Abstract:Fengqiu County is a typical alluvial plain area that lays the middle and lower of the Yellow River. Different texture layer type, thickness and its combination in soil profile, which are important factors affect soil water and fertilizer storage and supply capacity. Through the field survey of 39 soil profiles and 113 soil samples drilled to get the first hand data. Based on two basic features of layer texture types and their position in the profile to define characteristic texture layer, in the study area nine kinds of characteristic texture layers have been established. Nine kinds of characteristics texture layers combinations have been divided automatically by applying the fuzzy c-means algorithm model through taking the missing features and the thickness of the characteristic texture layers as the basis of data, which have been observed in the soil profile and soil drilled samples in the study area. Combined with statistical methods, it is to achieve the spatial distribution of nine typical soil texture combinations by the single category membership map and the maximum membership map. They revealed the combination characteristics of different texture layers in the vertical direction and the distribution of different texture profile configuration in the horizontal direction，which provided more objective and a wealth of basic information for regional land quality evaluation, and assessment of potential productivity, and improved utilization practice of soil.

Abstract:Rangtang County, Sichuan Province where the prevalence rate of Kaschin-Beck disease (KBD) is relatively high and hence was selected as a typical case in this study to explore distribution characteristics of soil elements and its relationship to KBD. Soil samples were collected from two soil layers (0 ~ 20 cm and 20 ~ 40 cm) in natural and cultivated fields, separately for analysis of mechanical composition and total concentrations of nine soil elements. Results show that the subsoil is higher than the topsoil in contents of Fe2O3, Co, Mn, Se, As and percentage of physical clay, but lower in contents of Cu, Hg, Mo, Zn and percentage of physical sand. As the local natural soils are less disturbed by human activities, no significant difference was found between different soil layers or soil profiles (p > 0.05). The distribution of Mo and Se elements in the soil led to poor crop uptake of the two elements, thus causing the local population, especially children, nutritional deficiency in Se and Mo, which is demonstrated to be closely related to KBD. Affected by the parent materials and pedogenesis of the soils, Fe2O3, Co and Mn similar in physical and chemical properties, as well as Zn, Cu and Hg all showed a better positive correlation (p < 0.01). However, no significant correlation was observed between these elements and the clinical prevalence of Kaschin-Beck disease. A total of 23 administrative villages involved in this study were divided into four groups by an ascending sequence in terms of clinical prevalence of Kaschin-Beck disease, i.e. Group I (n=6, incidence rate 14.02% ~ 19.87%), Group II (n=6, incidence rate 24.62% ~ 28.20%), Group III (n=6, incidence rate 28.45 % ~ 36.26 %) and Group IV (n=5 incidence rate 37.30 % ~ 53.66 %). Due to the adsorption of Se by soil clay and Fe2O3, which are similar in distribution characteristics, the disease is getting more severe with decreasing soil clay and Se content in the soil. The distribution of Hg in soil was just contrary to that of Se. However, no evidence is confirmed that antagonism exists between Se and Hg in soil low in both.

Abstract:Quality evaluation of cultivated land is important to guidance of agricultural production. Whether the evaluation method is appropriate or not directly affects reliability of evaluation results. Through practical investigation, collection and analysis of samples, attribute data of 249 surface soil samples and rice yield data of 95 paddy fields were obtained in the study area of Yujiang County, Jiangxi Province. Norm value method and the newly established Bio-Norm method were used separately to determine indicators for evaluation of cultivated land quality and their weights and membership functions as well, which were then used to evaluate cultivated land quality of paddy fields in the study area. Comparison between Bio-Norm method and Norm value method shows that the indicators selected with the Bio-Norm method were more representative than those done with the Norm value method; their weights better reflected importance of the indicators; and the thresholds of their membership functions better reflected the actual requirements of rice growth. Evaluation results show that regression coefficient of determination (R2) between cultivated land quality index(IFI value) obtained with the Bio-Norm method and rice yield was way higher than that with the Norm value method, and the distribution of values obtained with the Bio-Norm method tallied better with the distribution of rice yield grades in the region. Therefore, the Bio-Norm method is more scientific and reasonable than the Norm value method in evaluating cultivated land quality.

