Abstract:Paleosols formed during the geological past are archives of paleoenvironment. Although pre-Neogene paleosols were formed a long long time ago，buried deep and subjected to strong diagenetic alteration，their pedogenetic characteristics are the basis for studying and reconstructing paleoenvironment. In an attempt to reconstruct paleoenvironment of the study regions，where calcareous paleosols of Cretaceous were discovered at several localities，a research project was launched to study pedogenesis of the paleosols. Results show that A-and B-horizons of the soils altered morphologically，but the difference between the two remained distinct；organic matter contents were generally higher in the surface soil layer than in the subsurface layer，and a calcic horizon （Bk） was commonly spotted abundant in carbonate nodules. Slickensided peds and precipitation of the calcites along the plant roots were observed in thin sections of the paleosols. The paleosols were sorted as loamy sand and sandy loam with texture being a bit too coarse. The Bk horizons of the soils were relatively enriched with Ca，Mn and Sr，but quite low in other macro-and micro-elements，like Ba，Sc，Nb，Th，U，Cr，V，Co and Ni. And negative anomaly of δCe and δEu as well as enrichment of heavy rare earth elements were detected in Bk horizons relative to A hozrions in paleosols. Classification of the paleosols in line with the Chinese Soil Taxonomy and US Soil Taxonomy were tried. Based on the findings，it is concluded that climates between semi-humid and semi-arid once appeared in Zitong-Bazhong area （Sichuan Basin） during the Berriasian-Valanginian age，in Jinlingsi-Yangshan Basin （Liaoning Province） during the Barremian age，and in Songliao Basin （Heiliongjang Province） at the Maastrichtian age.

Abstract:Conventional soil maps are the major data source for information on soil spatial distribution which is essential in watershed management and eco-hydrological modeling. Due to the limitations of conventional soil mapping techniques，the level of spatial detail and attribute accuracy in conventional soil maps are not high. With the development of geographic information technology and the accumulation of high quality detailed spatial data on environment，the question about how to update the conventional soil maps using these new techniques and high quality data comes up. Based on the assumption that soil polygons in the conventional soil maps do contain basic relationships between soil types and environment，we have developed a new method to extract knowledge on soil-environment relations embedded in conventional soil maps and then update the soil maps with the knowledge using the detail environmental data. The method consists of the following four steps，1） Fuzzy c-means clustering of environmental data to obtain the combinations of environmental factors；2） Relating the combinations of environmental factors to soil types based on conventional soil maps；3） Extraction of knowledge on the soil-environment relationships；4） Prediction of soil spatial distribution using the SoLIM （Soil-Land Inference Model）. This method was applied in Wakefield，New Brunswick，Canada for updating its 1∶20 000 conventional soil map. It was showed that the updated soil map had more spatial details than the original one. And verification at independent validation points in the field indicated that the digital soil map depicting spatial distribution of soil associations with drainage classes was about 20% higher in accuracy than the conventional soil map. It is therefore concluded that the proposed method is an effective way to update conventional soil maps.

Abstract:Spatial distribution of the soil types in the Manas River Basin was analyzed quantitatively by means of the Geographic Information System and the principles of Landscape Ecology. Results show that the dissociation index of the soil types in the basin varies in the range of 0～3，which means they are quite concentrated in distribution. A spatial fractal structure does exist with the soil. And the mosaic complexity of the soil types differs remarkably. The highest fractal dimension belongs to the meadow saline soil，being 1.709，that is to say，the most complex in mosaic complexity. The highest average shape index lies with the new soil，being 3.684，which means this type has a higher aspect ratio，as well as a higher deviation degree from a square or round. The diversity index of the soil types is 3.037 and the uniformity index is 0.803，indicating their high heterogeneity and high diversity within the research area. The dominance index of the soil types is 2.465 and the patch density index is 0.0273，which show that the soil in Manas River Basin is dominated by a few soil types，such as the semi-fixed aeolian soil.

