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.     

Microbial communities of alluvial soils in the Volga River delta

The number and biomass of the microbial community in the upper humus horizon (0–20 cm) were determined in the main types of alluvial soils (mucky gley, desertified soddy calcareous, hydrometamorphic dark-humus soils) in the Volga River delta. Fungal mycelium and alga cells predominate in the biomass of the microorganisms (35–50% and 30–47%, respectively). The proportion of prokaryotes in the microbial biomass of the alluvial soils amounts to 2–6%. No significant seasonal dynamics in the number and biomass of microorganisms were revealed in the alluvial soils. The share of carbon of the microbial biomass in the total carbon content of the soil organic matter is 1.4–2.3% in the spring. High coefficients of microbial mineralization and oligotrophy characterize the processes of organic matter decomposition in the alluvial soils of the mucky gley, desertified soddy calcareous, and hydrometamorphic dark humus soil types.     

Extraction of urease from soil

Extracellular urease enzyme was extracted with 0·2 m tetra-sodium pyrophosphate from an alpine humus soil, but not from four other soils. The alpine humus soil was high in humified organic matter (17 per cent), and it is suggested that urease may form an enzyme-organic matter complex which protects it from breakdown by protease enzymes.     

Effects of acidification and liming on carbon and nitrogen mineralization and soil organisms in mor humus

The aim was to determine if changes in C and N mineralization after acidification and liming could be explained by changes in the soil organism biomass. Intact soil cores from F/H layers in a Norway spruce (C:N=31) and a Scots pine (C:N=44) stand in central Sweden were treated in the laboratory for 55 days with deionized water (control), weak H₂SO₄ (successively applied as 72 mm of acid rain of pH 3.1), strong H₂SO₄ (applied as a single high dose of pH 1), and lime CaCO₃. Strong acidification reduced C mineralization and increased net N mineralization in both soils. Weak acidification resulted in similar but less pronounced effects. Liming initially stimulated C mineralization rate, but the rates declined, indicating that an easily available C source was successively used up by the microorganisms. Liming also increased net N mineralization in the C:N=31 humus, but not significantly in the C:N--44 humus. Strong acidification generally affected the amounts of FDA-active fungal hyphae, nematodes and enchytraeids more than the other treatments did. The increases in net N mineralization after acidification and liming could only partly be explained by the decreases in biomass N in soil organisms. Mineralization of biomass N from killed soil organisms could at the most explain up to about 30% of the increase in net N mineralization after strong acidification. Most of the effects on N mineralization seemed to depend on the fact that acidification reduced and liming increased the availability of C and N to the microorganisms. Furthermore, acidification seemed to reduce the incorporation of N from dead organisms into the soil organic matter and, thereby, make the N compounds more readily available to microbial decomposition and mineralization.     

长期施肥对褐土有机无机复合性状演变及其与肥力关系的影响

通过8年长期定位试验,研究了不同施肥方式对褐土有机无机复合状况及腐殖质结合形态的影响。结果表明,长期不施肥使土壤有机碳、重组有机碳、原土复合量、松结态和紧结态有机碳含量明显下降,松/紧值降低,原土复合度上升;长期单施常量NPK化肥有同样的趋势;长期单施增量NPK化肥可大体保持土壤肥力水平不下降,但成本较高;采用有机肥(物)料配施常量NPK化肥,可明显提高土壤有机碳、重组有机碳含量和原土复合量以及土壤松、稳、紧各级结合态有机碳含量,增加松结态占重组有机碳比率,提高松/紧值,增强土壤调控能力。土壤有机无机复合状况及腐殖质结合形态是评价褐土培肥效果和标志土壤肥力演变的重要指标。     

Influence of soil properties on urease activity under different agro-ecosystems

Urease activity (by buffer and non-buffer method) of soils of different agro-ecosystems in alluvial soil was studied. Urease activity by buffer method records a higher value than the non-buffer method. Both the methods showed significant positive correlation (0.99**) between each other. Urease activity by both methods showed positive correlation with organic matter (0.88** and 0.89**, buffer method) and clay content (0.91** and 0.83*, non-buffer method)) of the soils. Multiple regression analysis showed that the stabilization of urease activity in the soils studied was due to an organic matter?–?enzyme complex. Among the organic matter humus C plays a dominating role to control the urease activity of the soils.     

