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1.
This study aimed to elucidate the response of diversity and activity of soil invertebrates to elevated soil metal concentrations that were a result of sewage sludge application. Field sampling of soil invertebrates was carried out from 2002 to 2004 at an experimental site established in 1982 to test the effects on crop production of metal contamination from sewage sludge applications with elevated concentrations of zinc (Zn), copper (Cu) and nickel (Ni) with certain treatments exceeding the current UK statutory limits for the safe use of sludge on land. At metal concentrations within the limits, none of the invertebrates sampled showed adverse effects on their abundance or overall community diversity (from Shannon–Weiner index). At concentrations above the limits, individual taxa showed sensitivity to different metals, but overall diversity was not affected. Earthworm abundance was significantly reduced at total Cu concentrations at and above 176 mg kg?1, while nematode and enchytraeid abundances were sensitive to Cu and high Zn concentrations. Correspondingly, litter decomposition was lower in Zn and Cu treatments although there was no direct relationship between decomposition and soil invertebrate abundance or diversity. Such enduring changes in both soil biodiversity and biological activity around the current UK regulatory limits warrant further investigation to determine whether they indicate detrimental damage to soil functioning over the long‐term.  相似文献   

2.
A method was proposed for studying the degradation of soil aggregates in time from the absorption of 137Cs β-radiation by a soil sample. The method is based on the difference in the recorded β radiation intensities depending on the distribution of 137Cs between the surface of the aggregates and the nonaggregated soil material. At the localization of the radionuclide on the surface of the soil aggregates, the counting rate will significantly exceed that for the samples containing a similar amount of the radionuclide uniformly distributed throughout the soil volume. This effect is due to the insignificant range of the mild β radiation in the soil (less than 1 mm depending on the radiation energy). Relatively clear calibration graphs under the selected conditions of the radiometric measurements were obtained for the aggregates whose sizes were in the range of 3–10 mm. Under natural conditions, the 7- to 10-mm aggregates of a dark gray clay loamy soil under a forest belt decomposed by 50–65% at a depth of 10 cm and by 23–32% at a depth of 30 cm. The more intense degradation of the soil aggregates of the same size was observed under the conditions of a pot experiment.  相似文献   

3.
Abstract

This study was to determine the effect of soil amendments on the fractionation of selenium (Se) using incubation experiments under simulated upland and flooded conditions. The treatments were as follows: 1) control [soil + sodium selenite (Na2SeO3) (1 mg Se kg‐1)]; 2) control + calcium carbonate (CaCO3) (5 g kg‐1); 3) control + alfalfa (40 g kg‐1); and 4) control + CaCO3 (5 g kg‐1) + alfalfa (40 g kg‐1). After a 90‐day incubation, soil was sampled and fractionated into five fractions: 1) potassium sulfate (K2SO4)‐soluble fraction (available to plants); 2) potassium dihydrogen phosphate (KH2PO4)‐exchangeable fraction (potentially available); 3) ammonium hydroxide (NH3H2O)‐soluble fraction (potentially available); 4) hydrochloric acid (HCl)‐extractable fraction (unavailable); and 5) residual fraction (unavailable). Compared with the control, CaCO3 increased the K2SO4 fraction at the expense of the NH3H2O fraction. Alfalfa increased both the K2SO4 and residual fractions but reduced the KH2PO4 and NH3H2O fractions. The CaCO3‐alfalfa treatment had a similar effect to the alfalfa treatment alone. The comparison between the upland and flooded conditions showed that the flooded condition generally increased the residual fraction and decreased the potentially‐available fractions. In general, CaCO3 was a better amendment because it not only increased the available fraction but also maintained the potentially available fractions at a high level. The application of Na2SeO3 and use of appropriate soil amendments can improve Se availability in soil.  相似文献   