Abstract:It is of great practice significance to define baselines for soil heavy metals in the Yangtze River Delta Region to evaluation of status quo of the heavy metal accumulation in the soil. In the presence of anthropogenic heavy metal pollution, soil heavy metal data always significantly deviate from normal or lognormal distribution, which affects reliability of the results of classical statistics. In contrast, robust statistics is aimed at lowering the effect of outliers on statistical analysis. With the robust regression method regression relationships between Cu and Pb concentrations in topsoil and in subsoil were established for the study region of Zhangjiagang, which has thousands of years of agricultural history and has recently been developing rapidly in industry. Based on the topsoil Cu and Pb concentration baselines calculated through robust regression of their subsoil concentrations, the status of soil Cu and Pb accumulations were evaluated. Results show that the calculated geochemical baselines can reflect natural variation of soil Cu and Pb background values between different sampling sites. Compared with the robust statistical method, the evaluation of soil heavy metal accumulation in a region that has spatial variation of natural background values on the basis of the national standard for soil environmental quality or regional soil background values would generate bigger errors.

Abstract:The study of characteristics of soil bidirectional reflection is not only essential to inversion of land surface temperature and albedo, but also of great significance to the development of quantitative remote sensing and soil remote sensing technology per se, and the characteristics are the background factors that must be taken into account in the study on remote sensing of global land-cover The directional distribution of soil reflectance contains information on structure, particle size distribution and roughness of the surface soil and potentially some additional information on soil composition, e.g. soil water and organic matter content. Based on indoor measurement of bidirectional spectral reflectances of three different types of soils (i.e. red soil, paddy soil and coastal saline soil) different in moisture content, variation of the reflectance with observation angle in the visible light and near infrared bands was analyzed for law It was found that soil bidirectional reflectance increased with increasing observation zenith angle regardless of observation azimuth, because the shadow which is formed by soil grains obscuring each other in the field of view decreased as the observation angle increases. Soil bidirectional reflectance is azimuthally symmetric in the perpendicular plane, and the reflectance is the highest in the backscattering direction, because the shadow observed was the lowest due to the fact that the observer and the illuminator are in the same direction and most of the soil grains irradiate directly. Contrarily, the reflectance is the lowest in the forward scattering direction because of the increasing shadow in the field of view. Bidirectional reflectance of soils different in surface moisture content was simulated well with the Hapke’s model, which is derived from the radiative transfer theory. Moreover, inversion of the major parameters of the Hapke’s model was performed based on the measured soil bidirectional reflectances, and effect of soil moisture on the reflectance was studied. Results show that single scattering albedo（SSA）increases with the declining soil moisture, but is independent of the conditions at the time of observation. The findings of the study may be used a scientific basis for inversion of soil moisture content with the single scattering albedo.

Abstract:The use of soil dielectric properties as an indirect measurement of volumetric moisture content is accepted in a wide range of disciplines. Empirical relationship was studied between soil dielectric constant and volumetric water content in eight soils of four types, i.e.. fluvo-aquci soil, aeolian sandy soil, red soil, and paddy soil. Based on soil column experiments, the Topp’s equation (1980) was amended, and correction factors a and b of the Herkelrath (1991) equation were verified. Results show that the prediction of soil volumetric moisture content using the Topp’s equation was relatively big in error for sandy loam fluvo-aquci soil, silty clay fluvo-aquci soil, aeolian sandy soil, and clay red soil. Compared with thr Topp’s equation (1980), the Topp fitting equation was optimized, but its effect was not satisfactory with errors being still quite big in predicting volumetric moisture contents various in range, especially for clay red soil. The Herkelrath fitting equation was relatively better for all the four types of soils, and could be cited as the first priority choice for application. All the three relationship equations were quite good in predicting volumetric moisture content in the two paddy soils different in texture, with the mean absolute error being less than 0.03 cm³ cm^-3.

Abstract:In order to find a simple method fit for estimating soil water retention curves of paddy soils in the Taihu Lake region, thirteen physico-empirical methods were evaluated，based on measured basic soil properties and soil water retention curves. Results show that physico-empirical methods based on shape similarity were superior to most of the fractal methods in prediction effect, but inferior to the pore surface fractal model based on the Kravchenko- Zhang fractal dimension method and the Brooks-Corey soil moisture curve equation (shortened as KZBC model). The physico- empirical methods varied in accuracy of the precision of soil moisture content under different pressure heads. So in practice, it is necessary to take into account not only the applicability of a model, but also the scope of pressure head. The KZBC model is the highest in prediction accuracy and practicability and hence the best model in this study for estimating soil water retention curve of the paddy soils in Taihu Lake area.

