粘土矿物对土壤腐殖质化学性质的影响

Chemical characteristics of humic substances in soils with different mineralogical characteristics and under different utilization paterns in Zhangpu,Fujian Province,together with two pairs of cultivated soils in North China Plain were studied by chemical analysis,visible and IR spectroscopy and ^13C NMR spectrometry.For soils in Zhanpu the HA/FA ratio and both the aromaticity and the degree of humification of HA were higher in soils with montmorillonite as the predominant clay mineral than in those with kaolinite as the predominant clay mineral,provided these soils were under the same utilization pattern.While for each pair of soils with similar mineralogical characteristics the HA/FA ratio was higher and the C/H ratio and the contnet of carboxyl group of HA were lower in paddy soil than in upland soil.Among the upland soils(or paddy soils)studied the Ha/FA ratio of soil in Zhangpu with kaolinite as the predominant clay mineral was the lowest,and that of soil in Zhangpu with montmorillonite as the predominant clay mineral was the highest .the lowest.and that of soil in Zhangpu with montmorillonite as the predominant clay mineral was the highest It was concluded that the presence of montmorillonite favored the fromation and maturation of humic acid.     

Changes in some physical properties of soils in the chronosequence of self-overgrown dumps of the Sokolov quarry-dump complex,Czechia

The water-physical properties (bulk density, air conductivity, texture, water content, and temperature dynamics) were studied in a chronosequence of soils developing on self-overgrowing quarry-dump complexes in the area of Sokolov, Czechia. The area overgrown for 12 years was covered by a thin grass cover; osiers were observed after 20 years of overgrowth; a broadleaved forest was found on a plot after 45 years of overgrowth. The particle-size distribution in the soil was determined using peptization by pyrophosphate and the FAO method. When the soil was prepared by the FAO method, a predominance of physical clay (62–72%) in the dump material was revealed; at the use of pyrophosphate peptization, the content of this fraction was lower (18–19%). The observed differences can be due to the incomplete degradation of the microaggregates composed of clay particles during the peptization by pyrophosphate. A decrease in the field water content of the soils with the increasing time of the dump’s overgrowth was observed. This could be attributed to the more significant evapotranspiration of the perennial woody vegetation compared to the herbaceous plants, which agreed with the data on the projective cover of plants and their root biomass. A decrease in the soil temperature in the root-inhabited layer (in the diurnal variation) with the age of succession was also observed. The analysis of the data on the field soil water content and their comparison with the results of the laboratory measuring of the wilting points indicated that the development of plants could be restricted by a water deficit at the 20- and 45-year-old stages of the succession.     

Accumulation of carbon,nitrogen and phosphorus during soil formation on alder spoil heaps after brown-coal mining,near Sokolov (Czech Republic)

The accumulation of carbon (C), nitrogen (N) and phosphorus (P) and their vertical distribution in the soil profile in relation to site age were studied in a chronosequence of 19 sites on reclaimed spoil heaps from open-cast coal mining, near Sokolov (Czech Republic) and compared to a semi-natural alder forest in the vicinity of the mining area. The reclaimed sites were located on tertiary clay or quaternary gravel–sand spoil material and afforested with alder species (Alnus glutinosa, A. incana) 4–65 years ago.Rapid accumulation of C and N in the soil profile was registered within 15 years after reclamation. The rate of increase in C and N contents in the whole profile and the thickness of the litter and fermentation layers was slower in 25-year-old and older reclaimed sites. The soil of the semi-natural alder forest was richer in C and N in the 5–10-cm layer compared with 40-year-old (clays) and even with 65-year-old (gravel–sand) reclaimed soils. N accumulated more slowly in comparison with C, especially in deeper (5–10 cm) parts of the profile. Accumulation of organic C resulted in a decrease in substrate pH from alkaline, which was characteristic of young sites, to slightly acidic on older sites. The pH decreased gradually with increasing site age in all soil layers but increased with depth in the soil profile. In contrast to C and N, P content did not significantly change with site age in any layer of the soil profile. The highest amount of P was found in the fermentation layer, but there was no difference to the other layers. The soil profile of the semi-natural sites was richer in P in comparison to 40-year-old reclaimed ones.     

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.     

红壤复合胶体腐殖质的特性

对闽北6个样品测定结果表明,红壤复合胶体中C、N含量较高,其腐殖质的C/N和HA/FA、胡敏酸的芳构化度和腐殖质氧化稳定性系数均较重组小,而松结合态/紧结合态腐殖质的比值则较大.这些特性有利于土壤养分保存与供应和改善土壤结构.     