Abstract:Choosing a more reasonable vegetation index is critical to higher precision of appraisal of soil and water conservation. In this study，an experiment of twelve plots (5m×20m) was set up on the red soil hills in Changting of Fujian Province，South China. These plots were under two types of vegetation cover (pure forest and forest-grass) separately and had six levels of vegetation coverage (80%，60%，45%，30%，15% and 5%). Parameters of leaf area index (LAI)，vegetation fractional coverage (VFC)，rainfall，runoff and sediment were measured during the period of 2007 and 2008. Using the statistical analysis method，characteristics of soil erosion under different vegetation covers various in coverage in the region were studied，and soil erosion quantification by LAI and VFC was analyzed for stability and reliability. Results indicate that compared to the control plot，pure Pinus massoniana forest did decrease soil erosion modulus to a certain extent，but runoff insignificantly. In contrast，the mixture of forest-grass cut runoff by 25% and soil erosion modulus by up to 90%，suggesting that the vegetation fraction of forest-grass is more effective in soil and water conservation. The use of LAI to characterize soil erosion modulus under the two types of vegetation cover is able to reach the level of significance (P<0.05)，while the use of VFC is but only under the forest-grass cover. Therefore，it is advisable to choose LAI to characterize soil erosion modulus to evaluate soil and water conservation for more stable and reliable results.

Abstract:Based on the images of post atmospheric correction reflectance (PAC)，top of atmosphere reflectance (TOA)，satellite radiance (SR) and digital number （DN） of a SPOT5 HRG remote sensing image of Nanjing，China，two vegetation indices (VI)，i.e.，normalized difference vegetation index (NDVI)，and ratio vegetation index (RVI) were derived，and compared with the leaf area index (LAI) data acquired from field measurement. A total of 157 LAI-VI relationship models were established. The results show that LAI was positively correlated with VI (r=0.303~0.927，p<0.01). Independent variables of the optimal models corresponding to various vegetations included 2 vegetation indices at 3 radiometric correction levels，indicating potentials of vegetation indices based on different radiometric correction levels in LAI remote sensing retrieval. These optimal models included broad-leaf forest： LAI=-3.345+5.378RVI_SR+7.329NDVI_SR（R²=0.818，RMSE=0.527）；conifer-broad-leaf forest：LAI=1.696+17.076NDVI_DN+137.684（NDVI_DN）²-288.240（NDVI_DN）³（R²=0.919，RMSE=0.440）；shrub：LAI=-0.065+19.112NDVI_SR-113.820（NDVI_SR）²+184.207（NDVI_SR）³（R²=0.900， RMSE=0.448）；grass： LAI=-5.905+6.446RVI_SR+9.477NDVI_SR（R²=0.944， RMSE=0.378）；and total vegetation：LAI=-1.615+7.199NDVI_DN+2.640NDVI_SR+2.105RVI _PAC （R²=0.801， RMSE=0.668）. The study demonstrates that LAI remote sensing estimation of various types of vegetation based on images of different radiometric correction levels contributes to tapping of valuable information from remote sensing images，thus improving accuracy of LAI estimation.

Abstract:Quantitative evaluation of soil fertility quality of the soil under the windbreak forests alongside the Tarim Desert Highway was carried out with the IFI method (soil fertility integrated index). Results show that since the establishment of the windbreak forests,the physical structure,e.g. permeability,aeration property and water-holding capacity,of the soils bioactivity has been improving in various soil layers,and so has the soil biological activity,which is manifested mainly in higher soil microbial biomass C,N and P and enhanced activity of six enzymes,thus leading to stimulation of transformation of soil nutrients and hence differentiation of most nutrient elements between soil layers. Shelter forest soils,older in age,are higher in soil salt content,and display a phenomenon of salt accumulation in the surface soil. IFI values differ slightly between soil layers of the same soil profile,but is closely related to forest tree growth indices. In a word,the soil fertility quality of the shelter forests,drip-irrigated with salty water alongside the Tarim Desert Highway is on the way of continuous improvement.

Abstract:The study on characteristics of water conduction in gravelly soil is beneficial to modelling water movement in this porous type of medium. Saturated hydraulic conductivities and soil water characteristic curves of two soil samples，loam and clay loam，separately and three types of mixtures of fine earth and rock fragments，2～10 mm in particle size and different in lithologic characteristics，were measured in lab with the indoor constant water head method and centrifuging method. Unsaturated hydraulic conductivities of the mixtures were calculated using the van Genuchten. Mualem model，and effect of gravels on soil water transmitting ability was analyzed. Results show that introduction of gravels low in weathering degree into the clay loam significantly increased saturated hydraulic conductivity of the soil，and the higher the introduction rate，the more significant the effect. However，the introduction of gravels high in weathering degree did not improve much its soil structure，and rather decreased its saturated hydraulic conductivity. The unsaturated hydraulic conductivity of the medium of gravels low in weathering degree increased first with rising soil water suction and got over that of the soil-rock fragment mixtures and soils，and then dropped promptly down below that of the two groups of media. When soil water suction was near zero，the unsaturated hydraulic conductivity of soil-rock fragment mixtures high in gravel content was higher，whereas when soil water suction was great，the unsaturated hydraulic conductivity of the mixtures decreased with increasing gravel content in the soil. The findings may serve as reference to the study on water balance in gravelly soil.

