Stable and labile components of humus in soddy-podzolic soils

A mathematical model was proposed to characterize the seasonal dynamics of the humus composition in loamy soddy-podzolic soils. The results of determining the composition of the organic matter during two successive seasons revealed the presence of labile and stable components in almost all the groups and fractions of the humic substances. The seasonal changes in the content of the humic substances, the exchangeable Ca, and the pH value at the equilibrium state of the soil were found to be identical during the successive years.     

Transformation of the soil organic matter under the extreme pollution by emissions of the Severonikel smelter

The direct impact of the long-term extreme pollution by emissions of the Severonikel copper-nickel processing plant per se is not capable of inhibiting the organic matter transformation even within the local zone of this enterprise. However, a great number of indirect pollution factors can affect the organic matter content and the composition of the soils in the local zone. The destruction of the vegetation and the changes in the amount and botanical composition of the falloff influence the soil humus status to the greatest extent. As fresh falloff is absent, the old (formerly accumulated) organic matter of the soils is gradually mineralized, and its content decreases. In the most damaged ecosystems of the local zone, the soils have lost almost all their organic matter, and their properties are returning to those of the initial parent rock. The disturbance of the water regime of some ecosystems and of the whole landscape intensifies the migration of substances within the soil profiles and in the whole landscape. This is the second by significance factor affecting the humus status of the soils in the local zone. The transformation of the organic soil profiles under the influence of the indirect factors is sufficient to change their taxonomic position at the level of subtypes or type.     

Fractional composition of humus in leached chernozems and gleyed podzolized chernozem-like soils of the northern forest-steppe zone

The composition of humus in leached chernozems differs from that in gleyed podzolized chernozem-like soils in the northern forest-steppe zone of European Russia. Leached chernozems have the fulvate-humate humus. Gleyed podzolized chernozem-like soils have the humate-fulvate humus. A more aggressive composition of humus in the latter soils is caused by their overwetting and the development of gley processes under conditions of a stagnant-percolative soil water regime.     

Transformation of humus substances in the long-drained surface-gleyed soddy-podzolic soils under conditions of pronounced microrelief and different agrogenic loads

The transformation of humus substances resulting from artificial drainage of the surface-gleyed soddy-podzolic soils under conditions of pronounced microtopography and different agrogenic loads was studied. The studied soil characteristics included acid–base conditions, the content and group composition of humus, the ratios between the fractions of humus acids, and optical density of humic acids. The features attesting to humus degradation were found in the soils of microdepressions periodically subjected to excessive surface moistening, in the soils of different landforms upon the construction of drainage trenches, and in the plowed non-fertilized soils. The response of humus characteristics to the changes in the ecological situation in the period of active application of agrochemicals for reclamation of the agrotechnogenically disturbed soils was traced. It was shown that the long-term dynamics of the particular parameters of the biological productivity of the soil depend on the hydrological and agrogenic factors, as well as on the weather conditions.     

Liming effect on dissolved organic matter leaching

The main agrochemical treatment applied in agriculture to lower harmful soil acidity is liming. Long term studies showed that application of calcium carbonate fertilizer brought about higher leaching of dissolved organic matter (DOM) in pot, lysdmetric and field experiments. Outflows obtained from limed soils contained 44.8% more DOM in comparison with nonlimed soils. During four years of lysimetric experiments it was found that the amounts of DOM from limed soils were increased by 52.7%. In the field experiments the amounts leached from one hectare of limed and nonlimed soil ranged 25.6 kg and 19.2 kg per year, respectively. DOM leached from limed soils was characterized by higher (45.4%) contents of carboxylic groups and humic substances (19.7%). Dissolved organic substances particularly humus rich in functional groups, due their complexing properties bound plant nutrients leached from soils and modify geochemical mobility of metals and anions. Therefore, DOM can play a significant role in the migration of chemical substances in agriculture landscape.     