A comparison of the effectiveness of various extractants for determining humus quality in a calcareous soil

Abstract

Humic substances from an Argentinian chesnut (Mollisol) soil were extracted with Na‐Dowex A‐1 resin, 0.1 N NaOH and 0.1 M Na₄P₂O₇ without decalcification and with 0.1 N NaOH after decalcification. Humic to fulvic (Ch/Cf) acid and E₄/E₆ ratios of the extracts were determined and compared.

A simpler and more rapid procedure than the classical ones for extracting and characterizing soil humus is proposed. The procedure is based on the use of a chelating resin as extractant and on the direct determination of analytical properties of humus in aliquots of the extract.     

Changes in the humus status of a layland sandy gleyic soddy-podzolic soil

Changes in the content, reserves, and composition of humus in a sandy gleyic iron-humus-illuvial soddy-podzolic soil under intensive, decreasing, and ceased agrotechnical impacts were studied. It was shown that when a well-cultivated soil is removed from economic use, the conditions of humus formation in the former homogeneous plow layer develop differently. A deterioration of the humus status parameters of the layland soil was found as compared to the cultivated soil. It was concluded that, when a soil is removed from economic use, its profile, which was disturbed by the anthropogenic impact, tends to return to the original genetic state. The change in the level of the agricultural practices affected the optical density of the humic acids only slightly, which is indicative of their relative stability under specific soil-forming conditions.     

Elemental composition and structural features of humic substances in young podzols developed on sand quarry dumps

Data were analyzed on the elemental composition of humic and fulvic acids isolated from organic and mineral horizons of different-aged podzols developed on sand quarry dumps in Leningrad oblast. It was shown that the humic substances from the young podzols significantly differed from those isolated from the mature soils. The humic acids (HAs) of the young podzols composed a more homogeneous group of natural compounds compared to the fulvic acids (FAs). The HAs isolated from the organic, podzolic, and illuvial horizons of the embryopodzols significantly differed in their structure. The litter HAs were characterized by the minimum aromaticity and the maximum content of aliphatic components. The HAs from the illuvial horizons contained the maximum portion of aromatic components; a significant portion of carboxyls, ethers, polysaccharides, carbohydrates, and amino acids; and the minimum portion of aliphatic components. The HAs from the podzolic horizons occupied an intermediate position between the humic substances of the organic and illuvial horizons. It was shown that Mendeleev’s formula was more suitable than Aliev’s formula for calculating the calorific values of the HAs because of their structural features. Based on the particular features of the humic substances studied, they were classified as prohumic substances.     

Long-term effect of straw and farmyard manure on soil organic matter in field experiment in the Czech Republic

The effect of long-term (45 years) mineral and organic fertilization on soil organic matter (SOM) quantity (organic C and N content) and quality (hot-water-soluble C content, microbial biomass C content, hydrophobic organic components of SOM, soil enzyme activities) was determined in a field experiment established in Trutnov (North Bohemia, sandy loam, Eutric Cambisol). Six treatments were chosen for investigation: unfertilized control, mineral fertilization (NPK), straw N, farmyard manure (FYM) and straw and FYM completed with mineral NPK. Soil samples were taken from the arable layer (0–20 cm) in spring over the period of 2004–2010. The positive effect of FYM on the total organic C and N content, hot-water-soluble C content and hydrophobic organic components of SOM was more than 50% higher than that of straw and mineral N fertilization. Application of straw N increased microbial biomass C content in soil and generated invertase activity above the level of FYM. Hot-water-soluble C content, hydrophobic organic components of SOM and urease activity were positively correlated with total organic C and N content (R = 0.58–0.98; p < 0.05). Addition of mineral NPK to both the straw and FYM emphasized the effect of organic fertilization in most of monitored characteristics.     

Cadmium and lead affect the status of mineral nutrients in alfalfa grown on a calcareous soil

ABSTRACT

Cadmium (Cd) and lead (Pb) are toxic trace elements which are not essential for plants but can be easily taken up by roots and accumulated in various organs, and cause irreversible damages to plants. A pot experiment was carried out to investigate the individual and combined effects of Cd (0, 10, 20 mg kg^?1) and Pb (0, 500, 1000 mg kg^?1) level in a calcareous soil on the status of mineral nutrients, including K, P, Ca, Mg, S, Fe, Mn, Cu, and Zn, in alfalfa (Medicago sativa L.) plants. Soil Pb level considerably (P ≤ 0.05) affected the concentrations of more elements in plants than soil Cd level did, and there were combined effects of soil Cd level and Pb level on the concentrations of some nutrients (Ca, Mg, and Cu) in plants. The effects of soil Cd level and Pb level on plant nutrient concentrations varied among plant parts. Cd and Pb contamination did not considerably affect the exudation of carboxylates in the rhizosphere. An increase in rhizosphere pH and exudation of significant amounts of carboxylates (especially oxalate) in the rhizosphere might contribute to the exclusion and detoxification of Cd and Pb. Neither shoot dry mass nor root dry mass was significantly influenced by soil Cd level, but both of them were considerably reduced (by up to 25% and 45% on average for shoot dry mass and root dry mass, respectively) by increasing soil Pb level. The interaction between soil Cd level and Pb level was significant for root dry mass, but not significant for shoot dry mass. The results indicate that alfalfa is tolerant to Cd and Pb stress, and it is promising to grow alfalfa for phytostabilization of Cd and Pb on calcareous soils contaminated with Cd and Pb.     