Abstract:Soil pore systems under no tillage (NT) and moldboard tillage (MT) in the black soil zone of Northeast China were extracted from soil thin sections with digital image process techniques and the multifractal characteristics of soil pore structure were studied with method of moment. Results indicate that NT decreased the macroporosity (>500 m) in〖LM〗 the surface layer (0~5 cm)，but increased the total porosity and macroporosity at 10~15 and 20~25 cm depth. Multifractal characteristics were observed at 64~1 024 pixel scales and generalized dimensions (D_q)，multifractal spectral (f (α)) and other related parameters reflected characteristics of the pore structure in the soil sections under NT and MT. The multifractal spectra of the pores in the surface layer apparently leaned toward the right side but approached to symmetry with increasing depth. Compared to MT，NT increased the Δα（α_-10-α₁₀） and ΔD (D_-10-D₁₀) of soil pore structure，and complexity of soil pore system，especially at 10~15 cm and 20~25 cm in depth.

Abstract:Effects of pore-water velocity and pH on Cu，Pb，Zn and Cd transport in quartz sands were studied，through a stable flow miscible displacement experiment，and breakthrough curves(BTCs) of the tracer bromide(Br^-) and Cu/Pb/Zn/Cd were obtained. And their adsorption coefficients were determined through indoors batch equilibrium experiments and then their retardation factors(R_d) were worked out. Based on the results of the experiments with the aid of Software CXTFIT2.1 (A nonlinear least-squares optimization approach) BTC of Br^- was fitted with the equilibrium CDE model，yielding dispersion coefficient (D). On such a basis，BTCs of Cu，Pb，Zn and Cd in conditions of different pore-velocity and pH were fitted with the non-equilibrium CDE model，and dynamics of their concentrations at various depths and in parallel experiment were predicted. Results show that the transport of Cu/Pb/Zn/Cd in quartz sand columns increased with pore-water velocity，but decreased with rising pH. Conclusively，the non-equilibrium-theory-based two-site model describes better transport of Cu，Pb，Zn and Cd in such a scenario as of this experiment.

Abstract:A total of 420 farmland soil samples were collected, 96 from Suzhou area and 324 from Jiaxing area, for analysis of composition of PAHs and concentrations of the 15 types of PAHs under priority control with the aid of HPLC and for exploration of sources of the PAHs in the soil, using the ratioing technology and PCA. Results show that the total content of PAHs varied in the range from 45.4 μg kg^-1 to 3 703 μg kg^-1 and from 9.00 μg kg^-1 to 2 421 μg kg^-1 in Suzhou and Jiaxing, respectively. The mean concentration of B\[a\]P in the soils of Suzhou reached 21.4 μg kg^-1, far beyond the maximum allowable value of 20.0 μg kg^-1 set by the Former USSR. The content of PAHs in Suzhou displayed an increasing trend from south (Wujiang County) to north (Xiangcheng County), and much higher than in Jiaxing. And the content of PAHs in soils of Wujiang County and Jiashan County of Shanghai was rather higher. Phe, FluA, BbF, IP, and Pyr were the dominant PAHs in Suzhou, while Phe, FluA, Pyr, Chry, and BbF were in Jiaxing. The sources of the PAHs in the soils of the two regions were quite similar, mainly biomass, coal combustion and petroleum.

Abstract:A pot experiment in greenhouse was carried out to investigate effects of application of rhamnolipid (RH), a type of biosurfactant on the effect of PAHs-specific degrading bacteria (DB) in bioremediation of soils that have long been contaminated by PAHs. Results indicate that application of RH in addition to DB inoculation significantly increased total PAHs and promoted degradation of PAHs different in number of rings in the soil. After 90 days of incubation, the PAHs degradation ratio of Treatments RH, DB and RH+DB reached 21.3%, 32.6% and 36.0%, respectively, and increased by 333.0%, 563.3% and 633.0% as compared against that (4.9%) of the control. In addition, the average PAHs degradation ratio declined with the number of rings of the 15 PAHs. It was also found that the number of PAHs degrading bacteria, dehydrogenase activity and polyphenol oxidase activity in soils of Treatments DB and RH+DB were much higher than in Treatment RH and in CK, but differed slightly between Treatment RH and CK, suggesting that the mechanism of DB promoting degradation of PAHs in the soil is different from that of RH.