Abstract:Based on the measurement of two hundred and eighty four soil samples taken in grid patterns of three different scales (with intervals of 50 m, 5 m and 0.5 m separately between sampling points) in a saline-alkaline field in Manasi County, Xinjiang, spatial patterns of soil water repellency and soil physical-chemical properties were analyzed by means of classical statistics, spatial autocorrelation theory, geostatistics and fractal theory. Results indicate that 1）both soil water repellency and pH followed a normal distribution while the other soil properties a lognormal distribution, and most of the soil properties studied varied to a moderate degree regardless of scales; 2）Moran’s I coefficients of all the soil properties were quite similar in variation, which ranged from -0.8 to 0.6 at all the three scales; 3）most semi-variance theoretical models of the soil properties could be fit with spherical models at all the three scales; and 4）within a certain range, the soil properties showed fractal features, and their fractal dimensions varied in the range from 1.75 to 1.96. The findings indicate that soil water repellency and soil physical-chemical properties are somewhat different in spatial distribution at different scales.

Abstract:Saturation-capillary pressure (S-p) relationships of consecutive drainage-imbibition cycles in an air-water two-phase sandy medium were measured for investigation of hysteresis between drainage and imbibition processes. Results show that the degree of hysteresis was obviously not related to the number of the drainage-imbibition cycles, and it decreased with increasing the initial water saturation of the imbibition process in the drainage-imbibition cycle. The S-p relations measured in the tests were fitted with the Van Genuchten (VG) model and parameters of the VG model were analyzed. Results also show that parameter α related to the entry pressure approximated to a constant in all the drainage processes. Both the measured S-p relations and the parameter α indicate that the entry pressure of a medium is a constant, independent from the effects of path and initial water saturation of the drainage process. In the imbibition processes, the parameter α decreased with increasing initial water saturation, which corresponds positively to the change in hysteresis. The VG model is applicable to the description not only of simple S-p relations, but also of S-p relations under complicated drainage-imbibition cycles.

Abstract:Using conventional qualitative and quantitative analysis methods, water content and composition and content of soluble salts at different positions in a simulated archeological site in the Shaanxi Normal University were determined. Results show that calcium sulfate and sodium sulfate were the mainly soluble salts, and moved vertically and horizontally along with soil water towards the surface of the site and finally accumulated in the surface soil. The destructive effect of soluble salts on soil structure of the site was analyzed with the aid of XRD, SEM and 3DSDDM. It was found that as a result of the accumulation in the surface soil, soluble salts formed a huge stress in soil pores, thus reducing the cohesion between soil particles, widening the distance between them, and eventually making the surface soil white and loose. When worse comes to the worst, the soil got too loose and broke off. The findings in this research can be used as scientific basis for control of salt damage to the site and are of great theoretical studies and practical to the protection of archeological sites and historic relics.

Abstract:The study was designed to study spatial variation of soil pH, electrical conductivity, soil organic carbon, total nitrogen, available nitrogen, total phosphorus and available phosphorus, and scale characteristics of spatial heterogeneity of the soil chemical properties at various scales, such as rhizosphere, individual, population, topography and region, separately in the Gurbantunggut Desert, with the purpose of finding out at which scale the heterogeneity was the greatest and its dominating factor. Results show that soil pH demonstrating an order of individual > population > topography > region > rhizosphere, which indicated that the variation of soil pH in the desert ecosystem was dominated by the biotic progress of plant individual and population. The effects of topography, climate and hydraulics were very limited, and the effect of rhizosphere was the least. In terms of electrical conductivity, the scales followed the order of individual > region > population > topography > rhizosphere, which demonstrated that an individual of shrub played a dominating role in variation of soil salt around the taproot. For soil organic carbon, total nitrogen, available nitrogen and available phosphorus, the highest heterogeneity also existed at the individual scale, which was followed by the topography scale, and the least did at the population scale, which suggested shrub individuals were the factor dominating soil nutrients, topography was the next, and population was the least. For soil total phosphorus, heterogeneity was the highest at the scale of topography and the smallest at the scale of rhizosphere, indicating topography and plant individual were the major factors affecting heterogeneity of soil total phosphorus, and the rhizosphere was the least.