Influence of geogenic CO2 on mineral and organic soil constituents on a mofette site in the NW Czech Republic

Geogenic CO₂ emission on mofette sites may be a factor in soil formation. To demonstrate a CO₂ effect, we studied soils (0–60 cm depth) along a transect across a mofette in the NW Czech Republic. We determined CO₂ partial pressures (p(CO₂)), and the contents in the soil of carbon (C), nitrogen (N), sulphur and dithionite‐ and oxalate‐extractable iron and manganese. X‐ray diffractometry (XRD) and Fourier‐transform infrared (FTIR) spectroscopy methods were applied to the soils' particle‐size fractions. The CO₂ partial pressures varied considerably (0.001–1) along the transect and were positively correlated with both the C_org contents (5.5–432.9 g kg⁻¹) and the C:N ratio (9.3–32.2), indicating a decreased turnover of organic parent material with increasing CO₂. When the soil atmosphere was entirely composed of CO₂, pedogenic Fe oxide contents were small (minimum 0.5 g dithionite‐extractable Fe kg⁻¹) and poorly crystalline. XRD and FTIR spectroscopy revealed primary and secondary minerals such as quartz, feldspars, mica, illite, kaolinite and halloysite irrespective of CO₂ contents. A pronounced effect of CO₂ was found for soil organic matter (SOM), because the FTIR spectra did not reveal a normal accumulation of alkyl C and lipids of microbial origin in the clay fraction. This indicates that microbial synthesis and/or degradation of plant‐derived aliphatic species were reduced. We did not detect more organo–mineral associations, microbially formed polypeptides or pectin in clay fractions in comparison with the clay‐plus‐silt fractions at large p(CO₂). This indicates relatively unaltered particulate OM in the clay fraction. At large p(CO₂) values, the IR bands indicative of lignin became detectable and that of aryl ketones in lignin was positively correlated with p(CO₂). Thus, we suggest that microbial formation of SOM and degradation of lignin is restricted under an increased CO₂ atmosphere. We attribute less humification at increased CO₂ in the soil atmosphere to a decrease in oxidative transformations and decreased microbial activity.     

Nutrient status of soil and winter wheat (Triticum aestivum L.) in response to long-term farmyard manure application under different climatic and soil physicochemical conditions in the Czech Republic

Long-term field experiments with annual crop rotation were established in 1955 and 1956 at three locations (Lukavec, ?áslav, Ivanovice) in the Czech Republic, which differ in their climate and soil physicochemical properties. The effect of cattle farmyard manure (FM) and a combination of FM and mineral (NPK) fertilizer application (FMNPK) on nutrient status of soil and the response of winter wheat, and nutrient content of wheat grain and straw were evaluated after ~60 years since the establishment. The results showed higher pseudototal (aqua regia soluble) contents of phosphorus and sulfur from FM and FMNPK application compared with control, whereas the labile and moderatory labile content of individual nutrients (except calcium) varied between treatments. The nutrient content of wheat grain and straw was more significantly (p < 0.05) affected by the location and growing season than by the fertilizers. The substantial changes in wheat nutrient uptake occurred for the weakly acidic loamy Gleyic Phaeozem, whereas the lowest response due to fertilizer application was observed for the acidic Cambisol (sandy loam texture). Even after six decades of FM and FMNPK application, the effectiveness of these treatments was predominantly influenced by the soil and climatic conditions at the individual locations.     

The effect of site characteristics and farming practices on soil organic matter in long-term field experiments in the Czech Republic

Parameters for evaluating both the soil organic matter quantity (total organic C [TOC]) and quality (hot water extractable C [HWC], hydrophobic and hydrophilic components, soil hydrophobicity) were determined in soil samples taken from selected plots of 13 field experiments under different soil and climatic conditions in the period 2004–2008. Four variants were selected in each experiment: non-fertilized control (Nil), mineral fertilized variant (NPK), farmyard manured variants (FYM) and organic and mineral fertilized variants (FYM + NPK). The TOC and HWC content of topsoil differed mainly as a result of the site conditions. Both organic and mineral fertilization increased the TOC content of soil; the percentage increase in the HWC content was greater than that for the TOC content. Mineral and organic fertilization increased the hydrophobic organic component content but not the hydrophilic organic component content. A significant positive correlation was found between hydrophobic organic components and HWC content (R = 0.746, P < 0.01). Hydrophilic organic component content was highly significantly correlated with the TOC content (R = 0.728, P < 0.01). Soil hydrophobicity was affected by soil texture and clay content, and a positive effect of long-term organic fertilization on soil hydrophobicity, and thereby soil stability, was determined.     