4.
Unique experiments performed since the 1950s at the Arshan’-Zel’men Experimental Station have formed the basis for afforestation in the dry steppe and semidesert zone without irrigation on the salt-affected soils of solonetzic soil complexes of the Ergeni Upland. Ameliorative measures favored the accumulation of productive moisture in the upper 2-m-thick soil layer, which ensured the growth of trees and the partial leaching of soluble salts to a depth of 1–1.4 m. However, no complete desalinization of the soil profiles took place. The degree of removal of exchangeable sodium from the exchange complex (soil dealkalization) was smaller. The monitoring of changes in the salt status of the soils upon agroforest reclamation was performed until the early 1980s. Our investigations of 2005–2006 showed that the soil amelioration is still in progress: the salt maximum in the profile of the solonetzes descended to a depth of 2.2 m, and the exchangeable sodium was lost from the plow layer (0–40 cm). Plowed soils between forest shelterbelts were also subjected to desalinization and dealkalization of their soil profile, though less intensely than those under the shelterbelts.  相似文献   

5.
A methodological approach to the physically sound mathematical simulation of the hydrothermal regime for a complex soil cover on an agricultural field scale was proposed. To realize the approach, it is necessary (1) to restore the hydrothermal regime of two contrasting soils using a physically sound mathematical model on the basis of the experimental thermophysical and hydrophysical characteristics, (2) to adapt and optimize the model using the available experimental regime data, (3) to determine the hydrophysical and thermophysical properties for the entire plot under study using pedotransfer functions, and (4) to restore the hydrothermal regime of the entire soil plot using a mathematical model and the meteorological data for a specific time period. The proposed procedure allows simulating the hydrothermal regime of an agrogray soil complex in the Vladimir Opol??e region with a normalized standard error of about 8%. The analysis of the hydrothermal regime for the soil cover of the studied plot calculated from the meteorological data for the period from May to August of 2009 showed that the lower temperature values were confined to the areas of the agrogray soils with the second humus horizon: their average temperature was lower than the temperature of the agrogray soils by 0.44, 0.93, and 1.32°C at depths of 20, 40, and 70 cm, respectively, and the differences between their sums of the active temperatures for the considered period of 2009 reached 89 and 74°C at depths of 20 and 40 cm, respectively.  相似文献   

6.
A method is described for the rapid and simple assay of soil β-glucosidase activity. It involves colorimetric estimation of ρ-nitrophenol released by β-glucosidase activity when soil is incubated in McIlvaine buffer (pH 4.8) with ρnitrophenyl βd-glucoside and toluene at 30°C for 1 hr. The method has been applied to three different soils. The range of β-glucosidase activity in cultivated soils was from 10.1 to 15.2 mµ mole per min per gram of dried soil. Km value for ρ-nitrophenyl β-d-glucoside was 3.3 × 10-4 M. Optimum pH was 4.8.  相似文献   

7.
<正>Dear Editor,Globally, approximately two billion people suffer from micronutrient deficiencies(Tulchinsky, 2010; Myers et al.,2014).Soil micronutrient availability is of great importance for the evaluation of soil fertility and the determination of appropriate measures for improving crop quality and human health.The diethylenetriamine-penta-acetic(DTPA)  相似文献   