Abstract:A batch leaching experiment was conducted to compare the use of EDTA-Na₂ with the use of oxalic acid (OX) in effect of removing heavy metal pollutants from brownfield soils. Also, a two-step eluting method with EDTA-Na₂ and OX was tested in an attempt to find out optimal combination of OX and EDTA. It was found that EDTA-Na₂ was quite effective in removing zinc (Zn), lead (Pb), copper (Cu) and nickel (Ni) from the contaminated soil, but not chromium (Cr). In the experiment, the effect of EDTA did not increase with its concentration, however, OX was effective in removing Cr and the effect increased with the concentration OX used, but its effect of removing Zn, Cu and Ni decreased with its rising concentration. Moreover its effect was particularly low on Pb. The two-step eluting technique using OX (0.20 mol L^-1 for 2 h) and EDTA-Na₂ (0.01 mol L^-1 for 2 h) sequentially could remove the heavy metal pollutants simultaneously and was better than the use of EDTA-Na₂ or OX individually in removing Zn, Cu, Cr and Ni. Its total removal rate of Zn was 75.21%, of Pb 21.30%, of Cu 59.81%, of Cr 60.72% and of Ni 62.10%. It is more noteworthy that the two-step eluting technique was very effective in removing metals of non-residual form, with removing rate reaching 91.93% for Zn, 57.75% for Pb, 75.33% for Cu, 73.94% for Cr, and 77.99% for Ni. The findings of the study indicate that the sequential elution technique using different combinations of chemical eluents different in capability of removing heavy metals is a high-efficiency method to remedy heavy metal pollutant contaminated brownfield soils.

Abstract:Iron oxide-kaolinite association is an important component of the soils in South China and a critical factor influencing physical and chemical properties of these soils. Hence, formation and transformation processes of crystalline iron oxide-kaolinite association and their influencing factors were studied with Fe (II) as catalyst. Results show that Fe(II) accelerated association of crystalline iron oxide with kaolinite, which offset the inhibiting action of kaolinite to some extent on the formation of crystalline iron oxides When the molar ratio ( R ) of Fe (II) to Fe (III) was in the range of 0.04～0.06, Fe(II) accelerated association of kaolinite with lepidocrocite, goethite and hematite, and when R ≥0.1, magnetite-kaolinite association readily formed. In addition, Fe(II) accelerated association of kaolinite with lepidocrocite and goethite at pH 5～6 and 50～60℃, with hematite at 80℃ and neutral pH, and with magnetite at pH 9. Kaolinite reduced the catalytic effect of Fe(II) on formation of crystalline iron oxides and influenced type and morphology of the iron oxides formed. These findings may serve as valuable reference for the study on formation and transformation of iron oxides and iron oxides-kaolinite associations in natural environments.

Abstract:Effects of removing organic matter with hydrogen peroxide, adding 1% humic acid, and removing free Fe-Al oxides with DCB (dithionite-citrate-bicarbonate) on adsorption of oxalic, citric, tartaric and malic acids by red soil developed from red clay were studied with the batch equilibrium method. Results show that due to the possible change of solution pH, surface sites, soil structure, activity of surface group, and the formation of oxalate, removal of organic matter slightly increased adsorption amount of low molecular weight organic acids, but the increase was not obvious; due to the possible change of surface charge, the cover of surface sites, the activity of Fe oxides, and the protonation of groups, addition of humic acid slightly decreased the adsorption amount after one month incubation, but the reduction was also not obvious; and the adsorption amount was reduced significantly in the soil with 3.79% of the free Fe-Al oxides removed because of the significant decrease of positive charge, and the reduction of adsorption amount varied with the kind of organic acids, showing an order in reverse to that of the original soil in terms of maximum adsorption of organic acids.