Abstract:Contamination of phthalate esters (PAEs) in agricultural soils is reported frequently in China recently and has raised wide concern to researches due to the effects of endocrine disrupt. Ultrasonic extraction and Soxhlet extraction were both performed to extract the added PAEs from soil. The results indicated that the ultrasonic extraction was more feasible to be the pretreatment method for PAEs analysis of soil sample as a result of increasing recovery and decreasing procedure blank. Meanwhile, operating procedures of ultrasonic extraction were studied further, Preservation of 1-2ml of the extract instead of dryness will effectively prevent the loss of compounds from volatilization in the process of rotating evaporator. No obvious difference was observed between the treatment of cleanup and without cleanup by florisil when analyzed by GC-MS in present study. Skip of the cleanup process will increase the efficiency of PAEs analysis, however, the interference of pigment or other components in the soil samples will have an impact on the accuracy of Bis(2-ethylhexyl) phthalate (DEHP) and other target compouds.

Abstract:Comparison of lab-prepared goethite-kaolinite association with goethite-kaolinite mixture as control was done for analysis of its microstructure and mechanism of its formation. It was found that in the association kaolinite was well wrapped by goethite, but in the mixture they coated neither. Compared to pure goethite or kaolinite, neither goethite or kaolinite in the association showed much change in the distance between major crystal planes; but the association showed a higher micropore volume and a lower average pore diameter. However, both pore parameters of the mixture were close to the average values of monomeric goethite and kaolinite. The surface fractal dimension D of the mixture and the association increased, and Dmixture was higher than Dassociation. Infrared spectra (IR) demonstrated that the vibration frequency of ≡Fe–OH increased and that of ≡Al–OH, Al–O, Si–O and Fe–O decreased in the dyads. The magic angle spinning nuclear magnetic resonance spectroscopy (MAS NMR) showed that the cementation between goethite and kaolinite led to increased chemical shift of 29Si and 27Al towards positivity, which implied that cation exchange between ≡Fe_nOH₂^n/2)+(n = 1, 2, 3) and ≡Si–OH or ≡Al–-OH^0.5-, and anion exchange between ≡Fe–OH and ≡Si–O- or ≡Al–OH^0.5-, surface coordination between O atoms on the surface of kaolinite and Fe atoms on the surface of goethite were the main mechanisms of cementation between goethite and kaolinite, where hydrogen bond and electrostatic attraction served as the main acting forces. Although the IR and NMR parameters of the association and mixture displayed similar changes, the variation of the former was more significant, indicating that the cementation strength between goethite and kaolinite in the association is greater than in the mixture.

Abstract:Based on surface thermodynamics and XDLVO theory, free energy changes induced by hydrophobic interactions (GH), free energy changes originated from electrostatic force (GEL) and the total free energy changes in the adsorption of P. putida and B. subtilis on kaolinite and montmorillonite were obtained. The negative values of GH and the positive values of GEL suggested that the hydrophobic force favors, and the electrostatic force unfavors the bacterial adsorption on kaolinite and montmorillonite. The absolute values of GH were much larger than those of GEL, indicating that hydrophobic interactions play a role more important than electrostatic force does in bacterial adsorption. The negative total free energy changes (G) suggested that the sorption of bacteria on clay minerals is a thermodynamically spontaneous process. Greater G values for bacterial adsorption on kaolinite than on montmorillonite indicated higher affinity of the bacteria for kaolinite than for montmorillonite.

