• Volume 42,Issue 5,2005 Table of Contents
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    • DESIGNING OF SOIL CLASSIFICATION EXPERT SYSTEM BASED ON GEOGRAPHICAL INFORMATION SYSTEM

      2005, 42(5):705-711. DOI: 10.11766/trxb200409130501

      Abstract (2391) HTML (0) PDF 602.22 K (2921) Comment (0) Favorites

      Abstract:The Soil Taxonomy offers a theoretic basis for establishment of a soil classification expert system(SCES),which divides soil types according to quantitative soil indexes.The Geographical Information System(GIS) technology offers an effective tool for automatic mapping of soil classification.This paper concentrates on reasonable methods of developing SCES and automatic soil mapping by simulating thinking processes of soil classification experts and using the GIS technology.Firstly,objectoriented methods are used to express the experience and knowledge of soil diagnostic horizons and diagnostic characteristics of soil classification experts;and on such a basis,decision tree structures and consequence ways are discussed.Then a logic structure of the SCES,methods to combine geographic information with automatic soil classification,and the framework of an automatic soil classification searching system based on GIS and ES are brought forth from the angle of knowledge expression of soil classification experts and construction of an inference engine.

    • THE EXPERIMENT OF OPTIMUM METHODS OF RENEWING GIS’S DATA BY GPS SOLID SURVEY IN THE SOIL EROSION FIXED QUANTITY MONITORING

      2005, 42(5):712-719. DOI: 10.11766/trxb200409070502

      Abstract (2012) HTML (0) PDF 1.01 M (1976) Comment (0) Favorites

      Abstract:This paper introduces how to use GPS on-the-spot survey to update outmoded GIS data in quantitative monitoring of soil erosion.This method involves field survey instruments composed of GPS software and receiving equipment,outline for field survey,conversion of projection of measured data,and updating of outmoded GIS data.In comparison with the RTK technology commonly used in the mapping circle to update land use maps,it is more economical,quicker and more practical,and moreover,its position finding and updated GIS' s data are more reliable after systematic errors are eliminated.The result in the experimental area indicated that the precision of monitoring soil erosion quantificationally was increased 7 percent,comparing the updated land use maps by GPS to the old maps.For increasing the precision of monitoring soil erosion and water quality from nonpoint source pollution,it is attached to update the changed boundary of the land use maps on hill or massif by GPS on-thespot.

    • GENETIC CHARACTERISTICS AND TAXONOMY OF SOILS IN THE JINGGANG MOUNTAINS]

      2005, 42(5):720-729. DOI: 10.11766/trxb200410100503

      Abstract (2079) HTML (0) PDF 815.27 K (2628) Comment (0) Favorites

      Abstract:To popularize application of the Chinese Soil Taxonomy and elucidate positions of the soils of the Jinggang Mountain in the system,this paper attempted to classify the soils on the Jinggang Mountains,which are located on the boundary between Hunan and Jiangxi.Comprehensive analysis of findings of out-door investigations and results of indoor tests of soil samples for physical and chemical properties showed that the main properties of the soils in the Jinggang Mountains varied regularly with the altitude.According to the Chinese Soil Taxonomy (3rd edition),the altitudinal zonation of the soils in the region consists of Udic Ferrosols(<500 m),Udic Argosols(500-1 000 m),Perudic Argosols(1 000-1 500 m),and Orthic Primosols (1 500-1 900 m).

    • INFLUENCE OF ATMOSPHERIC PRECIPITATION ON SOIL LEACHING AND DESALINIZATION IN THE NORTH CHINA PLAIN

      2005, 42(5):730-736. DOI: 10.11766/trxb200407220504

      Abstract (1806) HTML (0) PDF 542.31 K (3053) Comment (0) Favorites

      Abstract:In the North China Plain,the average annual precipitation is 500-600 mm,74% of which is concentrated in the rainy season.triggering soil leaching and desalinization.When the precipitation exceeds 300 mm in July and August,soil desalinization will be observed,and when a rainfall is over 25 mm,the effect of desalinization in root zone soil will be seen.The key to enhancing the effect of rainfall on salt leaching and desalinization lies in setting up drainage and water management systems、Beginning from 1964,main drainage rivers had been excavated and dredged in the Haihe River Plain year by year,and in 1975 all the five rivets systems of the Haihe River got their own drainage outlets to drain flood.exces"ive rainwater and saline groundwater.Along with the water drainage a lot of salt is drained into the sea.The end of the 1960s the beginning of large-scale exploitation and utilization of groundwater for irrigation.The practice of well irrigation lowers the groundwater table,thus functioning as drainage,reducing phreatic evaporation,increasing rainfall ifiltration and consequently enhancing the effect of rainfall on salt leaching and desalinization.And the practice of replenishing the groundwater with river water Freshens the groundwater.As a resalt,soil secondary salinization has been controlled,and large areas of saline-alkali land ameliorated in the North China Plain.

