Abstract:Based on the measured δ¹⁸O in soil water and precipitat ion in the middle of the Tibetan Plateau in the summer of 1998, relationship between δ¹⁸O in soil water and soil water movement is discussed in this paper.The results show that δ¹⁸O in soil water in the upper layer is affected directly by δ¹⁸O in precipitation, and both vary in the same trend, whereas δ¹⁸O in the underground water is not much affected by δ¹⁸O in precipitation directly, and it varies slightly.This indicates that the underground water there is not replenished from precipitat ion in the current summer, but from accumulation of severa-l years precipitation.The variation of δ¹⁸O in different layers of the profile soil reflects the movement of precipitation water from surface towards bottom in the soil.The impact of precipitation on δ¹⁸O in soil water is obvious only in the water of the upper soil layer, while the underground water has more impact on δ¹⁸O in soil water of the lower layer, showing the important role of ground water in soil water movement.

Abstract:The soil erodibility (K) value in this region was investigated with the formula calculation method, based on the physical and chemical properties of soil and soil map of the soil survey.In this study, a K value map well registered with the topographic map was made, in which accurate geographic positions could be located.Meanwhile, applications of the K value map in soil and water conservation, monitoring of soil loss, ecological agricultural construction and reducing floods were also discussed.

Abstract:Sustainable land use is an important guarantee of sustainable development.Land suitability assessment of the Shizi Mountain area in Wuhan City was carried out by using Geographical Information System technology and the neural network model in 1982, 1994 and 1998 separately.Results showed that land most suitable for vegetable was small, above eighty percent of the area was land suitable or less suitable for vegetable and this percentage showed an increasing trend in area.Land suitable for vegetable increased by 29.12hm², occupying 66.72 percents, while the land less suitable for vegetable dropped by 62.52hm², down to 21.85%.From 1982 to 1994 and from 1994 to 1998, land the most suitable for orchard decreased by 246.78hm², an over fifty percent drop.Land suitable for orchard increased by 137.31hm².48.42hm² of land less suitable for orchard emerged in 1998.After the vegetable plot distribut ion map and orchard distribution map was overlaid on their suitability evaluat ion map, respectively, through MAPGIS software, results showed that, in vegetable plot area, the most suitable area increased by 5.99 hm².Suitable area increased by 15.58hm² and less suitable area by 17.47hm², but their ratio dropped by over thirty percent, and in orchard area, the most suitable area decreased by 31.87hm², suitable area first increased then decreased sharply, it dropped by 22.42hm².Less suitable area increased by 45.90hm².

Abstract:In the present work, release of hydrogen ions during adsorption of copper ions by variable charge soils was studied.The results showed that there was an abrupt charge in pH on neutralization curve of H, Al-saturated variable charge soils, but no such an abrupt charge in pH could be observed when copperions were added into the suspension of variable charge soils.The two neutralization curves of variable charge soils with and without the addition of copper ions coincided each other when the pH of soil suspension was lower than a certain value, and separated obviously when the pH was higher than that value.It is suggested that no hydrogen ions were released after the addition of copper ions when the pH of soil suspension was lower than a certain value.This pH value was related to the content of iron oxide.The larger the iron oxide content, the higher the pH value.For the majority of variable charge soils, this pH value was about 4.Kinetic studies on the release of hydrogenions during adsorption of copperions by variable charge soils showed that the release of hydrogenions consisted of a rapid process and a slow process.For variable charge soils, the rapid process was getting less and less distinct when the pH approached about 4 from higher value.At about pH4, the amount of hydrogen ions released after 10 min of addition of copperions accounted for only 30% of that after 65 min of addition of copperions.The release of hydrogen ions by adsorption of constant charge soils was much quicker than that by adsorption of variable charge soils.Even at pH 3.8, the amount of hydrogen ions released after 0.5min of addition of copperions accounted for 56% of that after 65 min of addition of copperions.The exchange ratio H/Cu during the adsorption of copperions was larger for variable charge soils than that for constant charge soils.When 0.1 mol L^-1 NaNO₃ was used as indifferent electrolyte in suspension of constant charge soils, the ratio H/Cu increased.