8.
The structure of soil organic matter (SOM) and humic substances (HS) has been discussed from different viewpoints including molecular conformation, molecular aggregation, macromolecularity, supramolecular characteristics, domain mobility, and many others. Until now, the individual models appear partly contradictory, although each viewpoint provides important information on the structural and functional properties of SOM. This is most probably due to the huge heterogeneity of SOM. Therefore, the question: “How can molecular modeling help to further understand structure and functioning of soil organic matter?” needs to be addressed with care. This contribution reviews and discusses the potential of important molecular modeling approaches currently applied in soil organic matter science.Computer models are useful in giving a visualization of the general structure and of the possible effects on soil chemistry and soil physics. Computational chemistry in this context aims to estimate a lowest energy conformation for a molecule or an assembly of molecules specified by the programmer. On the basis of the calculated conformation, physicochemical characteristics like surface area, polarity and other can be estimated and information on the stability of molecular assemblies can be derived. The significance of the obtained conformation and physicochemical information strongly depends on the initial hypothesis of the molecular structure of each involved molecule. Recent computer models have been developed on the base of computer assisted structure elucidation (CASE). In this procedure, all possible isomers or a statistically representative set of isomers consistent with the experimental input data are processed.Further interesting fields of computational chemistry in soil research follow a different conception, where specific processes of interest are elucidated with the help of computational models which simplify the humic molecules with respect to the individual modeling problem. This way helps to understand the relevance of principal processes expected to occur in soil. In this context, complexes of Al with organic acids, clay mineral sorption sites, interactions of pesticides with organic functional groups or organic soil constituents as well as cross-linking of molecule segments by water molecules were modeled in targeted process-orientated models. The act of simplification is the crucial process in these kinds of models, and if the models are based on good conceptions, they allow to learn about potential SOM functioning. The transfer to more complex situations, however, needs special care and the predictive character of these models needs to be judged with care. Still, any computer model is only as good as its initial hypothesis.  相似文献   

9.
Effect of vegetation changes on soil erosion on the loess plateau   总被引：48，自引：0，他引：48  
ZHENG Fen-Li 《土壤圈》2006,16(4):420-427
Vegetation is one of the key factors affecting soil erosion on the Loess Plateau. The effects of vegetation destruction and vegetation restoration on soil erosion were quantified using data from long-term field runoff plots established on the eastern slope of the Ziwuling secondary forest region, China and a field survey. The results showed that before the secondary vegetation restoration period （before about 1866-1872）, soil erosion in the Ziwuling region of the Loess Plateau was similar to the current erosion conditions in neighboring regions, where the soil erosion rate now is 8 000 to 10 000 t km^-2 year^-1. After the secondary vegetation restoration, soil erosion was very low; influences of rainfall and slope gradient on soil erosion were small; the vegetation effect on soil erosion was predominant; shallow gully and gully erosion ceased; and sediment deposition occurred in shallow gully and gully channels. In modern times when human activities destroyed secondary forests, soil erosion increased markedly, and erosion rates in the deforested lands reached 10 000 to 24000 t km^-2 year^-1, which was 797 to 1682 times greater than those in the forested land prior to deforestation. Rainfall intensity and landform greatly affected the soil erosion process after deforestation. These results showed that accelerated erosion caused by vegetation destruction played a key role in soil degradation and eco-environmental deterioration in deforested regions.  相似文献   

10.
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11.
Abstract

An experiment was conducted to determine if time‐domain reflectometry (TDR) could be used to measure the water content at different depths in the O‐to‐75 cm soil layer. Probes of three wires (1/8 inch diameter and 30 cm exposed length) were installed in field plots differing in current crop‐fertilization history. Measurements of volumetric water content using bulk density and gravimetric water content were made to calibrate the TDR method. Comparison of water contents determined by TDR with those from gravimetric samples showed that there is a linear relationship (small offset but same slope) of water content with depth, indicating that there is little difference in volumetric water content from the 0 to 75 depth. However, the TDR method gives consistently lower water content values as compared with values obtained by gravimetric determination. Continuous measurements of profile soil water content with TDR in wet and dry periods during the year indicated that the mayor differences in volumetric water content correspond to the first 30 cm depth.  相似文献   

12.
Three soil classification systems—the World Reference Base for Soil Resources (WRB), Soil Taxonomy, and the recent Russian system—were used for the identification of 17 soil profiles in southwestern Poland; all the systems put emphasis on the soil properties as diagnostic criteria. Different soils developed on glaciofluvial plains, loessic uplands, and in the Sudetes Mountains were classified. The best correlation between the classification decisions in the different systems was obtained for the most widespread soils owing to the similarity of the diagnostic criteria, which were essentially close although not coinciding. The most prominent divergence between the systems in both the names and the taxonomic categories of the soils was found for the polygenetic soils and for the soils developing from the lithologically discontinuous parent materials. It was also found that the diagnostic elements differ in terms of their taxonomic importance among the classification systems.  相似文献   

13.