    • WIND TUNNEL EXPERIMENT ON EFFECTS OF DIFFERENT CULTIVATION PATTERNS ON SOIL WIND EROSION IN AGRO-GRAZING ECOTONE, INNER MONGOLIA

      2005, 42(5):737-743. DOI: 10.11766/trxb200409270505

      Abstract (2103) HTML (0) PDF 577.34 K (2942) Comment (0) Favorites

      Abstract:Soil was collected from Taipusi County,Inner Mongolia,for wind tunnel experiment.Results indicate that different cultivation patterns result in objective difference in wind erosion.In the wind tunnel experiment,seven cultivation patterns were simulated with the soil,such as subsoiling,deep plowing,plowing and scrunching,10 cm high wheat stubbles,10 cm high buckwheat stubbles,10 cm high benne stubbles,and no-stubble.Among them,the pattern of plowing and scrunching was the highest in wind erosion rate,being 124.8gm-2 min-l,whereas the pattern of benne stubbles the lowest,being 15.14 g m-2 min-1.The seven farming patterns were in the order of plowing and scrunching>no-stubble>subsoiling>10 cm high stubble of buckwheat>deep plowing>10 cm high stubble of wheat>10 cm high stubble of benne in average wind erosion rate.The relationship between wind erosion rate and wind speed was analysed,showing that in terms of effect of wind erosion control,the patterns of plowing and scrunching and no-stubble were the poorest and the patterns of benne stubbles,wheat stubbles and plowing were the best,and the patterns of subsoiling and buckwheat stubbles were medium.The conclusion drawn in this paper is of some significance for reference in controlling wind erosion in dryland agriculture in the agro-grazing ecotone.

    • CORRESPONDENCE ANALYSIS OF VEGETATION COMMUNITIES AND SOIL ENVIRONMENTAL FACTORS ON ABANDONED CROPLAND ON HILLY-GULLIED LOESS PLATEAU

      2005, 42(5):744-752. DOI: 10.11766/trxb200411110506

      Abstract (2443) HTML (0) PDF 804.06 K (3646) Comment (0) Favorites

      Abstract:Based on observation of 33 plots of abandoned farmland in Ansai,a loess region of hills and gullies,sequence of vegetation communities and their relationships with soil environmental factors in these fields were analyzed through f:orrespondente Analysis and Canonical Correspondence Analysis.The results show that there are mainly 4 vegetation communities during 40 years of succession:Artemisia scoparia dominated community(Ⅰ),Lespedeza davurica and Stipa bungeana dominated tommunity(Ⅱ),Artemisiu gmelinii dominated community(Ⅲ)and Bothriochloa ischaemuu dominated community(Ⅳ).The species compositions of the 4 communities displayed relatively strong continuity and progressiveness.In comparison,the soil nnder Community Ⅰ was higher in soil moisture content in 0-200 cm layers and available phosphorus content,Community Ⅱ in total nitrogen and available nitrogen content,Community Ⅲ in total phosphorus content and soil water content in 200-500 cm layers,and Community Ⅳ in available potassium and organic matter content.Organic matter,total phosphorus,available phosphorus and soil water content in 0-200 cm layers are important factors significantly affecting variation of vegetation on abandoned cropland in the hilly-gullied Loess Plateau.To revegetate the land quickly and control soil erosion effectively,it is essential to take measures such as transplanting or sowing C4 plants and applying fertilizers.