Abstract:This paper deals with activation kinetics of accmulat ive phosphorus in fluvoaquic soils and red soils, as is influenced by organic matter.Four kinetic equations can well describe the activation of accumulative phosphorus.Removing organic matter with H₂O₂ accelerated act ivat ion of the accumulative phosphorus in fluvoaquic soils, but had no significant influence on red soils.Incubation with addition of 2% glucose promoted activation of the accumulative phosphorus in red soils, but did little in fluvoaquic soils.

Abstract:Two clay samples from B horizon in Alfisols developed from granite and distributed in subtropical zones, covering 30~32 north latitude were treated with DCB solution and 1/3 mol L^-1 Na-citrate solution after DCB solut ion treatment respectively The X-ray diffractometry patterns of the clay samples before and after the treatments show that: there were hydroxy materials in interlayer spaces between expansible silicate layers of the soil clay tested They could be extracted by DCB Na-ci-trate solution and mainly derived from vermiculite or some of them also could be derived from smectite.The differential FTIR spectra of the DCB Na-citrate solution treated samples show the presence of hydroxy-aluminosilicate(HAS), hydroxy-Al interlayers.These results provide evidence that HAS occurs in the interlayer spaces of expansible minerals in Afisol in central China.

Abstract:Five kinds of low-molecular-weight organic acids were chosen for investigating the effect of organic acids on Al release from kaolinite.The results showed that organic acids could accelerate the release of Al from kaolinite due to formation of Al-organic acid complexes.Organic acids increased the soluble Al in the order oxalic acid> citric acid> malonic acid> malic acid> lactic acid.The ability of releasing soluble Al of oxalic acid, citric acid and lact ic acid decreased with the increase of pH, and the effect of pH on the release of soluble Al in oxalic acid system was the most remarkable, whereas the soluble Al increased with pH in malic acid system.The enhanced release of soluble Al by organic acids increased with the increase in concentration of the organic acids.The amount of exchangeable Al in the systems of malic acid and lact ic acid at lower pH(pH 3.5 and pH 4.0) was larger while that at higher pH(pH 4.5 and pH 5.0) was smaller than that in the control system.Citric acid decreased the exchangeable Al in the pH range of 3.5 to 5.0, and oxalic acid did in the range of 3.5 to 4.5.In the citric acid system at pH 4.0, exchangeable Al decreased with the increase in the concentration of citric acid.Whereas the exchangeable Al increased with the increase in the concentration of the organic acid at f irst and then decreased gradually in malic acid system at the same pH.Organic acids can also influence the distribut ion of Al released from kaolinite between kaolinite surface and solution.In the malic acid system, most of Al existed as exchangeable Al on kaolinite surface at lower pH, while most of Al existed as soluble Al in solution at higher pH.In oxalic acid system, most of Al existed as soluble Al in solution and the proport ion of exchangeable Al to total Al released was small in the range of studied pH.The different effects of organic acids on Al release were caused by chemical equilibria in these systems, including dissolution equilibrium of kaolinite, adsorption and desorption of Al, adsorption and desorpt ion of organic acids, dissociation equilibria of organic acids and complexation equilibrium between Al and organic acids.

Abstract:Based on the culture experiments, the mechanism of K mobilization from minerals has been studied with flow extraction technique by simulating the types and the concentrat ions of organic acids that plant roots excretes under P def iciency The results showed that organic acids significant ly stimulated K release from minerals, and the release of K increased with the concentration of organic acids Moreover, the mobilizing ability was closely correlated to the type of the organic acids and minerals The release of K from feldspar and muscovite was simulated by a transfer function model The simulated data was correlated with the measured data It indicated that the transfer function model is useful in studying mobilization of structural K in K-bearing minerals.