Purpose

Soil organic matter (SOM) plays a vital role in controlling metal bioavailability. However, the relationship between SOM and its fractions, including water-soluble substances (WSS), fulvic acid (FA), humic acid (HA), and soil microbial biomass (SMB), to metal bioavailability in plants has not been thoroughly investigated. This study examined the compositional change of SOM after tea polyphenols (TPs) were added to the soil and its correlation with Pb bioavailability.

Materials and methods

Ultisol samples were collected from Fuyang, spiked with two levels (0 and 300 mg kg?1 DW) of Pb, and aged for 30 days. Four uniform seedlings were transplanted to each plastic pot, which were filled with 3 kg of air-dried soil. After successful transplantation, three levels (0, 300, and 600 mg kg?1 DW) of TPs were amended as irrigation solution for the pots. The Pb concentrations in different tissues of the tea plants were determined after 6 months. SOM, WSS, FA, HA, and SMB were extracted and quantified using a Multi N/C Total Organic Carbon Analyser.

Results and discussion

Adding TPs to Pb-polluted soils alleviated Pb toxicity to microorganisms and increased SMB and the rhizosphere effect. The rhizosphere SOM was lower than bulk SOM in Pb-unspiked soils, while the opposite results were observed in Pb-spiked soils. A similar inconsistency for HA in the rhizosphere and bulk soil between Pb-unspiked and Pb-spiked soils might explain the difference in SOM. FA increased with the addition of TPs in both the rhizosphere and bulk soils, which might be the result of TP transformation. Positive correlations are present between the compositions of rhizosphere SOM and Pb in different tissues of the tea plant. SMB correlated negatively with Pb in young leaves and stems. Compared to rhizosphere soil, SOM components in bulk soil were less strongly correlated with Pb in tea plants.

Conclusions

Addition of TPs to soil changes the components of SOM and Pb bioavailability. SOM and its fractions, including WSS, FA, HA, and SMB, show a close relationship to Pb in different tissues of the tea plants.  相似文献   

14.
The scaling up of processes in the plant–soil–microbe system represents one of the greatest challenges facing environmental scientists and yet is essential for sustainable land management worldwide. The latter encompasses, for example, the mitigation of and adaptation to anthropogenic climate change, the bioremediation of industrially contaminated sites, catchment management of human pathogens such as Escherichia coli O157 and integrated crop management on the farm. Scaling up is also essential for the regional and global biogeochemical modelling that will inform policy-makers of the critical environmental factors driving climate change. Despite increasing understanding of the links between gene expression and process on a microscale, there is still much progress to be made when relating this to processes at the macroscale. In this paper, we explore the challenges this poses and examine key case studies of successful up-scaling.
Dominic StandingEmail:
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15.
The work considers the accumulation and redistribution of 137Cs and 60Co among the components of natural ecosystems (soils, bottom sediments, surface waters, and plants of different ecological groups (mesophytes, hygrophytes, hydrophytes, and hydathophytes)) within the impact zone of the Novovoronezh Nuclear Power Plant. It is shown that the current radioecological situation on this territory is satisfactory. Each of the studied parameters complies with the radiation safety standards.  相似文献   

16.
Can root exudate components influence the availability of pyrene in soil?   总被引：1，自引：0，他引：1  

Purpose

Little information is currently available regarding the influence of different root exudate components (RECs) on the availability of persistent organic pollutants in the soil environment. In this study, we investigated the impacts of different RECs including organic acids, amino acids, and fructose on the availability of pyrene as a representative polycyclic aromatic hydrocarbon (PAH) in soils.

Materials and methods

Citric acid, oxalic acid, malic acid, serine, alanine, and fructose were used in the experiments as representative RECs. Pyrene-spiked soils (TypicPaleudalfs) with present RECs were incubated for 30 days, and the available fraction of pyrene was determined using n-butanol extraction procedure.