    • SOILS AND TRACE ELEMENTS IN THE DISTRIBUTION AREA OF LONGEVOUS PEOPLE IN RUGAO COUNTY OF JIANGSU PROVINCE

      2005, 42(5):753-760. DOI: 10.11766/trxb200409080507

      Abstract (2786) HTML (0) PDF 1.05 M (2671) Comment (0) Favorites

      Abstract:Health and life-span of a person mainly depend on factors such as inheritance,living habit and environment.Among the three factors,environmental is an important one affecting the phenomenon of longevity.The study on spatial distribution of the density of longevous people of Rugao County,Jiangsu Province,shows that the over-90 rate(number of people over 90 years old per 100 000 in population) is high in some areas.It is higher in areas of well-developed loamy Cambosols and Anthrosols in the northern,eastern and southeastern part of the county than in areas of sandy Cambosols in the western part and areas of clayey and weakly-developed Cambosols in the southern part.According to the correlation and principal component analysis,available Se,Zn and B in soils were significantly correlated with the over-90 rate,and belonged to the same principal component,indicating that available Se,Zn and B or their combination in the soil of Rugao are probably the most important trace elements beneficial to the health and the life-span of the people in Rugao County.

    • RESIDUES OF HCH AND DDT IN TYPICAL AGRICULTURAL SOILS OF HUANG-HUAI-HAI PLAIN, CHINAⅠ. RESIDUES IN SURFACE SOILS AND THEIR ISOMERIC COMPOSITION

      2005, 42(5):761-768. DOI: 10.11766/trxb200410080508

      Abstract (2528) HTML (0) PDF 756.47 K (2894) Comment (0) Favorites

      Abstract:Contents of HCH and DDT were measured and their isomeric compositions were investigated in 129 soil samples of typical agricultural surface soils gathered from 7 counties in the Huang-Huai-Hai Plain,China,to understand the present status of residues of the organochlorine pesticides commonly used in the past and to assess their potential toxicology to the environment.HCHs(HCHs=a-HCH+(3-HCH+y-HCH+8-HCH)was detected in all the samples analyzed,with an average content (±SD) of 4.01(±2.21)μg kg-1,while DDXs(DDXs=4,4'-DDE+4,4'-DDD+2,4'-DDD+4,4'-DDT) was found in 93% of the samples,with an average content(±SD) of 11.16(±17.29)μg kg-1.The former was found far less than 50 μg kg-1 in these samples,while the latter exceeding 50 μg kg-1 in 3.1% of the samples,an upper limit of the norms for HCH and DDT set by the state for quality of the first-class soil.Generally,agricultural soils from the Huang-Huai-Hai Plain were less contaminated with organochlorine pesticides than the samples from Tianjin,Europe,and USA.The highest contents of β-HCH with mea ±SD value of 2.48±1.88 μg kg-1)among 4 HCH isomers and of 4,4'-DDE(with mean ±SD value of 6.91±13.67 μg kg-1)among 4 DDT isomers were observed.Pesticide residues were not proportional to soil organic matter.

    • CARBON CONTENTS IN SOILS AND CROPS AS AFFECTED BY LONG-TERM FERTILIZATION

      2005, 42(5):769-776. DOI: 10.11766/trxb200407120509

      Abstract (2542) HTML (0) PDF 725.55 K (3759) Comment (0) Favorites

      Abstract:A long-term stationary field experiment was carried out to study the effect of application of organic manure,chemical fertilizers or their mixture on soil carbon storage and carbon fixation by plants.The experiment was designed to have 7 treatments;organic manure (OM),half organic manure plus half fertilizer N(1 /20M),fertilizer NPK(NPK),fertilizer NP(NP),fertilizer NK(NK),fertilizer PK (PK) and control(CK).The treatments,supplied with balanced nutrients of N,Y and K,showed a marked increase in the storage of soil organic carbon,while those deficient in nutrient supply a significant decrease.Only in Treatments OM and 1/20M,where additional organic carbon was supplied,a net uxrease in organic carbon in the soil was observed.The relationship between the storage of organic carbon(Y) and the input of organic carbon(X) can be well described by the following linear equation:Y=1.3231 X-1942.7(r=0.9840,n=7).Treatments NPK,NP and 1/20M were the highest in both crop carbon fixation and organic carbon contents in crop straws and stubbles that can be returned to the soil.So,if the fixed carbon in the straws and stubbles return to the soil,Treatments NPK.NP and I/20M would have the biggest storage of organic carbon in the experiment.However,the combined application of chemical fertilizer and organic manure is the optimal for agricultural field based on economic consideration.