Abstract:Samples of montmorillonite and clay fractions (＜2 μm) of black soil, yellow-brown soil, red soil, and latosol were used in the test to determine mean free binding energies (ΔG_bi) between monovalent cations Na⁺, and K⁺ and various clay particles with the ion activity method and the suspension Wien effect method. Results show that the values ofΔG_bi determined of Na⁺ to black soil, yellow-brown soil and montmorillonite with the two different methods were quite similar, and the relative errors ofΔG_bi determined with the ion activity method in relation to those determined with the Wien effect method varied in the range from 24% to 10%; the values ofΔG_bi determined of K⁺ to black soil, and yellow-brown soil with the two different methods were almost the same, with relative errors lingering below 2%. But the relative errors ofΔG_bi determination of red soil were about 11.5%. The results also indicated that the sodium glass electrode is applicable to this experiment only when the difference in pH between the standard solution and the suspension to be tested is less than 0.5; and the liquid-membrane potassium electrode can be used to determine K⁺ activity in the soil suspensions in this experiment, but can not in the suspensions of montmorillonite. However, it is still impossible to directly apply the Wien effect method to determination of binding energy of monovalent cations to the variable-charge soils, positive in charge, such as latosol.

Abstract:Based on the long-term fertilization experiment in the arid upland fields on the Loess Plateau that started in 1984, soil respiration, soil temperature and soil moisture in the 0—10cm soil layer of winter wheat fields different in fertilization during the summer fallow season (from July to September) were monitored with the dynamic closed chamber method (LI-8100 USA), and dynamics of soil respiration and its relationships with environmental factors were investigated. Results show that soil respiration varied drastically within the range from 5.05μmol m^-2 s^-1 to 0.06 μmol m^-2 s^-1 with a variation coefficient of 116.5% and a mean of 2.00μmol m^-2 s^-1. For the whole study period, in terms of soil respiration, the treatments followed a decreasing order of NPM > M > NP > N and CK, with cumulative CO₂- C emission being 2.0, 1.6, 1.2, 0.8 and 0.8 Mg ha^-1, respectively. The relationship between soil respiration and soil moisture appeared in an extremely significant parabolic curve (p<0.01), which explains 55% of the variation of the soil respiration. Although soil respiration was in extremely significant linear relationship with soil temperature (p<0.01)，soil temperature could explain only 19% to 39% of the variation of soil respiration. Strength of the response of soil respiration to ploughing significantly (p<0.05) was positively related to soil microbial biomass carbon and soil organic carbon showing a linear relationship, but not to total nitrogen or soil dissolved organic carbon (p> 0.05); the effects of rainfall on soil respiration depended on soil moisture before a rainfall event. In soils deficient in soil moisture for long, rainfall significantly stimulated soil respiration, while in soils sufficient in soil moisture, rainfall inhibited soil respiration. Magnitude of the effect is closely related to soil organic carbon, total N, soil soluble carbon and soil microbial biomass carbon. Soil respiration during the fallow season may be affected by soil moisture, alteration of wet and dry, soil temperature, rainfall, ploughing, and soil organic carbon level.

Abstract:A pot experiment was conducted, using the soil from a pot that had been planted with winter wheat, to investigate availability of residual fertilizer nitrogen (N) from the winter wheat season applied in combination with inorganic and organic fertilizer (IOF) to the rice(O.sativa L.cv. Wuyujing 7) following the winter wheat. Results show 1) the residual N effect was significant on growth of the rice. Treatment IOF was 49.3% and 14.9% higher than Treatment IF (inorganic N fertilizer) in grain yield in clay loam and clay, respectively; 2) compared with Treatment IF, Treatment IOF maintained a higher mineral N content in the soils. Treatment IOF significantly increased the ratio of organic-fertilizer-sourced ¹⁵N /inorganic-fertilizer-sourced ¹⁵N in mineral N at the heading stage in clay loam and at tillering, jointing and heading stages in clay, and it also increased significantly the percentage of organic-fertilizer-sourced ¹⁵N in microbial biomass N (MBN) at the tillering and jointing stages, and that of inorganic-fertilizer-sourced ¹⁵N at the tillering, jointing and heading stages; 3) compared with Treatment IF, Treatment IOF increased the relative distribution of inorganic-fertilizer-sourced ¹⁵N in the reproductive organ (by 60% in the clay loam and by 52.6% in the clay), while decreased that in the vegetative organs (by more than 30% both in the clay loam and clay); compared with Treatment OF (organic fertilizer N), Treatment IOF decreased the relative distribution of organic-fertilizer-sourced ¹⁵N in the reproductive organ (by 20% in the clay loam and by 22.7% in the clay), while increased that in the roots (by 90% in the clay loam and by 240% in the clay); and 4) in comparison with both Treatment IF and OF, Treatment IOF increased residues of inorganic-fertilizer ¹⁵N in the soils, and also the recovery rate of organic fertilizer ¹⁵N in both plant and soils. As a result, the fertilizer ¹⁵N loss rate (NLR) decreased correspondingly during the rice season (by 17% and 16% for inorganic fertilizer ¹⁵N, and by 15% and 56% for organic-fertilizer ¹⁵N in the clay loam and clay, respectively). In a word, Treatment IOF reduced fertilizer N loss from the winter wheat-rice rotation system by increasing N recovery rate in the soil-plant system.