Properties of soils in Southern Sikhote-Alin using the example of the Ussuri Reserve

The physical and physicochemical parameters of soils in the Ussuri Reserve presenting the typical soils of the Southern Sikhote-Alin were determined for the first time with consideration for the composition and structure of the soil cover. The soils in the surface horizons had loamy and clay loamy texture. It could vary depending on the overlain soil processes. All the soils were characterized by the minimum base saturation and an increase in the actual acidity down the profile. The organic matter was characterized by an abrupt decrease down the profile and the high mobility of the humus substances. The fractional-group humus composition was analyzed, and the humus status of the soils was characterized. The burozems were regarded as background soils, while a humus-illuvial podburs were referred to the rare ones. Recommendations were developed for the organization of soil monitoring with key test plots in different ecological conditions as examples.     

Humus Horizons of Soils in Urban Ecosystems

The origin, structure, composition, and properties of soil humus horizons in functional zones of St. Petersburg have been studied. The radiocarbon age of organic matter in the humus horizons varies from 500 to 2700 years, which attests to the natural origin of humus. The structure of microbiomes in the humus horizons of soils under different plant communities has its specific features. The taxonomic structure of microbial communities at the phylum level reflects both genetic features of natural soils and the impact of anthropogenic factors, including alkalization typical of the studied urban soils. Tomographic studies have shown that the transporting system of humus horizons is less developed in the anthropogenically transformed soils in comparison with the natural soils. It can be supposed that the intensity of water and gas exchange in the anthropogenic soils is much lower than that in the natural soils. The fractional and group composition of humus in the urban soils is specified by the long-term pedogenesis, on one hand, and by the impact of metabolic products of the city and the factors of soil formation in the megalopolis, on the other hand. Bulk density of the humus horizon in the urban soils is higher than that in the natural soils; the portion of overcompacted humus horizons in the urban soils reaches 44%. Humus horizons of the lawns along highways are most contaminated with heavy metals: Pb, Zn, and Cu. There are no definite regularities in the distribution of major nutrients (NPK) in the humus horizons of anthropogenic soils.     

Humus status of buried soils in loess deposits of the Minusinsk intermontane trough

The study of the humus status of the buried soil sequence in loess deposits of the Minusinsk intermontane trough revealed that the group humus composition and humus properties of the buried soils did not undergo considerable changes and preserved their initial parameters upon the burial under the conditions of low biological activity. Neither the group humans composition nor the humus substance properties fell beyond the limits typical of the humus status of recent soils. The fractional composition of the humus acids might undergo secondary alternations after the burial. The dependence between the humus type and the length of the biological activity period permitted us to make a paleoclimatic reconstruction of the bioclimatic conditions that might have existed during the formation of the loess deposits in the Minusinsk intermontane trough. It was shown that the soil-climatic zones were repeatedly alternating during the Quaternary period due to the global climate change.     

Humus status of soils of overgrown quarries in Leningrad oblast

The humus status of young different-aged soils developed on tailings of different quarries of Quaternary and pre-Quaternary raw materials in Leningrad oblast was studied. Organic profiles were characterized; the humus accumulation rates, the organic matter reserves, the humus enrichment with nitrogen, the degree of humification of the organic matter, and the contents of separate fractions of humus acid in soils on different tailing rocks were estimated. The composition of humic acids was also studied. It was shown that the lithological features of the tailings determining the chemical processes of the profile differentiation of humic substances and the ecogenetic successions of vegetation also determine the rate and direction of the humus accumulation in the soils during similar periods of biological activity in the southern taiga.     