Abstract:Humification coeff icients of organic materials and annual mineralizat ion of soil organic carbon were determined in f ield experiments.Amounts of organic materials application were estimated by statistical data to analyze input and output of organic carbon pools in typical arable soils in important agricultural areas of Eastern China in order to evaluate preliminarily.their functions as source or sink of atmospheric CO₂.Humification coefficients in arable soils of agricultural areas of Eastern China changed in the order: Songnen plain (crop straw 0.37, crop roots 0.47, green manure 0.26, livestock manure 0.54) > Red soil hilly region (with corresponding values of 0.28, 0.45, 0.25, 0.42) > Xialiaohe plain (values: 0.35, 0.39, 0.22, 0.33) > Huanghuaihai plain (values: 0.25, 0.32, 0.18, 0.27).Humification coefficient did not changed proportionately with temperature and rainfall and was multiply influenced by environmental factors, especially soil properties.Under realist ic application of organic materials, Songnen plain, Xialiaohe plain, Huanghuaihai plain and Red soil hilly region would have a soil organic carbon formation annually of 538.0 kg hm^-2, 679.7 kg hm^-2, 760.7 kg hm^-2 and 1 059.7 kg hm^-2.Annual mineralizat ion amounts of soil organic carbon are 905.3 kg hm^-2, 723.5 kg hm^-2, 723.1 kg hm^-2 and 782.9 kg hm^-2, respectively.The C balance, calculated as the difference between input and output of soil organic carbon, suggested a deficit (decreasing organic C) in the arable soil of Songnen plain, an increasing organic C content in the paddy soil of Red soil hilly region, an equilibrium in arable soils of Xialiaohe and Huanghuaihai plains.These values determine their funct ions as source or sink of atmopheric CO₂.

Abstract:Contour hedgerow system has been promoted for soil conservation and soil fertility improvement through the use of prunings for the system as mulch green manure However, decomposition process of organic C in the prunings is a key factor affecting nutrient release of prunings Organic C decomposition of prunings from six species of hedgerows was studied by the litterbag method The results indicated that most of the decomposable organic C decomposed within the first 2 weeks in the prunings from Desmodium rensonii and Leucaena leucocephala, within 4 weeks from Tephrosia candida and Aldizia yunnanensis, and more than 8 weeks from Acacia dealbata and A cacia mearnsii, Organic C of prunings incorporated into soil decomposed faster than that used as mulch Cumulative percentage of decomposed organic C could be fitted well by exponent models C_t=C₀(1-e^-kt) or C_t=C₀₁(1-e^-k₁t)+₀₂(1-e^-k₂t) (where C_t represents organic C by time t, C₀ and C₀₁ represent the decomposable fractions of organic C, C₀₂ is the resistant fraction of organic C in the prunings, and k, k₁ and k₂ are the rate constants of C₀, C₀₁ and C₀₂, respectively), and the latter model seems to be more reasonable. The results also indicated that initial C/N ratio was negatively correlated with percentage of C decomposed during the first 12 weeks. Itwas recommended that half life of prunings organic C could be used as a criterion for their nutrient availability to crops in short period under contour hedgerow intercropping.

Abstract:Responses of five wheat varieties to increasing soil salinity were determined through pot culture experiment.Subordinate function value method (SFVM) was adopted in this paper to evaluat e salt resistance of five wheat variet ies comprehensively.Relative water content (RWC), relative electrolyte leakage percentage (RELP), leaf expansion rate (LER), dry matter stress index (DMSI), relative survival percentage (RSP), spike format ion percentage stress index (SFPSI) and grain yield stress index (GYSI) were introduced as the indexes of evaluation.The results of comprehensive evaluation by means of the subordinate degree comprehensive value of growth and physiological characters and stress indexes of yield characters and their average value showed that "Zhishen No.2" and "Lumai No.19" were of the highest subordinate degree comprehensive value (∑X(u)) and the largest average value (X(u)) of these indexes among five wheat varieties under extreme soil salinity, whereas "Lumai No.23" was of the smallest.It meant that "Zhishen No.2" and "Lumai No.19" were of stronger ability of salt resistance, whereas "Lumai No.23" was of less ability relatively.The statistics also showed that there was positive correlation between the stress indexes of yield characters and subordinate degree of growth and physiological characters.