    • EFFECTS OF LAND USE ON ORGANIC C CONCENTRATION AND STRUCTURAL PROPERTIES IN ALPINE GRASSLAND SOIL

      2005, 42(5):777-782. DOI: 10.11766/trxb200409270510

      Abstract (2394) HTML (0) PDF 572.70 K (3825) Comment (0) Favorites

      Abstract:Cultivating native pasture to plant oat or some other species of grasses is generally recommended as a way to alleviate grazing pressure on native grassland and to improve winter forage levels in high altitude regions,however,its effects on soil quality have not been well understood.This study selected three types of land use,fencing pasture(FP),fencing pasture plus subsequent 25-year oat(Arrhenatherum elatius) cultivating(FP+SO),and fencing pasture plus subsequent 7-year perennial grasses (Elymus nutarrs and Bromus anermis)cultivating(FP+SPG),to investigate changes in soil organic C concentration and some soil physical properties caused by land use transition.The results show that compared with FP,FP+SO and FP+SPG significantly decreased soil organic C density in 0-30 cm depth by 27.7% and 8.5%,and mean weight diameter(MWD) by 46.9% and 42.6%,respectively.Meanwhile,FP+SO and FP+SPG significantly increased soil bulk density and particle density,and significandy decreased soil porosity.We concluded that decrease in aggregate stability and porosity,and increase in bulk density and particle density,were all related to reduction in soil organic C concentration by cultivation.

    • EFFECTS OF P AND Fe APPLICATION ON GROWTH OF Caragana AND RHIZOSPHERIC ENVIRONMENT IN CALCAREOUS SOILS

      2005, 42(5):783-791. DOI: 10.11766/trxb200407260511

      Abstract (2017) HTML (0) PDF 822.54 K (2288) Comment (0) Favorites

      Abstract:Pot and root-box experiment of randomized block and split block design were conducted for determinating effects of P application and combined application of P and Fe2+ on growth of Caragana and its rhizospheric environment in calcareous soils with sufficient water supply.Results of the pot experiment show that caragaaa biomass increased with P application rate.Under the stress of low P or P deficiency,shoot growth of Caragana was restricted,the ratio of root/shoot increased and soil pH decreased rapidly.The root-box experiment demonstrates that effect of combined application of P and Fe2+ on Caragana biomass varied with the ratio.When the P and Fee+application rate was P205 0.15 g kg-1 and FeSO4·7 H20 0.03 g kg-1,respectively,an evident increase in Caragana biomass was observed over other treatments.The effect of combined application of P and Fe2+ on available P in the rhizosphere (0-6 mm) decreased rapidly with increasing distance,and was just in reverse on soil pH.Resups show that soil pH in the rhizosphere was mainly controlled by P application rate,and the application rate of Fe did not have much effect on soil pH in the rhizosphere or the root zone.

    • FORMS OF PHOSPHORUS LEACHING IN LOESSIAL SOIL

      2005, 42(5):792-798. DOI: 10.11766/trxb200409060512

      Abstract (2154) HTML (0) PDF 584.42 K (2331) Comment (0) Favorites

      Abstract:Based on the soil phosphorus gradient obtained from two long-term stationary fertilizer experiments on loessial soil,an intact soil cores (20 cm in depth) experiment was conducted to study forms of phosphorus in leachate.The results show that phosphorus leached from loessial soil mainly in dissolved form(TDP),which accounted fur 82.5 percent of the total P(TP) in the leachate,and particulate phosphorus(PP) for only 17.9%.Molybdate reactive phosphoms(MRP),being a chief cnmponent of the dissolved phosphorus,constituted on average 77.1% of the total P in the leachate,whilst dissolved organic phosphorus (DOP) did 13.8%.The maximum TP concentration of the leachate reached to 3.95 mg L-1 and TDP 3.57 mg L-1,during the 60-day experiment with a sum irrigation rate of 357 mm in total,approximately equal to 36% of the total annual precipitation and irrigation.The maximum phosphorus loss by leaching was observed reaching to 1082 g hm-2.The results also indicated that MRP,TDP and TP concentrations of the leachate were significantly correlated with Olsen-P content of the plough layers.

    • ECOLOGICAL FUNCTION OF “PADDY FIELD RING” TO URBAN AND RURAL ENVIRONMENT Ⅰ. CHARACTERISTICS OF SOIL P LOSSES FROM PADDY FIELDS TO WATERBODIES WITH RUNOFF