Soil organic matter turnover as a function of the soil clay content: consequences for model applications

Based on a literature review including 201 surface soils from wet, mild, mid-latitude climates and 290 soils from the Lower Saxony soil monitoring programme (Germany), we investigated the relationship between soil clay content and soil organic matter turnover. The relationship was then used to evaluate the clay modifier for microbial decomposition in the organic matter module of the soil-plant-atmosphere model DAISY. A positive relationship was found between soil clay content and soil microbial biomass (SMB) C. Furthermore, a negative relationship was found between soil clay content and metabolic quotient (qCO₂) as an indicator of specific microbial activity. Both findings support the hypothesis of a clay dependent capacity of soils to protect microbial biomass. Under the differing conditions of practical agriculture and forestry, no or only very weak relationships were found between soil clay content and non-living soil organic matter C (humus C). It is concluded that the stabilising effect of clay is much stronger for SMB than for humus. This is in contrast to the DAISY clay modifier assuming the same negative relationship between soil clay content, on the one hand, and turnover of SMB and turnover of soil humus on the other. There is a positive relationship between SMB and microbial decomposition activity under steady-state conditions (microbial growth≈microbial death). The original concept of a biomass-independent simulation of organic matter turnover in the DAISY model must therefore be rejected. In addition to the original modifiers of organic matter turnover, a modifier based on the pool size of decomposing organisms is suggested. Priming effects can be simulated by applying this modifier. When using this approach, the original modifiers are related to specific microbial activity. The DAISY clay modifier is a useful approximation of the relationship between the metabolic quotient (qCO₂) as an indicator of specific microbial activity and soil clay content.     

燕山山麓平原高产粮区长期施肥对作物产量和土壤肥力的影响

通过连续 8年长期定位试验 ,研究了不同施肥方式对燕山山麓平原高产粮区褐土土壤肥力和作物产量的影响。结果表明 ,褐土养分贮备及转化潜力较低 ,采用有机肥 (物 )料配施化肥 ,可明显提高土壤有机质和全量养分、速效养分含量 ,促进有机无机复合状况和腐殖质结合形态、腐殖质组成及其性质的改善 ,增强土壤酶群体活性 ,改善土壤水分及物理性质和微团聚体组成 ,较单施常量化肥具有极显著的增产作用。但在配施同量化肥条件下 ,不同有机肥 (物 )料培肥增产效果无显著差异。     

燕山山麓平原高产粮区长期施肥对作物产量和土壤肥力的影响

通过连续 8年长期定位试验 ,研究了不同施肥方式对燕山山麓平原高产粮区褐土土壤肥力和作物产量的影响。结果表明 ,褐土养分贮备及转化潜力较低 ,采用有机肥 (物 )料配施化肥 ,可明显提高土壤有机质和全量养分、速效养分含量 ,促进有机无机复合状况和腐殖质结合形态、腐殖质组成及其性质的改善 ,增强土壤酶群体活性 ,改善土壤水分及物理性质和微团聚体组成 ,较单施常量化肥具有极显著的增产作用。但在配施同量化肥条件下 ,不同有机肥 (物 )料培肥增产效果无显著差异。     

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.     

Some characteristics of the humus in soil types (part 3) composition groups of humus

In most literature on soil, the term humus has been used as synonymous with soil organic matter, on the other hand, it has been applied to a portion of soil organic matter that has decomposed and has lost the structure of the original matter, from which it has derived. Scheffer and Schachtschabel ¹⁾ defined the humus not synonymously with soil organic matter, but, in a broad sense, as all the dead organic substances which are accumulated on the soil surface as well as in the soil layer, and undergo continually decomposition, alteration, and synthetic reactions. According to them, the composition groups of humus are divided into non-humic and humic, and the latter group is sub-divided into (1) fulvic acid and humo-lignin acid, (2) humic acid, (3) humin, and (4) humus coal. Some natures of these composition groups of humus are shown in Table 1.     

