东北典型黑土耕层颗粒组成与腐殖质层厚度的关系

土壤颗粒组成是影响土壤肥力的主要物理性质之一.为了了解东北黑土腐殖质层厚度与土壤颗粒组成的关系,通过在东北典型黑土区选择典型坡面,调查不同地貌部位土壤腐殖质层厚度,测定耕层土壤的颗粒组成,分析腐殖质层厚度和耕层土壤颗粒组成随地貌部位的变化趋势,以及土壤颗粒组成与腐殖质层厚度的关系.结果表明:土壤腐殖质层厚度由上坡至坡脚...     

Using soil survey information to characterize the soil-water state*

Uses of soil for a wide variety of purposes are largely governed by interactions between soils and climatic conditions. The soil-water state at any given moment depends on the hydraulic properties of the soil horizons, the weather and soil drainage. Emphasis in this presentation is on the manner in which the soil-water state is being characterized in the context of land evaluation. Land evaluation is concerned with the assessment of land performance when used for specified purposes (FAO, 1976). Current and future developments in land evaluation are discussed, emphasizing the particular input of soil survey when using computer simulation models for the soil-water regime. The soil-water regime plays a key role in land evaluation, as it governs the soil-water state at any given time during the year.     

基于电磁感应仪的黄河三角洲地区土壤盐分时空变异特征

针对黄河下游三角洲土壤盐渍化的空间复杂性与发生反复性,运用磁感式大地电导率仪EM38及其移动测定系统,结合GIS与地统计学方法,对该地区典型地块两个关键季节土壤盐分的时空变异特征进行了分析.结果表明,土壤表观电导率与盐分呈极显著相关性;各时段土壤盐分都表现出多层次空间结构的复合尺度效应,且短程变异构成了土壤盐分空间异质性的最主要部分;土地利用方式差异使得秋季时段土壤盐分呈弱各向异性,地形因素导致春季时段土壤盐分各向异性比在全步长域波动,但在整个研究尺度上仍为各向同性.空间分析表明,结构性因素主导了土壤盐分空间分布格局,随机性因素是加快该分布格局形成的重要因素;春季时段研究区总体表现出积盐趋势,且盐分变动幅度主要集中在10.0g/kg范围内.电磁感应仪与GIS的结合运用为不同尺度土壤调查与质量评价提供了新的途径,并为农业水土资源的决策管理提供指导.     

Using simulation to define moisture availability and trafficability for a heavy clay soil in the Netherlands

Computer simulation was used in assessing moisture availability and trafficabillity of a heavy clay soil in grass. Calculations were made of the soil-moisture regime over a period of 30 years using measured meteorological and water-table data. Soil-physical input data consisted of moisture-retention and hydraulic-conductivity data, which were determined on large, undisturbed soil columns. The effect of vertical and horizontal soil cracks was assessed by independent quantitative measurements. Results of the calculations were expressed in terms of the probability of occurrence of: (1) precipitation deficits, (2) moisture deficits considering the calculated soil-moisture regime, and (3) adequate trafficability. Results referred to successive 10-day periods during the year. The magnitude of the moisture deficit was also expressed in terms of its yearly probability. Simulation models are essential tools for a flexible characterization of land qualities in terms of probability estimates which are useful for planning purposes.     

Determining the depth of mixing layer in which soil solute releasing from soil to surface runoff on the unsaturated loess slope under artificial rainfall condition

Journal of Soils and Sediments - The mixing zone depth is a critical parameter in many popular agricultural non-point source pollution (NPS) models. Its variation for some special soil conditions...     

黄瓜果实苦味(Bt)基因的插入缺失(Indel)标记

为了筛选与黄瓜果实苦味(Bt)基因紧密连锁的插入缺失(Indel)标记,本研究以黄瓜(Cucumis sativusL.)果实苦味和果实不苦的高代纯合自交系46GBt和931为亲本构建的F2分离群体为试材,明确了黄瓜果实苦味性状遗传是符合单显性基因控制的质量性状.同时在完成Bt基因初步定位和双亲重测序的基础上,利用生物信息学分析双亲在初步定位区域的序列差异,设计了7对InDel标记.通过对含有184个单株的F2群体分析,获得了与Bt基因连锁距离为0.8 cM的Indel标记Bt-InDel-1.利用不同于本研究且包含58个单株的黄瓜F2群体材料对Bt-InDel-1的验证分析表明,该标记检测的正确率达到94.8％.本研究结果可用于无苦味黄瓜的分子标记辅助选择(MAS)育种及Bt基因精细定位.     