      2005, 42(5):799-804. DOI: 10.11766/trxb200501030513

      Abstract (2190) HTML (0) PDF 593.29 K (2774) Comment (0) Favorites

      Abstract:Results of field trials revealed that P losses from soil with runoff are closely related to land use patterns,which are in the order of:mulberry garden>>vegetable fields≥paddy in wheat season>paddy in rice season.The annual mean total P loss from paddy field under wheat-rice crop rotation was about P 0.84 kg hm-2,which was equivalent to 2.5% of the total P applied.P loss from vegetable field reached P 0.6 kg hm-2 in 5 months due to a very high content of soil available P,and from mulberry garden P 1.1 kg hm-2 in 4 months.In terms of forms of P moved with runoff,about 70%-80% was found to be Particle P(PP),while the rest (20%-30%)was dissolvable P(DP).Of the dissolvable,inorganic P(D1P) accounted for only 30%-40% while organic P(DOP) for about 60%-70%.Mechanisms of runoffs were closely related to land use patterns and determined strength,frequency and amount of runoffs.Flooded paddy field is surrounded by ridges,and embedded with a plowpan below the cultivation horizon developed after long term rice cultivation.Thus flooded paddy field is recognized as a closed system for runoff.But runoff would occur occasionally in case of heavy raiushowers that lead to overflow of the overlying water,and the runoff flow from flooded paddy field is defind as "occasional runoff".In thr case of vegetable field or paddy under winter wheat,the field is open to free runoff as long as there is rain because it is not protected by ridges.This type of runoff is called "open runoff".As mulberry gardens in this area are usually located on upland with varying degrees of slope in the rural area or along both sides of canals or rivers,runoff in this case is accelerated by the gravity and could carry more particles with faster velocity from the upper to the bottom along the slope,which is defind as "intensified runoff".The break point of P runoff losses from the two types of paddy fields tested was P 25-30 mg kg-1 (Olsen-P).The present average soil available P in paddy soils in this region was around P 12-15 mg kg-1,which is still far below the break point under the current management practice in this region.As long as the regular fertilization regime is maintained,paddy fields will not pose a source of non-point source P pollution within the next 5-10 year.Therefore,setting up a "Paddy field Ring" around villager and/or town,vegetable bases/or mulberry gardens should be an ecological and valuable means for controlling the non point source P pollution with runoff.

    • EFFECT OF DOM ON PHOSPHATE SORPTION IN LAKE SEDIMENTS

      2005, 42(5):805-811. DOI: 10.11766/trxb200407160514

      Abstract (2232) HTML (0) PDF 623.88 K (2457) Comment (0) Favorites

      Abstract:Effects of DOMs extracted from lake sediments different in trophic level from the Wuli Lake and the East Taihu Lake on phosphate sorption isotherms and sorption kinetics were studied through sorption experiment.The results indicate that:(1)DOM did not show much effect on phosphate sorption kinetics in lake sediments.Phosphate sorption proceeded at a high rate during the first 10 hrs,and basically reached equilibrium after 20 hrs.But the phosphate sorption rate was increased by DOM,especially during the initial period of 0-0.5 h,from 82.34 to 97.18 mg kg-1 h-1 in the sediment from the East Taihu Lake,and from 12.21 to 59.17 mg kg-1 h-1 n the sediment from the Wuli Lake;(2) DOM obviously changed the phosphate sorption isothernis of the sediments,suggesting it enhanced the sorption process and improved the efficiency of phosphate sorption on the lake sediments,from 123.3 to 164.8 L kg-1 on the sedimem from the East Taihu Lake and from 94.56 to 206.3 L kg-1 on the sediment from the Wuli Lake;(3) The effect of DOM on phosphate sorption was greater on the sediment from the Wuli Lake that was high in pollution and in organic matter content than that on the sediment from the East Taihu Lake that was moderate in nutrient level and low in organic matter content.

    • EFFECT OF INTERACTION BETWEEN SOIL MOISTURE AND PHOSPHORUS ON RICE CULTIVATION IN AEROBIC SOIL CONDITION

      2005, 42(5):812-818. DOI: 10.11766/trxb200406220515

      Abstract (1961) HTML (0) PDF 615.37 K (2664) Comment (0) Favorites

      Abstract:Both field and pot experiments were carried out to study effects of interaction between soil moisture content and P application rates on biomass and yield of rice cultivated in aerobic soil.The results show that the effects of soil moisture content and P application rate were significant on biomass and yield of rice growing in aerobic soil,and the interactive effect of the two factors was very evident,showing a sequence of grain>shoot>root.Although the biomass and)field of rice had been hardly-affected by soil moisture content,when it was 80% or 100% of saturated water content(SWC),but markedly by soil moisture content 60% of SWC.Biomass and yield of rice increased with the increasing in P application rate:in the aerobic soil,showing that the soil moisture content 80% of SWC was enough to maintain rice growth in the aerobic soil.In order to gain higher yield of rice,it is essential to pay attention to P application or take some measures to improve soil P utilization efficiency.