Abstract:Sediments play an important role in nitrogen (N) and phosphorus (P) cycling and eutrophication in lakes. Spatial and temporal variations of ammonium nitrogen (NH₄⁺-N) in sediments were monitored for one year (May 2003-May 2004) at 5 sampling sites (Haigeng, Dounan, Luojiacun, Xinjie and Kunyang) typical of Lake Dianchi with the aid of the GPS technology, for analysis of characteristics of dynamic variations of NH₄⁺-N in sediments of different depth, different times and different regions of the lake. Results show that the NH₄⁺-N contents in the sediments averaged 74.57mg kg^-1 and varied in the range of 45.55~170.1 mg kg^-1within a year. It varied sharply with seasons, showing a general trend of being high in summer and low in winter, but the trend differed slightly from site to site NH₄⁺-N contents in sediments also varied significantly with depths, showing a trend of surface (0~5cm) > middle (5~10cm) > bottom (10~20cm) in summer and of middle > surface >bottom in winter. In three layers of sediments it varied in the range of 18.71~172.9 mg kg^-1, 29.55~192.2 mg kg^-1 and 19.93~123.8 mg kg^-1, separately. In terms of mean NH₄⁺-N content, Luojiacun was the highest and Dounan was the lowest. NH₄⁺-N in the sediments showed an extremely significant positive correlation with NH₄⁺-N in and pH of the waterbody, but a significant negative correlation with available-P in the sediments, which indicates sediment NH₄⁺-N is the source and sink of NH₄⁺-N in the waterbody and influence release of phosphorus from the sediments.

Abstract:Influences of temperature and duration of incubation were investigated through laboratory incubation experiment on transformation of monocalcium phosphate monohydrate (MCP), monoammonium phosphate (MAP) and diammonium phosphate (DAP) in black soil. Results show that high temperature increased fixation of the selected fertilizers in black soil and favored formation of Al-P; an increase of temperature from 5°C to 25°C and 50 days of incubation resulted in reduction of We-P in Treatments MAP and MCP by 51% and 42%, respectively, and simultaneously in increase in Al-P by 110% and 45%, respectively; at the initial stage of the incubation, not much influence of temperature on formation of Ca₈-P and Fe-P was observed, but it was getting obvious with the incubation going on. At 25°C, the formations of Ca₂-P and Ca₈-P were not much affected by duration of the incubation; at the beginning of the incubation, Al-P was formed rapidly, but the formation rate declined with the incubation going on; the formation of Fe-P displayed a reverse trend; the formation of Al-P was in significant negative linear correlation with that of We-P. Compared with MAP and MCP, DAP was more suitable for application in black soil.

Abstract:Cotton production plays an extremely important role in the local economy, and the income from cotton cultivation is one of the major financial sources for farmers in Xinjiang. The cotton production of Xinjiang that is the biggest cotton production base in China has been developing rapidly since the 1990s, and now the sowing area, yield per hectare and total yield of cotton all rank first among the provinces in China. To better understand effect of long-term monoculture of cotton on temporal and spatial variation of 5 soil microelement (Total Mo, Total Cu, Total Zn, Total Mn, Total Fe) contents in the field, cotton fields different in cultivation history (1, 5, 15, 20 and 30 years) were selected in South Xinjiang for the study on relationship between soil microelement contents and history of continuous cropping. Results show that with the cropping going on, in the plow layer (0~20cm) total Mo decreased, showing a unitary negative linear relationship, while total Cu, total Zn and total Mn first rose up, peaking in year 7~10, 10~12 and 17~18, separately and then declined, dropping back in year 14~17, 20~22 and 32~34 separately to the initial value, showing a quadratic functional relationship. In the sublayer (30~50cm), the microelements decreased significantly, showing a unitary negative linear relationship with the time and demonstrating a tendency of long-term monoculture leading to deficiency of microelements in the layer. And in the botton layer (50~60 cm), the totals of these microelements increased to a various degree, but did not show any apparent functional relationship with the time. With the monoculture going on, the lower the microelement in content in the soil layer (0~60cm), the more apparent the fall of its content, with Mo in particular, which was followed by Zn, Cu, Mn and Fe. Therefore, in fields that have long been cultivated with cotton continuously, it is essential to supplement microelement fertilizers, like Mo, Zn and Cu, and in addition perform deep tillage so as to raise microelement contents in the sublayer.