Protease extraction from soil by sodium pyrophosphate and chemical characterization of the extracts

Two arable soils and one pasture soil had previously been air-dried for 6 d and stored at room temperature. The enzyme activities remaining after this treatment were constant. The soils were then extracted with 140 mM sodium pyrophosphate at pH 7.1. Amino acid N and total organic C content of soils and soil extracts, together with humic and fulvic acids content of soil extracts were determined. Total organic C was determined in soil residues obtained after extraction. Chemical characterization of the organic matter of soils, soil extracts and soil residues was carried out by pyrolysis–gas chromatography (Py–GC). Protease activity was determined in soil extracts and soil residues by using three different substrates: N-benzoyl- -argininamide (BAA), specific for trypsin; N-benzyloxycarbonyl- -phenylalanyl -leucine (ZPL), specific for carboxypeptidases, and casein, essentially non-specific. Comparative studies between specific activities referred to organic C in soils, soil extracts and soil residues and their corresponding pyrogram composition, and also between total extracted or residual activity and the humine or unhumified organic matter content of the corresponding soil, allowed us to establish hypotheses about the type of organic matter the enzymes are associated with. From 12% to 21% of the soil organic C (33% to 39% of which were humic acids) and from 3% and 18% of amino acid N were extracted from soil using pyrophosphate. Py–GC analyses showed that pyrophosphate was effective in extracting condensed humic substances and glycoproteins and that the organic matter present in soil extracts was especially rich in intact or partially-decomposed fresh residues of carbohydrate origin and also in certain humus-associated proteins. Extracted BAA-hydrolysing activity accounted for 11% to 36% of the soil activity, depending on soil type. Extracted ZPL- and casein-hydrolysing activities were, with one exception, remarkably high, accounting for about 100% or even more of the soil activity, depending on soil type. According to the results BAA-hydrolysing proteases are probably mostly associated with highly condensed humus, ZPL-hydrolysing proteases with less condensed humic substances and casein-hydrolysing proteases with fresh organic matter.     

Chemodestructive fractionation of soil organic matter

The method of chemodestructive fractionation is suggested to assess the composition of soil organic matter. This method is based on determination of the resilience of soil organic matter components and/or different parts of organic compounds to the impact of oxidizing agents. For this purpose, a series of solutions with similar concentration of the oxidant (K₂Cr₂O₇), but with linearly increasing oxidative capacity was prepared. Chemodestructive fractionation showed that the portion of easily oxidizable (labile) organic matter in humus horizons of different soil types depends on the conditions of soil formation. It was maximal in hydromorphic soils of the taiga zone and minimal in automorphic soils of the dry steppe zone. The portion of easily oxidizable organic matter in arable soils increased with an increase in the rate of organic fertilizers application. The long-lasting agricultural use of soils and burying of the humus horizons within the upper one-meter layer resulted in the decreasing content of easily oxidizable organic matter. It was found that the portion of easily oxidizable organic matter decreases by the mid-summer or fall in comparison with the spring or early summer period.     

红松人工林腐殖质组成及其结合形态研究

 运用野外调查与实验分析相结合的方法,对不同生长发育阶段红松人工林（林龄25、45、58、68 a）和红松混交林（林龄60a）根际与非根际土壤有机质含碳量、腐殖质组成与结合形态进行了研究。结果表明:不同年龄阶段红松人工纯林、红松混交林土壤有机质含碳量、腐殖质各组分含碳量随土层深度的加深而降低,并且根际土壤高于非根际土壤。就土壤腐殖质组成而言,除林龄58a红松人工林根际土壤和45a红松人工林非根际土壤外,其他林型土壤胡敏酸含碳量均高于富里酸含碳量;胡敏酸与富里酸比值（HA/FA）在1.00～2.45之间;土壤重组腐殖质、松结态腐殖质、稳结态腐殖质含碳量大小顺序为林龄58>68>25>45a;红松混交林除紧结态腐殖质外,其他腐殖质各组分含碳量均高于红松人工林。     