    • CHANGES IN MICROBIAL ACTIVITIES AND ITS COMMUNITY STRUCTURE OF RED EARTHS POLLUTED WITH MIXED HEAVY METALS

      2005, 42(5):819-828. DOI: 10.11766/trxb200409290516

      Abstract (2220) HTML (0) PDF 1.06 M (3145) Comment (0) Favorites

      Abstract:An incubation experiment designed by second-order regression orthogonal rotation was conducted to study soil microbial activities and functional diversity of microbial community in red earths polluted by copper,zinc,lead and cadmium compound state.The results showed that soil microbial activities and functional diversity of microbial community were inhibited very significantly or significantly by heavy metals compound pollution.Moreover,soil microbial biomass carbon(SMBC),soil basal respiration and functional diversity of microbial community are very sensitive to the level of heavy metals pollution.At the same lime,the relative biological toxicity of heavy metals to soil microbial parameters were in the order:cadmium>copper>zinc>lead.The results of canonical correlation analysis showed that the first(r=0.885 8)and second(r=0.932 8) canonical correlation coefficients were significant,which suggested that there exists a stable feed-back mechanism between soil mieroor-ganism and heavy metals contents in red earths.The main factors analysis opened out that the total microbial ecological index might be a useful parameter to assess changes in soil quality with management of these highly contaminated soils,So it is feasible to use soil total microbial parameters as primary biochemical index to evaluate the effect of heavy metals compound pollution tin red earth environmental quality.

    • EFFECTS OF DEHP ON DEHYDROGENASE ACTIVITY AND MICROBIAL FUNCTIONAL DIVERSITY IN SOIL

      2005, 42(5):829-834. DOI: 10.11766/trxb200411180517

      Abstract (2319) HTML (0) PDF 503.52 K (2811) Comment (0) Favorites

      Abstract:A pot culture experiment was carried out to study effects of 100 mg kg-1 DEHP on dehydrogenase activity and microbial diversity in Fimi-Orthic Anthrosols,as well as effects of mung bean planting on DEHP toxicity.DEHP-treaunent significantly depressed dehydrogenase activity,which decreased by about 30% after 30 days,and then increased slightly after 60 days,but was still lower than that in the control(p<0.05).The BIOLOG results show that Shannon index,Simpson index,McIntosh index and evenness of soil microbial communities were all significantly lower in the DEHP-treated soil than in the control,which indicated that DEHP pollution decreased functional diversity of the soil microbial communities.Mung bean planting enhanced dehydrogenase activity and soil microbial activity,alleviated bnt did not completely eliminate the toxicity of DEHP.

    • DISTRIBUTION, TRANSPORTATION AND BIOAVAILABILITY OF SELENIUM IN YUTANGBA, HUBEI PRONVINCE, CHINA

      2005, 42(5):835-843. DOI: 10.11766/trxb200407220518

      Abstract (2316) HTML (0) PDF 860.64 K (2388) Comment (0) Favorites

      Abstract:Yutangba is one of the most typical high-Se areas in Enshi Prefecture in China.Comprehensive studies were conducted in order to better understand distribution and variation of selenium in soils.plants and water bodies of Yutangba.The results show that high-Se plants and soils are mainly distributed in the northwestern part,Shangba and Xiaba of Yutangba,where exposure of Se-rich carbonaceous strata is found.No significantly positive relationship between soil Se and plant Se was found,which indicates Se uptake by plants is not always controlled by concentration of total Se in the soil.In the past 30 years,selenium content in the soil has remained almost unchanged whereas plant Se has showed a significant declining trend,indicating that in the soil Se available to plants has obviously decreased.Although water samples high in Se can be collected from streams flowing through the Se-rich carbonaceous strata or abandoned stone coal spoils,no obvious variation of Se content in water was observed,demonstrating that the release of Se has reached a geochemical equilibrium.The distribution of Se in Yutangba,apart from topographic and geological factors with regard to Se-rich rocks,is also related to pathways of Se transportation.The exposed Se-rich carbonaceous strata in the northwestern part of Yutangba is a necessary condition for developing high-Se areas,but the high-Se soil in Shangba and Xiaba of Yutangba is attributed to human activities such as cultivation and mining.Local farmers often use Se-rich "stone coals" as fertilizer or soil amendment,thus leading to Se further accumulation in food chain,of which the impact is long term.Therefore should the local government not take adequate measures or make reasonable planning for the exploitation of the Se resources in Enshi Prefecture,the risk of Se poisoning is still very high in Yutangba and some other high-Se places in Enshi Prefecture.

