Abstract:The spatial change of textural layers is one of the important features of alluvial soils. It affects soil water transport and solute movement in field intensely. But the quantitative studies on it are limited. Based on the results obtained in our research,this paper presented two stochastic models- MC (Markov chain) model and MC-LN (Markov chain Lognormal distribution) model for simulating textural profiles of regional alluvial soils using Markov chain theory, and simulated soil textural profiles by Monte Carlo method. Results showed that the vertical changes of textural layers along soil profiles in the research region could be reflected by this two models.But in the probability distribution of textural layer thickness, MC model often brought on more error, and MC-LN model was in accord with the measured data.Considering the far more intensive effects of number and sequence of textural layers in profiles than the error of textural layer thickness on field water and solute movement. two models would be accepted simultaneously.

Abstract:Quaternary red clay and yellow-brown earth coexist in Xuanzhou, Anhui Province.The former is mainly distributed on eroded hills and slopes; the latter mainly on plain,low hills, valleys and feet of hills. According to the investigations of topographical features and typical soil profiles in this region, it was found that the yellow-brown earth horizon was above the Quaternary red clay horizon. With ESR dating method,the yellow-brown earth was dated to 80 ka B. P., while the Quaternary red clay was 240 ka. B. P Comparative study of basic physical and chemical properties and susceptibility of the two soil-forming parent materials showed that the Quaternary red clay suffered stronger weathering than the yellow-brown earth. It indicated a hot and humid climate in the middle Pleistocence, when the Quaternary red clay was formed,and then the climate turned cold in the late Pleistocence. This change resulted in the halt of red earth development and the formation of yellow-brown earth. The red weathering mantle exposed in this region was considered to be formed under the palaeo-climate in the middle Pleistocence; while the yellow-brown earth was mainly affected by the modern climate.

Abstract:The mineralogy of three soils, derived from red sandstone, purple sandstone and red-purple sandstone was studied by XRD, IR, TEM and XRF. Results showed that total chemical composition of these three soils varied greatly, especially for Fe, Ti, Mn and basic elements, which demonstrated that these three parent rocks were formed in different sedimentary environments. It was found that soil derived from red sandstone was mainly composed of disorder kaolinite and halloysite, and some illite and vermiculite, derived from purple sandstone mainly illite, and some halloysite and montmolinite. Meanwhile montmolinite and hematite were the major minerals in soil from red-purple sandstone. The iron oxide minerals of these soils were also varied greatly, no-Al substituted hematite was the only crystalline Fe oxide in soil from purple sandstone and redpurple sandstone; whereas the coexistent goethite and hematite is nearly amount in soil from red sandstone, and Al-substituted amounts of these iron oxides were 16.6 and 2.1 mole % respectively. Difference in types and amount of iron oxides resulted in different colors of these soils.

Abstract:A model for CaCO₃ eluviation and deposition processes in arid area soils called CAEDP, was developed based on mechanisms of chemical thermodynamic process and CaCO₃ deposition process in soil profile, and using other experiences in modeling for reference. The model was validated in the north west Shanxi Province, a typical semiarid area. The results showed that the model simulated the processes of CaCO₃ eluviation and deposition and the pH value in arid area soils realistically, using only a few readily avaible inputs, such as mean monthly temperature, crop growth season,soil water flux, and so on. The model can be used for quantitatively evaluating the effects of factors including climate, biota, topography,parent material, time and human activity on CaCO₃ deposition in soil profile, a relatively slow process in soil development. And the model can also be used for quantitative studies on soil change and global change.

Abstract:Based on the analysis of species composition, amount and distribution of seeds,and species similarity. and its diversity, the properties of soil seed banks on 10 different land utilization systems in Hainan Province were studied. The 10 land utilization systems are Casuarina equisetifolia forest (12 years),Eucalyptus exserta forest (12 years),rubber plantation (40 years),tea tree plantation (28 years),sugarcane plantation, old-field (2 years abandoned dry field),shrub (8 years abandoned shifting cultivation),shifting cultivation (2 years),secondary forest and primeval tropical rain forest.Resuts showed that: A. The amount of seeds of xylophyta species decreased and that of herbaceous species increased with the increase in strength of land-use, while as the amount of seeds increased, the bio-diversity decreased.B. More than 50% species distributed randomly in these soil seed banks of 10 land utilization systems. C. Slash-and-burn cultivation caused not only soil and water loss, but also the degradation of quality and quantity of soil seed banks.