Abstract:Soil samples were collected from croplands and vegetable lands in Quzhou County of Hebei, Shouguang County of Shandong and Shunyi District of Beijing for comparison between lands under two different patterns of land use at the same location in content, distribution in the soil profile and composition of DOC. Results show that in the topsoil soil organic carbon (SOC) was 3.16 ~ 47.4% higher and total Nitrogen (TN) 3.09 ~ 64.1% higher in the vegetable fields than in the crop fields, while soil C/N and pH lower. The DOC content in either crop or vegetable fields decreased significantly with soil depth. The mean of the DOC contents in the topsoils of the vegetable fields was 1.70 times as high as that of crop fields. A significantly positive relationship was observed between SOC and DOC. In terms of composition of the DOC, its fractions followed an order of Hydrophilic matter (HIM) > Hydrophobic acids (HOA) > Hydrophobic neutrals (HON) > Hydrophobic bases (HOB) in the top soil (0~30 cm) in both crop fields and vegetable fields. In vegetable fields, HOA accounted for 19.0~26.7%, while in crop fields for 14.83~16.42%; The difference between the two fields in Shouguang was quite significant (p<0.05), which is probably related to the higher SOC contents and lower pH in its vegetable field. The HOM/HIM ratio was 0.30, 0.39 and 0.41 in the vegetable fields of the three regions, which may suggest that the vegetable fields vary in humification degree. In conclusion, transformation of crop fields into vegetable field significantly affects quantity and quality of DOC.

Abstract:Soil samples were collected from Sankou, Taihuyuan (Xitianmu village) and, Hengfan towns, the main production area of Phyllostachys praecox stands in Lin`an, Zhejiang province where covered of 3.5•104 hm2 area. Soil profiles were excavated in 1 a, 5 a, 10 a, 15 a planting years of bamboo stands and each with 4 sites replications to study the variation of soil phosphorus content and distribution in due time of intensive management practices by yearly heavy fertilization and 30 cm thick organic mulch in winter season for higher yield and quality of Bamboo shoots. Soil P component was analysed by solution 31P NMR (AVANCE II 300MHZ BRUKER Co.) to give a sight of dynamics of various phosphorus components and its possible impact to soil and water environmental quality. Results indicated that, with the prolong of intensive management years of Phyllostachys praecox stands, the contents of soil total phosphorus (TP), available phosphorus (AP) increased steadily up to P 1.96~2.01 g kg-1 and P 458~468 mg kg-1, respectively. However, the increase of soil organic phosphorus (SOP) was relatively small. But all of the TP, AP, SOP contents showed gradually decrease from top layer > middle layer >> bottom layer in a soil profile which revealed that the soil phosphorus was enriched on the surface layer. The ratio of SOP to TP is relatively low as only 29%~20% and showed that it was gradually going down as the planting year prolonged. Data from the solution 31P NMR analysis revealed that inorganic orthophosphate was represented a significant proportion of the total P content, and the content of orthophosphate monoesters were lower but they increased with the planting years prolong. While contents of those orthophosphate diesters and pyrophosphate esters were a little, which revealed that the increase of SOP was quite low during the period of studied Phyllostachys praecox stands. Due to the high soil available P in Phyllostachys praecox stands of studied area, we suggested that any further P fertilizer application should be stoped immediately till to the AP lower down to resonable level , soils have accumulated enough P for high yield and quality bamboo shoots production of next 3～5 years , it is not only save the valuable resources of P but also benefit in reduce the potential risk to soil and water pollution.

Abstract:This study was conducted in Larix principis-rupprechtii forests, located in GuanDi Mountain, Shanxi Province, China. Two plots（32 m×32 m） were selected which represented disturbed stand(plot A) and undisturbed(plot B) respectively. Based on theory and methodology of spatial pattern analysis in geostatistics, samples were taken at three soil depths (0~10 cm, 10~20 cm and 20~30 cm.) using soil core (7.0 cm in diameter) . The spatial heterogeneity of soil characteristics (soil moisture , pH ,total N )was analyzed. The result showed that soil moisture and its spatial heterogeneity decreased in disturbed stand, remained mainly spatial variation at small scales. Harvesting increased the means of soil pH (pH =6.86,plot A).Compared with soil pH at same soil depth in different stand, the proportion of randomly variation increased in disturbed stand and spatial autocorrelation variation became weaker. After cutting disturbance, the soil total nitrogen decreased significantly. Semivariogram analysis demonstrated that harvesting modified spatial pattern of soil total nitrogen , the spatial heterogeneity decreased at large scales.The spatial heterogeneity intensity of soil moisture, pH and total nitrogen became lower along with increase of soil depths.