    • >Reviews and Comments
    • PREDICTIVE SOIL MAPPING BASED ON A GIS, EXPERT KNOWLEDGE, AND FUZZY LOGIC FRAMEWORK AND ITS APPLICATION PROSPECTS IN CHINA

      2005, 42(5):844-851. DOI: 10.11766/trxb200412300519

      Abstract (3235) HTML (0) PDF 943.20 K (3056) Comment (0) Favorites

      Abstract:Detailed soil spatial and attribute information are now basic parameters for environmental modeling and land management applications.The accuracy and efficiency of conventional soil surveys,based on the polygon model and the manual mapping practice,are quite low.A geographical information system(GIS) and expert knowledge based-fuzzy soil inference scheme(soil-land inference model,SoLIM) was developed to overcome the problems faced by the conventional soil survey.The scheme consists of three major components:(i) a model employing a similarity representation of soils,(ii) a set of inference techniques for deriving similarity representation,and (iii) application of the similarity representation.According to case studies conducted in Wisconsin,U.S.A,SoLIM improves the accuracy and efficiency of soil survey.Soil type and properties maps based on SoLIM are better than these based on conventional techniques in term of both spatial detail and attribute accuracy.The accuracy of the soil series maps based on SoLIM is about 80%.Moreover,soil mapping by means of SoLIM is about ten times faster than by conventional ones and saves about 2/3 in cost.However,how the SoLIM works highly depends on the availability and quality of environmental data and the quality of soil,environmental relationship model for the study area.The Second Soil Survey in China was conducted 20 years ago.Recent intensive land use activities may have greatly impacted the soil conditions.It's quite necessary to update the soil data in China for agricultural purposes.The SoL.IM framework can provide great assistance in updating soil resource inventory.At the same time,the availability of spatial data,spatial information proceasing technology and human resources related to GPS,GIS and RS also make it possible to apply the SoL.IM approach in the Chinese soil survey.However,the degree of success of the SoL.IM highly depends on the quality of knowledge on soil environmental relationships in the study area.The knowledge about soil-environmental relationships used for the SoLIM in USA comes mainly from local soil survey experts.Although experts in soil taxonomy can provide much help for soil survey in China,the number of experts who focus on soil mapping in local areas is small,which will pose a major problem in using the SoL.IM approach in China due to its reliance on human expertise for soil-environmental relationships.If we try to discern the soil-environmental relationships by field sampling,we will need a large amount of samples,which is too expensive and too slow.Thus,we must develop new approaches for extraction of knowledge on soil-environmental relationships.These new approaches could include new sampling methods,such as purposive sampling to reduce fieldwork and data mining for extracting knowledge from existing soil maps.

    • >Research Notes
    • DECOUPLING INDICATORS OF SOIL EROSION FOR AGRO-ENVIRONMENTAL ASSESSMENT

      2005, 42(5):852-856. DOI: 10.11766/trxb200402260520

      Abstract (1821) HTML (0) PDF 609.95 K (2890) Comment (0) Favorites

      Abstract:在全球变化和人为活动日益增强的背景下,现代土壤侵蚀不仅使表土遭受流失,引起土壤质量下降,导致非点源污染,同时也与洪旱灾害,粮食安全,甚至社会稳定密切相关。近年来,土壤侵蚀问题引起国际社会的广泛关注,土壤侵蚀被列为农业生态环境健康,土壤质量,水质和空气质量(风蚀)诊断的首要指标。各国政府都提出相应的政策措施控制土壤侵蚀的发生。近年来我国政府采取了一系列生态环境建设的政策措施,这些措施一方面在经济和科技投人的前提下使得生态环境得到了初步改善,而另一方面这些环境保护政策给地方农业,工业和商业等社会经济的发展带来巨大的压力。如何确切地评价土壤侵蚀、水土保持措施和政策法规,怎样制定对社会经济发展压力最小且环境效益最高的水土保持政策是政府以及自然科学家和社会科学家关注的焦点。本文简要地介绍了国际新近发展的退藕理论;提出农业生态环境持续发展的土壤侵蚀评价的退祸指标体系,以供同仁探讨。