Using landscape and depth gradients to decouple the impact of correlated environmental variables on soil microbial community composition

Simultaneously assessing shifts in microbial community composition along landscape and depth gradients allows us to decouple correlations among environmental variables, thus revealing underlying controls on microbial community composition. We examined how soil microbial community composition changed with depth and along a successional gradient of native prairie restoration. We predicted that carbon would be the primary control on both microbial biomass and community composition, and that deeper, low-carbon soils would be more similar to low-carbon agricultural soils than to high carbon remnant prairie soils. Soil microbial community composition was characterized using phospholipid fatty acid (PLFA) analysis, and explicitly linked to environmental data using structural equations modeling (SEM). We found that total microbial biomass declined strongly with depth, and increased with restoration age, and that changes in microbial biomass were largely attributable to changes in soil C and/or N concentrations, together with both direct and indirect impacts of root biomass and magnesium. Community composition also shifted with depth and age: the relative abundance of sulfate-reducing bacteria increased with both depth and restoration age, while gram-negative bacteria declined with depth and age. In contrast to prediction, deeper, low-C soils were more similar to high-C remnant prairie soils than to low-C agricultural soils, suggesting that carbon is not the primary control on soil microbial community composition. Instead, the effects of depth and restoration age on microbial community composition were mediated via changes in available phosphorus, exchangeable calcium, and soil water, together with a large undetermined effect of depth. Only by examining soil microbial community composition shifts across sites and down the soil column simultaneously were we able to tease apart the impact of these correlates environmental variables.     

Fine silt and clay mineralogical changes of a soil chronosequence in the Langtang valley (Central Nepal)

Chemical and mineralogical properties of a soil chronosequence in the high mountain zone between 3857 m and 4120 m a.s.l. in Central Nepal (Langtang valley) are presented. The soils have been developed in moraine deposits which consist of acid gneisses. They were classified as Entisols, and Spodosols. XRD analyses of the clay and fine silt fraction show increasing changes with distance from the recent Lirung glacier, depending on the time of deposition, resp. soil age. Alteration of illite to interstratified minerals and to hydroxy-Al interlayered minerals or pedogenic chlorite with increasing soil development could be observed. The interstratified minerals could be identified as random and regular illite-interlayered vermiculite mixed-layer minerals. Intensification of the X-ray signals of the fine silt fraction is given compared to the clay. With increasing soil development differences between the clay and fine silt fraction seem to increase. Indications are given of interstratification of the mica-pedogenic chlorite and chloriteinterlayered vermiculite type in the more intensively weathered soils.     

Mineralogies of silt and clay fractions of twelve soil profiles in the Bolivian Andes (Callavaya Region)

Mineralogies of a soil catena in the Pampa of Ulla Ulla (4,300–4,600 m) and the soils of the steep slopes of the Cordillera de las Muñecas (“steep area”) were investigated. The latter area includes three altitudinal zones: herbaceous zone (3,900–4,800 m), shrub zone (2,700–3,900 m), and mountain forest zone (up to 2,700/2,800 m). The soils were classified according to Soil Taxonomy as Entisols, Mollisols, and Inceptisols. They were mainly derived from quartzitic schists and slope debris. Each horizon of each profile was representatively sampled for analyses.Muscovites and illites were the dominant minerals in the fine silt and clay fraction, respectively. Besides kaolinite, pyrophyllite and vermiculite, regular illite/vermiculite mixed layers, chlorite, feldspar and quartz were detected in both fractions. In a Typic Cryaquent from the Pampa of Ulla Ulla, smectites had been formed. Pyrophyllite, illite/vermiculite mixed layers and chlorite seemed to be unstable under acid conditions in most of these soils.     

Morphological and chemical properties of the meadow-semidesert soil complexes of the Khaki playa (the Caspian Lowland) and the influence of the biogenic factor on them

The initial stage of the development of the complex soil cover pattern in the Caspian Lowland was studied. The obtained data made it possible to reveal the specific features of the morphological and chemical properties of the soils on terraces of the Khaki playa and the role of burrowing animals in the formation of the microtopography and complex soil cover patterns on the youngest surfaces. The soil cover of the studied area consists of three-component complexes: light-humus quasi-gley solonetzes on relatively flat background surfaces, zooturbated solonetzes on microhighs, and humus quasi-gley soils in microlows. The layered deposits of the Khaki playa terraces and the shallow depth of the saline groundwater are responsible for the specificity of the modern salinization of the studied solonetzes. The distribution of the salts in their profiles has a sawshaped patter, which is related to the nonuniform texture of the deposits. On the microhighs composed of the earth extracted from 5- to 7-year-old suslik burrows, specific zooturbated solonetzes are formed. The known age of these formations makes it possible to determine the rate of the desalinization of the gypsum- and salt-bearing material extracted onto the soil surface and the rate of the salt accumulation in the lower part of the solonetzic horizon and in the subsolonetzic horizons in comparison with the data on the solonetzes of the background flat surfaces. The specific features of the soils in the closed microlows suggest that these soils have a polygenetic origin. The features of the recent hydromorphism predetermine the specificity of their morphology.     