Prospects and problems of using the methods of geochemistry of stable carbon isotopes in soil studies

A review of world investigations into the geochemistry of stable isotopes—a new area for soil science—is presented. Studies of the behavior of stable isotopes in soils are being developed in two major directions: reconstruction of the environmental conditions and indication of the soil processes. Investigations into the reconstruction of the environmental conditions are based on the assumption that the isotopic composition of carbon in the soil humus is inherited from and reflects the isotopic composition of carbon in the corresponding vegetation (the source of soil humus). At the same time, studies into the indication of soil processes are based on the effects of fractionation of carbon isotopes in the course of transformation of carbon compounds. In this case, the isotopic composition of carbon in the soil humus should differ from that in the initial plant material. The analysis of available data suggests that the current state of research does not allow assessing the entire diversity of the effects of isotopic fractionation in soils. New data on the isotopic composition of carbon of soil organic matter and carbonates are being actively accumulated at present. However, it is obvious that the effect of isotopic fractionation should be taken into account in the paleoenvironmental and paleoclimatic reconstructions.     

Changes in the Content,Composition, and Properties of Humic Substances in Particle-Size Fractions of Soddy-Podzolic Soils under the Impact of Long-Term Drainage

Specific features of the transformation of humic substances in particle-size fractions of drained soddy-podzolic soils were studied on a field (12 ha) of the Experimental and Educational Center of Lomonosov Moscow State University in Moscow oblast. The field had a clearly pronounced microtopography. Surface-gleyed soddy-podzolic soils (Albic Stagnic Glossic Retisols (Loamic, Aric, Ochric)) of microdepressions with excessive surface moistening and nongleyed soddy-podzolic soils (Albic Glossic Retisols (Loamic, Aric, Ochric)) of elevated positions were examined. These soils were studied before the field drainage and during 25 years after drainage works in the periods differing in conditions of humification and with due account for not only drainage works but also other factors, such as topography and agrotechnology and their joint action. The specificity of transformation of humic substances in the soils and their particle-size fractions was analyzed in the basis of data on the organic carbon content, group and fractional composition of humus, the intensity of individual stages of humification (the neoformation of humic acids and the formation of humates), and the optical density of the fractions of humic acids. The results of the study of these properties in the fine soil fractions (<50 μm) made it possible to assess the response of the clay (<1 μm) and silt (1–5, 5–10, 10–50 μm) fractions to changes in the ecological situation and the role of separate particle-size fractions in the degradation of humus under adverse impacts. Overall, a clear tendency toward worsening of the humus quality was observed in both soils during the 25-year-long period, which is related to the long-term (20 years) agricultural use of the reclaimed field without application of agrochemicals. The features of humus degradation were mainly manifested in the finest (<10 μm) fractions with a general decrease in the humus content, slowing down of the formation of humic acids and humates, and considerable loss of humic acids, including their agronomically valuable fractions HA1 and HA2. The degradation of humus quality in the clay fraction was largely due to the impact of the reclamation (drainage) factor; the degradation of humus quality in the fine and medium silt fractions was mainly due to the negative changes in the agricultural background. Among negative consequences of the worsening humus quality, the lowering of soil fertility, ecological sustainability, and productivity of agrocenoses should be noted.     

我国几种土壤中腐殖质性质的研究

研究了几种土壤腐殖酸的基本性质,其中包括土壤的腐殖质组成,胡敏酸以及富里酸的元素组成,含氧官能团含量,光密度值与芳化度等,计算了E₄与E₄/E₆比值与上述性质的相关系数。结果表明土壤腐殖质组成和性质与其形成条件有着密切的联系,并且有一定的地带规律性。水稻土中有机质含量增加,HA/FA比值变高,其活性HA显著降低,说明水稻土有利于有机质的积累并改变了腐殖质的组成。E₄、E₄/E₆比值与元素组成,C/H比值,含氧官能团及芳化度之间的相关系数表明E₄除了与C%,O%,酚羟基-O%,醌基-O%呈极显著或显著相关外,还与C/H比值及芳化度呈极显著相关,因此E₄值可作为腐殖物质芳化度的一个指标。     

卧龙自然保护区森林土壤有机质的研究

研究了四川卧龙自然保护区不同海拔高度的五种植被(常绿阔叶林、落叶阔叶林、针阔混交林、暗针叶林和高山草甸)下的土壤中有机质的含量、组成和性质。主要结果如下。1.各土壤虽然生物气候条件差异悬殊,但其腐殖质均属于富里酸型。2.落叶阔叶林、针阔混交林和暗针叶林下的粗腐殖质也属于富里酸型;红外和紫外光谱说明,它们和“成熟的”腐殖酸有明显的不同。3.土壤有机质含量与土壤物理性质和速效性养分含量有密切的关系。     

Transformation of humic substances in soddy-podzolic soils under agrogenic impacts

The transformation of humic substances in soddy-podzolic soils under agrogenic impacts of different intensities and durations was studied. Indices of the initial stages of degradation and regradation of soil humus were revealed, and the humus status of soils under different fertilizing conditions was estimated.     