Results and discussion

The amount of n-butanol-extractable pyrene in soil increased with the addition of tested RECs and increased when REC concentrations are enhanced within the range of 0–21 g kg?1. The extractability of pyrene in soil with REC treatments and the enhancement ratio (r, %) of the extractable pyrene in soil by the addition of RECs after a 30-day incubation decreased in the following order: organic acids (oxalic acid ≥ citric acid > malic acid) > amino acid (alanine > serine) > fructose. This decrease was observed irrespective of soil sterilization, although the concentrations of extractable pyrene were lower in non-sterilized soils compared to sterilized soils. The concentrations of metal cations and dissolved organic matter (DOM) in solution increased when organic acids were added.

Conclusions

The tested RECs at concentrations of 0–21 g kg?1 clearly enhanced the availability of pyrene in soils, and larger amounts of RECs resulted in higher pyrene availabilities in the tested soils. Microbial biodegradation diminished the amount of available pyrene irrespective of the presence of RECs. The mechanism of REC-influenced availability of pyrene in soil may be related to the metal dissolution and release of DOM from soil solids. The results of this study will be useful in assessing PAH-related risks to human health and the environment and will be instructive in food safety and remediation strategies at contaminated sites.  相似文献   

17.
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18.
The increasing demand for biomass for food, animal feed, fibre and bioenergy requires optimization of soil productivity, while at the same time, protecting other soil functions such as nutrient cycling and buffering, carbon storage, habitat for biological activity and water filter and storage. Therefore, one of the main challenges for sustainable agriculture is to produce high yields while maintaining all the other soil functions. Mechanistic simulation models are an essential tool to fully understand and predict the complex interactions between physical, biological and chemical processes of soils that generate those functions. We developed a soil model to simulate the impact of various agricultural management options and climate change on soil functions by integrating the relevant processes mechanistically and in a systemic way. As a special feature, we include the dynamics of soil structure induced by tillage and biological activity, which is especially relevant in arable soils. The model operates on a 1D soil profile consisting of a number of discrete layers with dynamic thickness. We demonstrate the model performance by simulating crop growth, root growth, nutrient and water uptake, nitrogen cycling, soil organic matter turnover, microbial activity, water distribution and soil structure dynamics in a long-term field experiment including different crops and different types and levels of fertilization. The model is able to capture essential features that are measured regularly including crop yield, soil organic carbon, and soil nitrogen. In this way, the plausibility of the implemented processes and their interactions is confirmed. Furthermore, we present the results of explorative simulations comparing scenarios with and without tillage events to analyse the effect of soil structure on soil functions. Since the model is process-based, we are confident that the model can also be used to predict quantities that have not been measured or to estimate the effect of management measures and climate states not yet been observed. The model thus has the potential to predict the site-specific impact of management decisions on soil functions, which is of great importance for the development of a sustainable agriculture that is currently also on the agenda of the ‘Green Deal’ at the European level.  相似文献   

19.
Abstract

A representative grassland soil of the lowland areas of the Flooding Pampa (Argentina) was sampled to study the dynamics of the non‐exchangeable ammonium under waterlogging conditions. Most of the external factors determining fixed ammonium release and fixation were considered. There was no net release of ammonium from the clay fixing‐sites to the soil solution, when this soil was flooded under laboratory conditions. We conclude that the non‐exchangeable ammonium fraction in this soil is very stable and with little importance as a nitrogen source for plants.  相似文献   

20.
Sun  Junna  Yang  Runya  Zhu  Jinjin  Pan  Yinghua  Yang  Mao  Zhang  Zhenhua 《Journal of Soils and Sediments》2019,19(12):4021-4030
Journal of Soils and Sediments - It is difficult to leach salt into the deep layers of saline or sodic soils due to their poor permeability. The frequency of irrigation is a major factor affecting...  相似文献   

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