Macro-structure of the surface layer of a self-mulching clay in relation to cereal stubble management

The macro-structure of the surface layer of a self-mulching clay was quantified statistically using methods described previously by the senior author. Soil macro-structures were determined at the 10, 20 and 40 mm depths in the 34th year of a long-term trial with two methods of cereal stubble management (burning and incorporation) and in the 1st year of a new trial with two methods of cereal stubble management (burning and retention) and two methods of weed control (herbicide and blade or sweep plough). Stubble management had only small and probably insignificant effects on soil macro-structure but mechanical weed control had a significant positive effect on soil macro-structure as compared to chemical weed control.     

Using caesium-137 measurements to investigate soil erosion rates in western Istanbul (NW Turkey)

Buyukcekmece Reservoir, located in the western outskirts of Istanbul, is one of the major water resources of Istanbul, and supplies drinking water to about 4 million people. Erosion in the catchment of the reservoir is an important problem in terms of its longer-term sustainability for water supply. There is an urgent need to obtain reliable quantitative data regarding erosion and deposition rates within the catchment to assess the magnitude of the problem and to plan catchment management strategies. In the absence of existing data, attention has focussed on the potential for using ¹³⁷Cs measurements to provide retrospective estimates of medium-term soil erosion rates within the catchment over the past ca. 40 years. To date, the ¹³⁷Cs approach has not been used to document soil redistribution rates in Turkey and this contribution reports an attempt to confirm the viability of the approach and the results of a preliminary investigation of rates of soil loss from uncultivated areas within the catchment. The soil redistribution rates estimated using the profile distribution conversion model varied from − 16.11 (erosion) to 4.59 (deposition) t/ha/year.     

Novel polyclonal-monoclonal-based ELISA utilized to examine lupine (Lupinus species) content in food products

Sweet lupines are increasingly used in food production. Cause for concern has been expressed due to the increase in reported lupine-induced allergic incidents and the association between lupine and peanut allergies. In the current study, a polyclonal-monoclonal antibody-based sandwich ELISA for the detection of lupine proteins in foods was developed. The assay was sensitive to both native and processed proteins from Lupinus angustifolius and Lupinus albus and had a detection limit of 1 mug/g. Intra- and interassay coefficients of variation were <5 and <17%, respectively. A selection of 112 food samples, both with and without lupine declaration, was evaluated for their content of lupine. The data showed that the majority were in agreement with the respective labeling. However, some inconsistency was seen, typically in bread/rolls and soy flours.     

Using caesium-137 measurements to investigate soil erosion rates in western Istanbul (NW Turkey)

Buyukcekmece Reservoir, located in the western outskirts of Istanbul, is one of the major water resources of Istanbul, and supplies drinking water to about 4 million people. Erosion in the catchment of the reservoir is an important problem in terms of its longer-term sustainability for water supply. There is an urgent need to obtain reliable quantitative data regarding erosion and deposition rates within the catchment to assess the magnitude of the problem and to plan catchment management strategies. In the absence of existing data, attention has focussed on the potential for using ¹³⁷Cs measurements to provide retrospective estimates of medium-term soil erosion rates within the catchment over the past ca. 40 years. To date, the ¹³⁷Cs approach has not been used to document soil redistribution rates in Turkey and this contribution reports an attempt to confirm the viability of the approach and the results of a preliminary investigation of rates of soil loss from uncultivated areas within the catchment. The soil redistribution rates estimated using the profile distribution conversion model varied from − 16.11 (erosion) to 4.59 (deposition) t/ha/year.     

Nitrogen losses from the field: denitrification and leaching in intensive winter cereal production in relation to tillage method of a clay soil

Abstract. Losses of soil and fertilizer nitrogen by leaching and denitritication from a clay soil in southern England have been measured over four years. Nitrate losses in drainage water from direct-drilled land averaged 20–30 kg N ha 'a' with wide seasonal variation. Ploughing and conventional cultivations increased this loss. Denitritication from direct-drilled land averaged 5–10 kg N ha 'a' with wide seasonal variation. Ploughing and drainage both diminished denitritication losses but cultivation had the greater effect. These nitrogen losses occurred mainly in autumn and spring.
Nitrogen losses, in drainage water or by denitritication after spring fertilizer applications, were related to the rainfall in the 28 days following top dressing. Approximately 40 mm rain was needed to cause a loss of 10% of the nitrogen applied but in practice losses were quite variable.     