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.     

秸秆还田深度对黑土腐殖质和酶活性的影响

在田间条件下对耕地黑土3个土层(0~15、15~30、0~30 cm)进行玉米秸秆还田试验,研究不同秸秆还田深度土壤腐殖质各组分含量、土壤酶活性的变化及其相关性。结果表明:还田深度0~15、15~30、0~30cm土壤总有机碳含量与初始相应层次土壤分别增加9.5%、9.9%、10.7%,与0~15 cm相比,秸秆还田深度为15~30 cm时,有利于土壤有机碳的积累。与初始相应层次土壤比,未秸秆还田的土壤总有机碳含量降低了5.8%。土壤各组分有机碳含量与土壤蔗糖酶活性之间显著(或极显著)相关,土壤胡敏素碳含量与土壤过氧化氢酶活性之间显著相关,土壤富里酸碳含量与土壤脲酶活性之间显著相关。     

Specific features of the humus status in soils of Buryatia

The humus content in soils of Buryatia varies significantly in dependence on the local hydrothermic conditions. All the studied soils are characterized by a relatively short humus profile, a sharp drop in the humus content down the soil profile, considerable amounts of the humin fraction and the fraction of humic acids bound with sesquioxides, and a moderate humus enrichment with nitrogen.     

现代分析技术在土壤腐殖质研究中的应用

土壤腐殖质的研究已成为土壤学、环境化学和地球化学等领域的热点方向之一。应用核磁共振光谱 (NMR)、红外光谱 (IR)、荧光光谱 (FS)、电子自旋共振谱 (ESR)等现代分析技术 ,对在土壤腐殖质组成和结构研究中取得的主要成果进行了综述。     

两种生物质炭对酸性紫色土腐殖质组成的影响

生物质炭的性状与原料中木质纤维含量密切相关,为探明不同原料生物质炭对土壤腐殖质组成的影响,选取玉米秸秆和紫茎泽兰分别作为纤维类和木质类原材料制备生物质炭,向酸性紫色土分别添加5%玉米秸秆生物质炭（MB）和5%紫茎泽兰生物质炭（EB）,测定90 d室内培养期间土壤胡敏酸（HA）、富里酸（FA）、胡敏素（HM）含量以及HA光学性质和元素组成变化。结果表明：MB和EB的比表面积分别为2.32 m²·g^-1和0.72 m²·g^-1,总孔体积分别为42.71 mm³·g^-1和12.59 mm³·g^-1,碳与氢元素摩尔比（C/H）分别为1.91和1.46,氧、硫之和与碳元素摩尔比[（O+S）/C]分别为0.09和0.16,玉米秸秆生物质炭的吸附能力更强、有机质成分的缩合度更大且氧化度更小。与对照（不添加生物质炭,CK）相比,培养结束后,施入生物质炭的土壤HA、FA和HM含量分别显著增加（P<0.05）65.59%~102.82%、85.87%~118.54%和137.25%~161.23%,MB处理对这3种腐殖质含量的增加效应较EB处理更明显。培养结束时添加生物质炭的土壤HA/土壤有机碳（SOC）降低13.53%~27.06%,FA/SOC降低6.81%~18.03%,其中EB处理的降低效应达显著水平;HM/SOC则增加4.58%~11.40%,其中MB处理的增加效应达显著水平。添加生物质炭的土壤HA色调系数（ΔlgK）增加2.40%~5.60%,HA的缩合度（C/H）降低3.51%~11.81%,（O+S）/C增加1.51%~8.74%。总体来看,施入生物质炭均能相对增加腐殖质各组分含量,降低C/H,提高HA的氧化度[（O+S）/C],且纤维类原料（玉米秸秆）生物质炭的效果更明显。纤维类原料（玉米秸秆）生物质炭显著提高了稳定性较高的土壤胡敏素碳比例（HM/SOC）,但降低了土壤HA的稳定性[HA的C/H降低,（O+S）/C增加];木质类原料（紫茎泽兰）生物质炭显著降低土壤胡敏酸碳比例（HA/SOC）和富里酸碳比例（FA/SOC）,对HM/SOC增加效益不显著,反之提高了土壤易分解有机碳比例。