Abstract:With the aid of Object-oriented design and a new programming language——Java, a physicallybased model of hydrological-saline processes in soil was built on the basis of salt and water balanced model and mechanism model.This model is a daily-time step, multiple-layer model of soil water-salt balance.As a case study of the model, hydrological dynamics of soil in Changling, Jilin province was simulated with results verif ied to be consistent with the observed soil moisture data in 1997.The dynamics of salt, alkaline and pH was simulated on two types of soil in 1997, with Aneurolepidium chinense and Suaeda corniculata growing on it respectively.Comparing with the experimental data, the simulation results can express the dynamics of saline and alkaline in different seasons.

Abstract:With a one year indoor silt loam column simulation experiment, regularity of evaporation of groundwater under different groundwater conditions was studied, and so was the relationship between soil electric conductivity (of 0~40cm layer) and total amount of evaporation.The results showed that even under different groundwater conditions total amount of evaporation was in linear relationship with duration of the experiment, that the lower the mineralization of the groundwater was, the more sensitively related the cumulat ive amount of evaporation was to variation of the mineralization of the groundwater, and that the deeper the groundwater table was, the more sensitively related the cumulative amount of evaporation was to variation of the depth of groundwater table.The relationship of total amount of evaporat ion with groundwater table as well as groundwater salinity was thus set up.After mineralized groundwater influenced 0~40cm layer soil, soil electric conductivity there was logarithmic to total amount of evaporation when the groundwater table was at 85cm or 105cm, but exponential when the groundwater table was at 155cm.

Abstract:A pot experiment was conducted to study soil nitrogen(N) supply capacity in eroded and improved red soils.The eroded red soils were derived from Quaternary red clay and red sandstone.The improved red soils derived from Quaternary red clay had been applied with organic manure or inorganic fertilizers for more than 10 years.Results showed that the amount of soil N mineralized and supplied to plant in the soil derived from red sandstone was higher than in that derived from Quaternary red clay.Soil N supply capacity of the improved red soils increased significantly with the soil applied with organic manure taking the lead.When N fert ilizer was applied to eroded soils the N taken up by plant was low, with high N residue left in the Quaternary red clay in particular, and unaccounted-for N was low with a lower value in Quaternary red clay.When N fertilizer was applied to improved soils efficiency of N fertilizer was high.Both plant and soil recoveries in the improved soil applied with organic manure were higher than in that applied with inorganic fertilizers.

Abstract:By analyzing the correlations between plant physiological indexes (such as net photosynthetic rate(Pn), transpiration rate (E), stomatal conductance (Gs) and, intercellular CO₂ concentration (Cint)), and environmental factors (such as photon flux density, atmospheric CO₂ concentration, atmospheric temperature, air humidity etc.), and by computing absolute value of differential of the correlation equation, it is found that the correlation between physiologic indexes and environmental factors varies with nitrogen rate, which in turn affects the sensitivity of the physiologic indexes to the environmental factors.

Abstract:The emphasis of this study is laid on effect of alfalfa growth on soil water eco environment based on data obtained from actual measurements in a long term experiment.At first, yield of fresh alfalfa and its change with the growth life, and the relationship between grass yield and precipitation were analysed.Then, the signif icance of measuring soil water at depth for calculating consumption and revealing effects of alfalfa on water eco environment were presented.Difference in calculating soil depth resultsed in different conclusions in analysis of effects on water eco environment.It pointed out that in the Loess Plateau the annual consumption is more than the annual precipitation for alfalfa which has deep roots more than 10 meters.Therefore cont inual growth of alfalfa can lead to desiccation and form a desiccative layer below the upper soil layer, which affects the way of water cycle on land.It is concluded that in order to slow down or prevent formation of the drying layer an appropriate productivity goal of grassland should be set and relevant agricultural technological measures are proposed.