Über Veränderungen im Humuskomplex bei der Degradation von Schwarzerden (Tschernosemen)

Dynamics of organic matter during the degradation of Chernozems In the course of pedogenesis especially the amount and the composition of soil organic matter changes. This is investigated in the presented paper at 6 different developmentstages of a Chernozem-degradation-sequence from Hildesheim region. The mechanisms of this process can be deduced from the ‘degradation products’, found in the different soils. Using several methods for extraction of organic substances by successively stronger reagents or conditions, different amounts of fulvic and humic acids were got. The findings give indications to the different stability of bondings between mineral and organic substances in the soils and their change during degradation. The ascending exhaustive fractionating method was found to be the best for obtaining and-simultaneously - separating completely the organic matter in distinct franctions and also to earn a humus-clay and a silica humic acid component. Using this method, 5 fractions of the humus complex at any of profile-horizons were got in greater amounts and quantitative as far as qualitative determined. It was found that the loss of organic matter is differently distributed to the single humus fractions in the profiles and in the horizon-zones. Therefore it is not sufficient to determine only the total C- and N-content. Comparing the increase or decrease of humic substances in the upper resp. lower zones of the profiles of the sequence, the degradation process can be pursued retrospectively.     

Characteristics of dissolved organic matter and phenolic compounds in forest soils under silver birch (Betula pendula), Norway spruce (Picea abies) and Scots pine (Pinus sylvestris)

The aim was to characterize dissolved organic matter in soils under different tree species. Molecular size distribution and chemical composition of dissolved organic carbon and nitrogen were determined in water extracts from humus layers and mineral soils taken from silver birch ( Betula pendula Roth.), Norway spruce ( Picea abies (L.) Karst.) and Scots pine ( Pinus sylvestris L.) stands. Concentrations of tannins and 15 phenolic acids in the humus layers were measured. Per unit of organic matter, the concentrations of dissolved organic C and N were larger in birch and spruce humus layers than in the pine humus layer. In the underlying mineral soil, the concentrations of dissolved organic C were similar at all sites, but the concentration of dissolved organic N was greater in spruce and pine soils than in birch soil. In all soils, the 10–100 kDa fraction was the most abundant molecular size group and hydrophobic acids the most abundant chemical group of dissolved organic C. In all humus layers, hydrophobic acids and hydrophilic bases were the major components of dissolved organic N. There were only minor differences in the concentrations of total tannins in the humus layers under different tree species. Small-molecule tannins (about < 0.5 kDa) were most abundant in the birch humus, and large-molecule tannins in the pine humus. Coniferous humus contained more ferulic and p -coumaric acids than did the birch humus. The concentrations of 3,4 and 3,5-dihydroxybenzoic acid, vanillic acid and 4-hydroxybenzoic acid were similar in all soils.     