高量秸秆不同深度还田对黑土有机质组成和酶活性的影响

在田间耕作条件下黑土3个土层(0~20、20~40、40~60cm)添加4%和8%高量玉米秸秆于尼龙袋中原位培养近4年后,研究不同层次土壤秸秆转化与有机碳积累特征,以及腐殖质各组分和土壤酶活性的变化。结果表明,添加4%的秸秆量0~20、20~40和40~60cm土层有机碳分别增加31.8%、96.4%和171.1%,8%秸秆添加量分别增加了86.2%、193.5%和265.9%,增加秸秆还田深度有利于土壤有机碳的积累。0~20 cm土层在无秸秆还田情况下有机碳下降了29.3%,而20~40 cm土层仅下降了1.8%。土壤有机碳含量和酶活性均随秸秆添加量的增加而提高,腐殖质胡敏酸/富里酸(HA/FA)比值发生较大变化,改善了腐殖质品质。各处理腐殖酸碳(HS-C)和胡敏酸碳(HA-C)的大小为20~40 cm土层0~20 cm土层40~60 cm土层,而40~60 cm土层则更有利于富里酸碳(FA-C)的积累。土壤过氧化氢酶活性、脲酶和蔗糖酶活性分别与HA-C、FA-C含量呈极显著正相关、显著正相关。研究结果为深层秸秆还田促进土壤有机质的积累提供了理论依据。     

不同土壤改良措施对低产黄泥田土壤性质及水稻产量的影响

在荆门市双季稻区研究了不同的土壤改良措施对土壤腐殖质组成及结合形态、土壤理化性质、双季稻产量的影响。结果表明：不同土壤改良措施均提高了土壤水溶性物质、胡敏酸、胡敏素含量、可提取腐殖物质总量,其中泥炭土、菇渣及生物有机肥处理增幅较大;不同土壤改良措施增加了土壤松结合态腐殖质、稳结合态腐殖质、紧结合态腐殖质含量及结合态腐殖质总含量,其中生物有机肥处理达到显著水平。各土壤改良措施均不同程度地增加了早、晚稻产量,平均比单施化肥处理的早稻增产6.6％、晚稻增产9.5％;同时提高了土壤有机质、全氮、碱解氮、有效磷、速效钾含量与阳离子交换量,降低了土壤容重。各改良措施中,生物有机肥处理的增产幅度较大,早、晚稻分别增产10.13％和17.50％,且对土壤理化性质的改良效果优于其它处理。     

庐山山地垂直自然带土壤腐殖质与土壤动物分布特征

沿庐山垂直自然带谱对常绿阔叶林(低海拔,L)、落叶常绿混交林(中海拔,M)和落叶阔叶林(高海拔,H)地面腐殖质及大中型土壤动物分布情况进行调查分析,使用调查数据探究了该垂直自然带土壤腐殖质与土壤动物分布特征.调查分析的腐殖质指标有剖面各发生层厚度、O-A过渡层厚度以及A层土壤团粒大小和有机质、总碳量、全磷、全氮、全碳含...     

不同开垦年限黑土有机质变化的研究

本试验研究了不同开垦年限黑土有机碳的数量、组成、结合形态的变化 ,试验研究结果表明 :垦后黑土 0～2 0cm土层土壤有机碳数量不断下降 ,年有机碳矿化速率为 1 72 % ,达到平衡后有机碳数量为 7 2 7g/kg ,土壤有机碳的H/F比升高 ,氧化稳定性增强 ,土壤有机—无机复合度升高 ,土壤有机碳松紧比下降。 2 0～ 40cm土层土壤有机碳在垦后 2 2年内升高 ,以后又下降 ,土壤H/F比无显著变化规律 ,土壤有机质氧化稳定性提高 ,土壤有机—无机复合度下降 ,土壤松紧比下降     

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.