Using in situ solid phase microextraction (SPME) for depth profiling in sediments treated with activated carbon

Purpose

Sediment contamination in US waterways is an expensive and complicated issue, and as acceptance of nontraditional sediment remediation strategies broadens, novel and efficient methods to assess and monitor the bioavailability of hydrophobic organic contaminants (HOCs) in contaminated sediments will play an important role.

Materials and methods

In this project, solid phase microextraction (SPME) fibers inside perforated steel tubes were used as in situ passive samplers to measure polycyclic aromatic hydrocarbon (PAH) concentrations in sediment before and after treatment with activated carbon (AC). Two modes of waterjet amendment injection were used to apply the AC. In the first treatment, a single 2-min injection was shot into the center of a test vessel, and in the second treatment, multiple 7-s injections in a grid were placed in sediment.

Results and discussion

In the single injection, no treatment was observed 5 cm away from the injection, while at 2.5 cm, >90 % decrease of PAH pore water concentration was observed, indicating a similar bioavailability decrease. In the multiple injection experiment, >90 % PAH pore water level reductions were observed throughout the test vessel. Highly contaminated and less contaminated sediments were mixed with 0–5 % AC by weight to develop AC treatment curves. Over 99 % reduction in PAH pore water concentrations and bioavailability was observed in the less contaminated sediment at 3 % AC, while 99 % reduction was never reached even at 5 % AC addition in the highly contaminated sediment. Different treatment curves were observed for the different contaminated sediments. In situ equilibration times were 120, 215, and 250 h for phenanthrene, pyrene, and benzo(a)anthracene, respectively.

Conclusions

The results show that in situ SPME is a viable method to observe AC treatment and evaluate reductions in pore water concentrations and bioavailability.     

Diffusion of N-labelled N2O into soil columns: a promising method to examine the fate of N2O in subsoils

Nitrous oxide research has generally focused directly on measuring fluxes of N₂O from the soil surface. The fate of N₂O in the subsoil has often been placed in the ‘too hard’ basket. However, determining the production, fate and movement of N₂O in the subsoil is vital in fully understanding the sources of surface fluxes and in compiling accurate inventories for N₂O emissions. The aim of this study was to generate and introduce into soil columns ¹⁵N labelled N₂O, and to try and determine the consumption of the ¹⁵N₂O and production of ambient N₂O. Columns, 100 cm long by 15 cm diameter, were repacked with sieved soil (sampled from 0 to 5 cm depth) and instrumented with silicone rubber gas sampling ports. Nitrous oxide enriched with ¹⁵N was generated using a thermal decomposition process at 300 °C and then transferred to 2 l flasks. After equilibrating with SF₆ tracer gas the ¹⁵N₂O was introduced into the soil columns via passive diffusion. Gas samples from the soil profile and headspace flux were taken over a 12-day period. A watering event was simulated to perturb the ¹⁵N₂O gas composition in the soil profile. Using the measured ¹⁵N enriched fluxes and the rate of decline in ¹⁵N in the N₂O reservoir, from which the N₂O diffused into the soil, we calculated an N₂O sink (consumption plus absorption by water) equal to 0.48 ng N₂O g⁻¹ soil h⁻¹. The decrease in the ¹⁵N enrichment between successive soil depths indicated N₂O production in the soil profile and we calculated a net N₂O production rate of 0.88 ng N₂O g⁻¹ soil h⁻¹. This pilot study demonstrated the potential for simultaneously measuring both N₂O consumption and production rates, using the ¹⁵N enrichment of the N₂O measured. Further potential refinements of the methodology are discussed.     

Application of a mobile electromagnetic sensing system (MESS) to assess cause and management of soil salinization in an irrigated cotton-growing field

Abstract. Generally, traditional soil surveys do not adequately account for the spatial variability of soil properties. Maps that are derived using these cursory soil data are likely to contain errors and thus make interpretation and soil management difficult. On the other hand quantitative methods of soil inventory at the field scale involve the design and adoption of sampling regimes and laboratory analysis that are time consuming and costly. In the latter case new technologies are required to efficiently sample and observe the soil in the field. This is particularly the case where soil salinization is prevalent, and detailed quantitative information for determining its cause is required. In this paper, a Mobile Electromagnetic Sensing System (MESS) is described and its application in an irrigated-cotton field, located in the lower Namoi valley in New South Wales, Australia. Results from the EM38 instrument were found to be correlated with the effective cation exchange capacity ( r ²= 0.81). This was related to variability in soil mineralogy across the field. In addition, differences in soil chemical and textural variables, measured along a transect and adjacent to water storage, were used to identify seepage areas near a water reservoir where soil salinization was evident.