Biological mineralization of organic matter in the modern virgin and plowed chernozems,buried chernozems,and fossil chernozems

The phenomenon of mineralization (biological mineralization) of organic matter in chernozems has been studied. A decrease in the content of C_org with time can be considered an index of the organic matter mineralization. It is suggested that the humus horizons of modern chernozems contain the pools of organic matter of different ages: easily decomposable organic matter, labile biologically active humus, stable biologically active humus, and relatively inert humus. The composition and mean residence times of these pools and their contribution to the total organic matter content have been estimated. The particular types of the biological mineralization have been determined on the basis of the comparison between the velocities of mineralization (M) and humification (H) processes: total unidirectional mineralization (M ≫ H), equilibrium mineralization (M ∼ H), nonequilibrium mineralization (M> <H), and zero mineralization. The separation of subtypes is based on data on the relative rates (%) of the organic matter mineralization. On the basis of available experimental data on chernozems buried under kurgans and in loess sediments (with the age of up to 800 ka), the quantitative relationship of the humus content in the buried soils on their age has been found; it has an exponential shape. During the first 100 ka after the soil burial, the soil humus content gradually (with a slowing intensity) decreases from 100–75 to 6.5% of its content in the virgin chernozems. Then, 100–1000 ka after the soil burial, the soil humus content remains approximately constant (6.5% of the initial level, or 0.3% of the soil mass). The rates of mineralization have been estimated. It is shown that the elemental composition (C, H, N, O) of humic acids remains relatively stable for a long time due to the regeneration of the chemical structure of humus (matric restoration of humus). It is suggested that several different forms of humus related to pedogenesis should be distinguished in the biosphere. The renewable humus in the equilibrium state with the environment is typical of the open biospheric (soil) systems. The fossil humus, whose content decreases with time, and whose composition remains stable, is typical of the semiclosed and closed systems. With time, it transforms into residual humus, whose content and composition remain stable. The fossilized organic matter in the fossil soils and sediments of the past geological epochs (Mesozoic and Paleozoic) considerably differs from the renewable, fossil, and residual humus.     

长期施磷对山原红壤磷库组成及有效性的影响

通过33年施肥试验研究了不同施磷处理对山原红壤中磷素形态转化及含量的影响。结果表明,长期施用磷肥增加了红壤中全磷和速效磷的含量;施磷处理下土壤表层无机磷、有机磷显著积累。不同施肥处理下土壤无机磷组分均以Fe-P为主,占总量的50%左右;相关分析表明无机磷组分中的Fe-P、Al-P与速效磷分别呈极显著正相关(r=0.908)、显著正相关(r=0.706),表明Fe-P、Al-P为山原红壤的有效磷源。对于土壤有机磷而言,所有施肥处理的土壤中稳性有机磷比例最高,其次为中等活性有机磷,再次为高稳性有机磷,活性有机磷最低,前二者占有机磷总量的90%左右。有机磷组分与速效磷的相关性分析结果表明,中等活性有机磷、中稳性有机磷分别与土壤速效磷呈极显著正相关(r=0.861)、显著正相关(r=0.840)。说明中等活性有机磷和中稳性有机磷是土壤速效磷的主要来源。增施磷肥尤其是氮、磷、钾肥与农家肥配施后,可促进其他形态有机磷向有利于作物吸收的中等活性有机磷、中稳性有机磷转变。     

Composition and pools of humus in natural and agrogenic soils of the Kamchatka Peninsula

Differentiation of Kamchatka soils with respect to the composition and pools of humus is discussed. Very low and low pools of humus of the fulvate type are typical of the ocherous and stratified ocherous volcanic soils of the eastern coastal zone and the Central Kamchatka Depression. Ocherous volcanic soils of the Western Kamchatka Lowland are characterized by the low and moderate pools of the humate–fulvate humus. Agrogenic soils are characterized by the higher pools of humus in the upper 20 cm in comparison with their natural analogues, which is largely related to changes in the physical properties of the soils under the impact of tillage.     

Specific features of organic matter in urban soils of Rostov-on-Don

Data on the fractional and group composition of humus in urban soils of Rostov-on-Don are discussed. We have compared the humus profiles of chernozems under tree plantations and those buried under anthropogenic deposits (including sealed chernozems under asphalt). It is shown that the type of humus in these soils remains stable despite a decrease in its total content after the long-term burial under asphalt. Under the impact of the trees, the organic matter of the chernozems acquired some features typical of gray forest soils, i.e., the humate-fulvate type of humus in the humus horizon and the sharp drop in the humus content down the soil profile.