Abstract:It is more efficient to use crop simulation models to evaluate alternative ways to improve agroecosytem performance than experiments only of the biophysical system. A key evaluation process prior to a model’s application is its sensitivity of yield and soil nutrients to input parameters because effects of parameters under one condition may not have the same sensitivity in other location. The purpose of this study was to evaluate and test the sensitivity of the DSSAT v4.5 to changes in agricultural management parameters. Maize (Zea mays L.) growth, development and yield was simulated using the DSSAT model in conjunction with a field experiment that was conducted in Northeastern China on a black soil (Mollisols). The cultivar coefficients were obtained using field data and then the sensitivity of the simulated LAI, aboveground biomass and yield to various input parameters was examined. Sowing 8 to 10 days earlier resulted in maize yield reductions of 10%. Yields increased curve-linearly with the increases in plant density in the low to mid range (< 5 plants m^-2), and levelled off when the density reached 5 plants m^-2. Fertilizer N rate followed a diminishing yield pattern with the maximum yield being obtained at a fertilizer N rate of N 200~240 kg hm^-2. The best fertilizer N application date was 15 – 23 June. This work confirmed that DSSAT model could be a useful simulation tool to be used for simulating maize growth under other regions of China and sensitivity method established in this research could be used for other crops, such as rice and wheat. Sensitivity analysis of soil C and N in response to crop managements is required in future study.

Abstract:Three controled release fertilizers, the ration of N-P2O5-K2O which were 14.25-14.25-14.25、13.5-13.5-13.5 and 12.75-12.75-12.75, coated with fly ash and organic agglomerant, were made of common compound fertilizer (N-P2O5-K2O：15-15-15). A field experiment was conducted to study the effect of coated release fertilizers on physiological characteristics, yield and quality of Chinese cabbage. The result showed that the coated release fertilizers could increase the leaf chlorophyll content, photosynthetic rate , transpiration rate and stome conductance and decrease the leaf stomata limitation at same fertilizer level. Comparing to common compound fertilizer, the coated release fertilizers increased the plant height 0.13-1.00cm, diameter 0.01-2.26cm, length 0.77-1.90cm, wide -0.63-3.47cm. At the same time,. the coated fertilizers improved the per plant weight of Chinese cabbage 10.1%-33.3%.In addition, the coated release fertilizers decreased the NO3--N, organic acid contents, and improved the soluble sugar, sugar-acid ratio and Vc contents of the leaf at the harvest stage.

Abstract:Through inoculation of isoproturon-degrading bacteria into soils different in environmental conditions, characteristics of the degradation of isoproturon in the soils by strains Sphingobium sp. YBL1, YBL2 and YBL3 were studied, and effects of soil type, temperature, soil moisture, inoculation dosage and carbon/nitrogen source on the degradation were analyzed. It was found that strains YBL1, YBL2 and YBL3 could efficiently degrade isoproturon (>80%) in Magan soil (pH 6.7), but could not in Red soil within 24 hours. The degradation rates of isoproturon in Magan soil by these three strains were positively related to soil moisture (10%~40%) and temperature (16~37°C). When the dosage of inoculation was less than 10⁵ CFU per gram soil all these three strains were unable to degrade isoproturon in soil in 24 hours after incubation. Supplementation of glucose could enhance degradation of isoproturon in Magan soil by these strains, while the addition of NH₄NO₃ could do reversely.

Abstract:Characteristics of pyrethriod-degrading strain Sphingobium sp. JZ-1 and its crude enzyme extract degrading pyrethriod were investigated in this experiment. The strain was capable of degrading a wide range of pyrethroid pesticides, which followed a descending order of permethrin > fenpropathrin ≈ cypermethrin > cyhalothrin > fenvalerate > deltamethrin > bifenthrin in degradation rate. No chiral selectivity was observed in biodegrading pyrethroid isomers. The initial reaction of Sphingobium sp. JZ-1, in degrading cypermethrin was to break carboxylic acid ester bonds under the catalysis of permethrin hydrolase yielding equimolar amounts of dichloroving acid (DCVA) and 3-phenoxybenzaldehyde, which was then oxidized into phenoxybenzoic acid. The pyrethroid hydrolase in Sphingobium sp. JZ-1 was expressed without pyrethroid induction.