Abstract:Variation of soil zinc in form in calcareous soil, a potentially zinc-deficient soil, was analyzed after application of zinc fertilizer in the soil with a view to investigating availability and aftereffect of Zn fertilizer. Results show that wheat did not improve much its yield, but did Zn concentration in grains; and the effect varied from genotype to genotype. In the soil Zn appeared mainly in the following forms; mineral Zn accounting for 91.5%-97.6% of total Zn, organic-matter-loosely-bonded Zn for 1.34%-5.53% and carbonate-bonded Zn for 0.47%-1.55%. Application of Zn fertilizer increased various fractions of Zn in the soil, such as exchangeable Zn, organic-matter-loosely-bonded Zn, and carbonate-bonded Zn and the manganese oxides bounded Zn, and most of the applied zinc transformed into mineral form. Wheat plantation helped Zn in the soil turn into available form. Application of nitrogen fertilizer enhanced Zn uptake by wheat, and expanded the fraction of mineral Zn. Principal component analysis reveals that the fractions of exchangeable Zn, organic-matter-loosely-bonded Zn, and carbonate-bonded Zn are to some extent indicators of Zn availability.In calcareous soil carbonate-bounded Zn and organic-matter-loosely-bonded Zn account make up a considerable portion of total Zn.Therefore, to enlarge the pools of the two fractions of Zn is key to management of soil Zn nutrient in calcareous soil.

Abstract:To investigate effects of warming on soil nutrients, microbes and soil enzyme activities in alpine meadow and alpine swamp meadow in the hinterland of the Qinghai-ibet Plateau of China, an experiment was carried out from August 2006 to September 2008 using open-top chambers and capped chambers for comparison.Results show that (1) in alpine swamp meadow, warming increased the average air temperature by 2.4 ℃, and the soil temperature within the depth of 5 cm by 0.8℃ in the open-op chambers and by 4.9℃ and by 14.℃, respectively, in the closed chambers; while in alpine meadow, it increased soil temperature by 0.1℃ and by 3.3℃ in the open-op chambers and closed chambers, respectively.(2) soil nutrients in the two meadows responded differently to warming.In the alpine swamp meadow, soil organic carbon and total nitrogen decreased in the soil layer 0~5 cm in depth, but increased in the soil layer 5~20 cm in depth in both chambers, while in the alpine meadow, they increased in the soil layer 0.cm in depth, but decreased in the soil layer 5~20 cm in depth.(3) warming significantly increased carbon and nitrogen contents in soil microbial biomass, but the greater magnitude of the temperature rise in the closed chambers suppressed metabolism of soil microbes, thus leading to decrease in carbon and nitrogen contents in microbial biomass.(4) The activities of catalase, urease and proteinase increased to a various extent in two meadow soils, but the activity of alkaline phosphatase decreased, and saccharase responded differently between the two meadow soils.The increase in activities of catalase, urease and proteinase and the decrease in saccharase and alkaline phosphatase in the closed chambers were less in magnitude than in the open-op chamber, which is similar to the variation trend of the population of soil microbes.The different responses of soil organic carbon and total N to warming is attributed to difference between the two meadows in soil properties, hydrothermal regime, soil metabolism, vegetation, soil fauna (animal and microbe), population and micro-iodiversity.

