphate, and the total heat changes of the microbial growth reaction, Q_total (Jg⁻¹) and the microbial growth rate constant, k (min⁻¹) were calculated from the curves. All power–time curves presented typical changes of microbial activity. The curves of soil samples could be divided into two groups differing in agricultural practices and vegetations. The same grouping could also be reached according to the values of peak time (t_max). The most soil samples showed a higher correlation between the values of k and the counted bacterial numbers. The Q_total correlated well with vegetation abundance and probably with microbial diversity. In conclusion, microbial activity of the soil samples determined by microcalorimetry reflected differences in soil vegetation and agricultural management.     

The effect of oil contamination on bacteria in a soddy-podzolic soil

The effect of oil contamination on bacteria in a soddy-podzolic soil was studied. Oil was introduced into the soil 8, 11, and 17 years ago. It was found that oil contamination has exerted long-term negative effects on the number and biomass of the soil bacteria. The deficiency of available phosphorus was one of the major negative factors affecting these parameters in the old-contaminated soils. The application of Na₂HPO₄ to the contaminated soils eliminated this negative effect. The effect of oil contamination on the taxonomic diversity and structure of the bacterial community in the studied soil was determined with the help of denaturating gradient gel electrophoresis.     

Structure and function of the soil microbial community in a long-term fertilizer experiment

The effect of organic and inorganic fertiliser amendments is often studied shortly after addition of a single dose to the soil but less is known about the long-term effects of amendments. We conducted a study to determine the effects of long-term addition of organic and inorganic fertiliser amendments at low rates on soil chemical and biological properties. Surface soil samples were taken from an experimental field site near Cologne, Germany in summer 2000. At this site, five different treatments were established in 1969: mineral fertiliser (NPK), crop residues removed (mineral only); mineral fertiliser with crop residues; manure 5.2 t ha⁻¹ yr⁻¹; sewage sludge 7.6 t ha⁻¹ yr⁻¹ or straw 4.0 t ha⁻¹ yr⁻¹ with 10 kg N as CaCN₂ t straw⁻¹. The organic amendments increased the C_org content of the soil but had no significant effect on the dissolved organic C (DOC) content. The C/N ratio was highest in the straw treatment and lowest in the mineral only treatment. Of the enzymes studied, only protease activity was affected by the different amendments. It was highest after sewage amendment and lowest in the mineral only treatment. The ratios of Gram+ to Gram− bacteria and of bacteria to fungi, as determined by signature phospholipid fatty acids, were higher in the organic treatments than in the inorganic treatments. The community structure of bacteria and eukaryotic microorganisms was assessed by denaturing gradient gel electrophoresis (DGGE) and redundancy discriminate analyses of the DGGE banding patterns. While the bacterial community structure was affected by the treatments this was not the case for the eukaryotes. Bacterial and eukaryotic community structures were significantly affected by C_org content and C/N ratio.     

Structure and function of the soil microbial community in microhabitats of a heavy metal polluted soil

 Particle-size fractionation of a heavy metal polluted soil was performed to study the influence of environmental pollution on microbial community structure, microbial biomass, microbial residues and enzyme activities in microhabitats of a Calcaric Phaeocem. In 1987, the soil was experimentally contaminated with four heavy metal loads: (1) uncontaminated controls; (2) light (300 ppm Zn, 100 ppm Cu, 50 ppm Ni, 50 ppm V and 3 ppm Cd); (3) medium; and (4) heavy pollution (two- and threefold the light load, respectively). After 10 years of exposure, the highest concentrations of microbial ninhydrin-reactive nitrogen were found in the clay (2–0.1 μm) and silt fractions (63–2 μm), and the lowest were found in the coarse sand fraction (2,000–250 μm). The phospholipid fatty acid analyses (PLFA) and denaturing gradient gel electrophoresis (DGGE) separation of 16S rRNA gene fragments revealed that the microbial biomass within the clay fraction was predominantly due to soil bacteria. In contrast, a high percentage of fungal-derived PLFA 18 : 2ω6 was found in the coarse sand fraction. Bacterial residues such as muramic acid accumulated in the finer fractions in relation to fungal residues. The fractions also differed with respect to substrate utilization: Urease was located mainly in the <2 μm fraction, alkaline phosphatase and arylsulfatase in the 2–63 μm fraction, and xylanase activity was equally distributed in all fractions. Heavy metal pollution significantly decreased the concentration of ninhydrin-reactive nitrogen of soil microorganisms in the silt and clay fraction and thus in the bulk soil. Soil enzyme activity was reduced significantly in all fractions subjected to heavy metal pollution in the order arylsulfatase >phosphatase >urease >xylanase. Heavy metal pollution did not markedly change the similarity pattern of the DGGE profiles and amino sugar concentrations. Therefore, microbial biomass and enzyme activities seem to be more sensitive than 16S rRNA gene fragments and microbial amino-sugar-N to heavy metal treatment. Received: 21 January 2000