Abstract:Characteristics of coleopterans in soil at different stages of vegetation succession of Leymus chinensis grassland were studied in Jilin Province in June, August and October of 2007. A total of 1 670 soil coleopteran individuals were captured and fell into 19 families, among which Carabidae, Staphylinidae, Curculionidae larvae were dominant, and especially the latter were found almost everywhere. Significant differences were found in number of individuals and groups of soil coleopterans between the stages. The vertical distribution of soil coleopterans was characterized by gathering in the surface soil. Diversity index(H′) of the soil coleopterans varied from stage to stage, showing an order of Leymus chinensis community > Leymus chinensis + Chloris virgata community > Chloris virgata community > Suaeda salsa community, which was closely related to the process of vegetation succession. Seasonal changes were quite obvious in individual number, group number and diversity index(H′) of the soil coleopterans and the number of individuals peaked in August, except for the stage of Chloris virgata community. Grey correlation analysis revealed that soil water content, soil pH and soil organic matter are factors significantly affecting soil coleopterans.

Abstract:Effect of planting legume crops and inoculation of Plant Growth Promoting Rhizobacteria (PGPR) and legumes on soil building in newly-reclaimed land was studied with a field experiment laid out in a newly-reclaimed slopeland in Beibei, Chongqing, China. The experiment field was divided into several plots, which were all planted with alfalfa, but inoculated separately with nil, rhizobia or rhizobia + other PGPR (including associative azotobacters, P-releasing bacteria, and K-releasing bacteria). Results show that the incubation of rhizobium and PGPR in combination significantly increased organic matter, total N, total P and total K, available P and available K in the soil, by 33.5%, 22.7%, 3.8%, 11.5%, 11.4% and 22.3%, respectively, over the incubation of rhizobia alone and by 42.2%, 58.8%, 8%, 12.6%, 37.2% and 40.2%, respectively, over the treatment of no incubation. Furthermore, the treatment of rhizobium + PGPR also significantly increased the nodule weight, plant height, fresh root weight, fresh aboveground biomass and plant’s total nitrogen by 44.5%, 33.2%, 77.3%, 76.7% and 17.7% respectively over the treatment of rhizobia. It is obvious that plant alfalfa in combination of incubation of proper PGPR has a much better effect on soil building, thus accelerating the process of ameliorating newly-reclaimed poor land.

Abstract:Soil aggregates and soil organic matter are inseparable because they are the basic substances that maintain soil structure and fertility. The former is the place where the latter exists, whereas the latter is the cement that keep the former in existence. In the current literature, more reports are available on soil aggregates and soil organic matter, separately than on characteristics of soil organic matter in soil aggregates. This paper is going to present an introduction, from the perspective of physical fractionation combined with chemical fractionation of soil organic matter, to advancements both at home and abroad in researches on quantity and properties of soil organic matter in soil aggregates and their responses to agricultural measures, including fractionation of soil aggregates, quantity and stability of each fraction, quantity of organic matter in aggregates, properties of the unfractionated organic matter and properties of the humus fraction, quantity and properties of the organic matter in each particle-size fraction, quantity and properties of the organic matter in fractions sorted by aggregate-density in combination, impacts of land-use pattern and long-term cultivation and fertilization on organic matter, etc. in order to promote the research on interactions between soil aggregates of different particle sizes and different humic fractions and their contribution to soil carbon fixation and soil fertility, to explore relationship between the physical protection and chemical protection of soil organic matter and provide a basis for exposing mechanisms of soil carbon sequestration and build-up of soil fertility.

Abstract:Soil chronosequences are valuable tools for investigating rates and directions of soil evolution and their modeling as well as for testing theories of pedogenesis. To obtain reliable results, the establishment of soil chronosequences must consist of two critical processes, i.e. quantitative identification of parent material uniformity or lithologic discontinuities (LDs) between and within profiles of the chronosequence, and identification of age of the soils with numerical or geochronometric dating methods and surface exposure (relative) dating methods. In this paper, types and constructing procedures of soil chronosequences, and in detail, the detection methods of parent material uniformity or LDs as well as age dating techniques are reviewed, with a view to providing detailed references for correct construction of soil chronosequences and better understanding the effects of the time factor on soil development. In addition, this paper discusses the significance of the chronosequence approach in pedogenesis research.

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