Abstract:A strain of bacterium a45, an antagonist to capsicum wilt ( Ralstonia solanacearum ), was isolated from the rhizosphere of capsicum. The strain was identified as B. subtilis according to its physiological and biochemical characteristics and 16S rDNA gene sequence. 20%（V/W）of a45 culture was inoculated into a mixture of pig manure compost and amino acid fertilizer, which fermented for 4 days into bio-organic fertilizer (BOF) containing about 2.0×10⁹g^-1 soil of a45. A pot experiment was carried out in greenhouse using soil inoculated with pathogen Ralstonia solanacearum(9.6×10⁶g^-1 soil), and amended with either BOF (5‰ W/W，1.0×10⁷ a45 g^-1 soil) or a45 liquid culture (LC,1.0×10⁷ a45 g^-1 soil) to evaluate effect of the bio-control agents in controlling the wilt disease. Results show that the application of LC and BOF mitigated capsicum wilt incidence by 69.58% and 76.09%, respectively, and promoted growth of the plants somewhat. The population of Ralstonia solanacearum in the capsicum rhizosphere 30 days after application with LC and BOF was decreased by 20.5% and 25%, respectively compared with that in the control. And the population of a45 decreased gradually over time after inoculation in both soils. However, BOF significantly deferred the decrease as compared with LC. Besides, genes ituA、ituB、ituC、ituD，Qk，bam and SboA responsible for synthesis of antibiotics iturin, subtilisin QK, bacillomycin andsubtilosin A, respectively, were detected in strain a45 with PCR, showing that the strain can be used as a biocontrol agent.

Abstract:As one of the major components in soil ecosystem, soil enzyme plays important roles in converting soil nutrient, improving soil fertility and remediating pollutant in soil. This study focused on long term monitoring enzyme activities of three hydrolytic enzyme (urease, invertase, alkaline phosphatase) from fixed sites at fertile land to establish a more realistic index of total soil enzyme activity. The result showed that there is a good correlation between soil enzyme activity and soil fertility. Correlations between soil enzyme activities and characteristics of the soil are significantly or very significantly positive. This suggests that enzyme activities of urease, invertase and alkaline phosphatase in soil environment could be used as an indicator for soil fertility. A new total soil enzyme activity index from this study ( E_t=∑Xi/X) was proposed which is a dimensionless parameter and could be used to compare with each soil samples easily. The E_t can be calculated from monitoring enzyme activity in soil and soil fertility, as the result of total soil enzyme is similar to those of principal component analysis (PCA) and clustering analysis.

Abstract:A study was carried out on variation of fresh weight of a whole leaf and contents of water, soluble sugar, polysaccharide and aloin in leaves of aloes after four years of irrigation with mixtures of seawater and fresh water different in mixing ratio. Results show that no distinct difference was observed between irrigations with 0%, 10% and 25% of seawater in leaf fresh weight, between irrigations with 0%, 10%, 25%, 50% and 75% of seawater in leaf dry weight, and between irrigations with 0%, 10%, 25% and 50% of seawater in water content in the ground part of aloe, and that irrigations with 50%, 75% and 100% of seawater reduced leaf fresh weight by 11.5%, 28.1% and 45.6%, respectively as compared with control (0% seawater), irrigation with 100% of seawater did leaf dry weight by 14%, and irrigations with 75% and 100% of seawater water contents in the ground part significantly.Among the leaves different in position, water content in leaves dropped with intensifying seawater stress, and the effect was more significant in leaves of the lower part than in leaves of the middle and upper parts.Soluble sugar content in leaves of aloe irrigated with seawater increased with the rising seawater ratio. Polysaccharide content in leaves did not vary much with the irrigation Aloin content increased significantly with the rising seawater ratio of the irrigation and peaked in aloe irrigated with 75% of seawaterTherefore, it is concluded that the experiment is successful and that irrigating Aloe vera with mixture of seawater and fresh water of a proper ratio (75%) can save fresh water sources and markedly improve the content of aloin, which is the major element of medicinal effect in aloe.

Abstract:Root exudates of oilseed rape were collected from the plants in water culture, and determined to contain 16 kinds of amino acids with high performance liquid chromatography (HPLC). Chemotaxis of Bacillus subtilis Tu-100 toward the 16 amino acids, oilseed rape roots and sclerotia, were determined separately with the beaker method and petri dish method. Results show that Tu-100 displayed obvioous chemotaxis toward histidine, proline, arginine, aspartic acid and glutamic acid only, and histidine in particular, and toward oilseed rape roots and sclerotia as well; more obvious toward the former than the latter.

Abstract:The development status of domestic and international agriculture was introduced, and the agricultural modernization construction demands under new situation of China was analyzed. According to “high-yield, high quality, efficient, ecological and safety requirements to develop modern agriculture”, concept and connotation were proposed concerning “construction of high value eco-agriculture industrial system of China”. Moreover, principles of high value eco-agricultural model and relevant technology system were constructed. In the end, target system and development direction of “high value eco-agriculture” was analyzed.

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