Abstract:The study shows that Hg and Cd had a remarkable inhibitory effect on soil urease activity, with Hg+Cd and Hg being the most in extent and intensity, respectively.Urease activity can be an index of Hg or Hg+Cd pollution of soil.The soils were polluted severely when the contents of Hg and Cd in the soil reached 1.613~2.647mg kg^-1 and 481.09mg kg^-1 respectively.In the case of Hg+Cd, the inhibition effect was mainly determined by either of the two elements.Hg and Cd showed weak antagonism in multiple treatments.T emperature and urea concentrat ion could enhance heavy metals' inhibition effect on urease activity.

Abstract:Effect of applied straw on soil total organic C, extractable organic C and structural stability were examined in an incubation experiment.The results showed that with increase in straw application rate, total organic carbon (TOC), sodium pyrophosphate extractable carbon (SPPC), hydrolyzable carbohydrates (HDC) and hot water extractable carbohydrates (HWC) in soils were significantly increased after 6 month's incubation.Water stable aggregates were significantly increased with increase in straw application rate for all 4 soils studied; clay dispersion rates were significantly decreased in 3 soils except 1 saline soil.Though there were not marked differences between the effects of corn stalk and wheat straw on TOC, SPPC, water stable aggregates and clay dispersion, it seemed that HDC and HWC in soils in wheat straw treatment were higher than those in corn stalk treatment.TOC, SPPC, HDC and HWC were all significantly positively correlated with water stable aggregate and negatively with clay dispersion rates, respectively.In all, however, HWC was more correlated to water stable aggregates and HDC was more correlated to clay dispersion rates than others.

Abstract:The relationship between sediment concentration in water current and output of capacitance sensor, and effects of temperature, flow velocity, soil types and its salinity content on the response of capacitance sensor have been studied for the first time by adopting two capacitance sensors different in structure.The results showed that the sediment concentration in water current is in linear correlation with the output of capacitance sensor, and the output of capacitance sensor increases with the temperature, but the effects of flow velocity, soil types and its salinity content on output of capacitance sensor were rather less.

Abstract:Impact of irrigat ion with arsenic-containing sewage from chemical fertilizer factory on soil arsenic content was evaluated based on sampling of representative soils along Huafei River and in the suburbs of Kaifeng city.The results showed that soil arsenic content varied among different irrigation patterns with higher soil arsenic content in high rate sewage irrigation area than in sewage irrigation and mixed irrigation areas.Soil arsenic content steadily increased along Huafei River from drainage out let downstream and showed a clear regularity as a function of the distance perpendicular to the direction of main stream and soil utilization patterns.The safe sewage irrigation duration obtained by correlation analysis was 30~35 years.Irrigation with clear water was an effective way to lower soil arsenic content.

Abstract:自可持续发展的概念提出以来,科学家们一直在研究衡量可持续发展状态的指标和方法以支持可持续发展的决策。生态足迹的研究方法是1992年William Rees和他的学生Wackernagel提出并于1996年完善的。生态足迹是指按可持续发展方式,支持给定数量的人口消费所需要的生物生产型土地面积^[1]。由于是采用看得见的足迹来反映人类消费对自然的影响,生态足迹研究方法自提出以来,已经得到了广泛地应用^[2]。本文旨在用当前国际上流行的生态足迹理论,来定量衡量中国的可持续发展状况。

Abstract:微生物与植物共生关系是生命科学中当前一个活跃的研究领域,特别是固氮共生体系。人们在这方面已经有了相当深入的认识,尤其在固氮共生结构的组织学及其形成机理方面^[1]。载于《土壤学报》2001年第38卷第3期379～382的“茄子及西红柿诱发根瘤内生菌的观察研究”一文存在模糊的概念,对研究材料没有具体确切的描述,数据可疑,结论牵强附会。现提出下面几点质疑与学术界同行讨论。