    • EFFECT OF CULTIVATION ON ORGANIC CARBON COMPOSITION IN A HISTOSOL IN THE SANJIANG PLAIN, CHINA

      2005, 42(5):857-859. DOI: 10.11766/trxb200408300521

      Abstract (2156) HTML (0) PDF 259.13 K (2744) Comment (0) Favorites

      Abstract:土壤有机碳是土壤质量评价和土地资源可持续利用管理中必须考虑的重要指标,其质量和数量影响土壤的物理、化学和生物特征及其过程。但是,利用总有机碳来评价土地利用方式对土壤碳动态的影响,特别是在土壤中稳定有机碳背景较高的情况下,是非常困难的[1]。因此,需要敏感性评价指标研究土壤有机碳动态。用物理方法把土壤有机质分为游离态轻组、包裹态轻组和重组等不同组分,对于准确评价土地利用变化影响土壤碳过程具有重要意义[2,3]

    • PROPAGATION PROPERTIES OF ELECTROMAGNETIC WAVE IN SATURATED NONCOHESIVE SOIL AND LABORATORY TEST

      2005, 42(5):860-865. DOI: 10.11766/trxb200405250522

      Abstract (2068) HTML (0) PDF 522.13 K (2329) Comment (0) Favorites

      Abstract:目前工程中大多采用取样法测试土的孔隙比, 该方法对土层产生扰动,深层取样困难,不能长期定点监测且测试有时间滞后性。与之相比,现场测试方法能克服这些缺点,具有取样法无法比拟的优势。电磁法是近年来发展很快的一种快速的现场测试方法。该方法利用电磁波在土中的传播速度和土介质介电常数与土的物理性质指标关系测土的孔隙比和含水量研究电磁波在土中的传播特性,进而获得电磁波在土中的传播速度和土介质介电常数与土的孔隙比和含水量之间的关系,作为现场测试土的孔隙比和含水量的依据,具有重要的意义。

    • EFFECTS OF ORGANIC ACIDS ON SURFACE CHARGE CHARACTERISTICS OF PERMANENT CHARGE SOILS

      2005, 42(5):866-870. DOI: 10.11766/trxb200408160523

      Abstract (1556) HTML (0) PDF 370.18 K (2219) Comment (0) Favorites

      Abstract:低分子量有机酸在土壤中随着各种有机物的分解和生物的生命活动不断形成、转化并累积,形成一些较高浓度的有机酸微区,影响养分的生物有效性和根际系统中的物质循环。随着根际化学的兴起, 根际土壤化学和元素行为越来越引起广大土壤科学工作者的关注[1-6]

    • ADSORPTION AND DESORPTION PROCESSES OF SDBS AND THEIR MECHANISM BY USING TWO-STEP ADSORPTION MODEL

      2005, 42(5):871-874. DOI: 10.11766/trxb200406210524

      Abstract (1995) HTML (0) PDF 356.98 K (2346) Comment (0) Favorites

      Abstract:表面活性剂是一种重要的精细化工品,素有“工业味精”之称,具有起泡、洗涤、增溶等作用,广泛应用于工业、农业、环保等领域。据统计,全球表面活性剂的使用量自1992年以来一直以3%的年增长率增长,预测到2050年可增长到1.2×108ta-1,而且主要增长份额在亚洲,尤其在中国[1]。十二烷基苯 磺酸钠(Sodium Dodecyl Benzene Sulfonate,简称SDBS),是生产量最大的表面活性剂之一。

    • EFFECTS OF NITROGEN SUPPLY ON FLAG LEAF SENESCENCE AND GRAIN WEIGHT IN WHEAT GROWN UNDER DROUGHT OR WATERLOGGING FROM ANTHESIS TO MATURITY

      2005, 42(5):875-879. DOI: 10.11766/trxb200407120525

      Abstract (2048) HTML (0) PDF 428.38 K (2340) Comment (0) Favorites

      Abstract:小麦生育后期的显著特征是叶片衰老与籽粒生长发育同步进行。花后土壤干旱和渍水状况下,小麦发生早衰,植株光合功能不可逆转地迅速下降,物质运转分配等生理过程发生紊乱,导致生长发育和衰老进程及生理代谢功能失调,最终影响其产量和品质[1,2]。研究表明,小麦灌浆期土壤干旱或渍水 导致旗叶细胞内活性氧的生成与清除平衡遭到破坏,引起自由基的积累和膜脂过氧化,使膜系统的结构和功能受到损伤,从而造成植物细胞的伤害,降低了清除自由基能力,加速旗叶衰老[3,4],最终导致粒重下降[5]

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