Abstract:Relationship between the molecular connectivity indices and adsorption coefficient (Koc) of nonpolar organic compounds was investigated based on molecular topology.Close linear relationship belween ¹x and logKoc of nonpolar compounds was revealed by the regressive analysis of ¹x and logKoc of 300 organic compounds. Calculation accuracy would be further improved as ¹x^v,²x and ²x^v were introduced into the model. Ffty five percent of the estimated error was within 0.2 log unit for 99 nonpolar compounds studied. A quantitative model was developed for estimating Koc of nonpolar organic pollutant based on molecular connectivity indices.

Abstract:In this paper, effects of freeze-thawing and dry-wetting processes on the formation of soil macropores and preferential flow under simulative conditions in laboratry, and preferential migration of linear alkylbenzene sulfonate (LAS) in soils growing rice and soybean in field lysimeter were studied. Results showed that both freeze-thawing and dry-wetting processes could cause macropores and preferential flow in soils and that the former was stronger than the latter.The duration of preferential penetration of LAS through 1.5m soil monolith was 23 days for both soils growing rice and soybean. However, their leachate volumes of preferential penetration were much different, i. e., 69 mm for soil growing rice and only 9 mm for soil growing soybean. Preferential migration process was not governed by soil adsorption/desorption processes. The leachate volumes in equilibium governed by adsorption/desorption processes in soil were very similar for rice (185mm) and soybean (178mm).The duration of preferential penetration of LAS was 21 and 35 days ahead of equilibium penetration for soils growing rice and soybean, respectively. The peak concentrations of preferential penetration of LAS amounted to 20%-30% of peak concentration of equilibrium penetration in soil growing soybean. This ratio was as high as 30%-86% in soil growing rice. This phenomenon of preferential migration could not be obsearved in repacked soil monolith without macropores.

Abstract:The annual rings of six Masson pine trees and the soils near the tree roots were sampled from the red soil area in Jiangxi Province for the determination of Al, P, Fe,Co, Cu, Zn, and Ba contents. Results showed that the relationship between C(z,t) and C' (z, t) followed the logarithmic linear correlation model:
lgC'(Z)=a(Z)+b(Z)lgC(Z)
where z is atomic number of element, a and b are coefficients, which are related to chemical elements, tree species, climatic factor and soil types. Based on this model the dynamic changes of chemical element contents in soils could be reflected by those in the growth rings of tree.

Abstract:In this work, the effect of cation adsorption and pH on the electrokinetic properties of constant charge soils and variable charge soils were studied. A laterite was used as a representative variable charge soil and yellow brown earth, brown earth,dark brown earth and black soil were used as representative constant charge soils.results showed that the zeta potential of laterite in different electrolyte solutions changed to negative in sign from positive in sign with the increase in pH and an isoelectric point (IEP) occurred on all the zeta potential-pH curves.When the pH value was higher than 5, the zeta potential of laterial in different electrolytes was of the order MnCl₂>ZnCl₂≥CaCl₂>NaCl.On the other hand. all the zeta potential of constant charge soils, i. e., yellow brown earth, brown earth,dark brown earth and black soil, in different electrolyte solutions were always negative in sign and no IEP occurred on zeta potential-pH curves.The shape of zeta potential-pH curves varied with soil type, electrolyte kind and pH. Canon adsorption caused the zeta potential of clay particles to change towards positive potential direction. The contribution,△ζ of canon specific adsorption to zeta potential of different soils were of the orders:K⁺2+2+2+2+ for laterite,and Ca²⁺<K⁺<Mn²⁺<Cu²⁺<Zn²⁺ for yellow brown earth and black soil.

Abstract:Charge amount, point of zero charge (PZC),point of zero net charge (PZNC),the relationships among the above surface charge properties, and the composition of 3 types of soil in central and southern China were studied. Results showed that: (1) From lateritic soil, red soil to yellow brown soil, the permanent negative charge amount (CECp) which chiefly relates to soil clay mineral composition tends to increase; whereas the variable negative charge amount (CECv) which mainly depends on Fe and A1 oxides content of the soils shows no obvious trends; the variable negative charge to total negative charge ratio and positive charge amount tend to decrease. (2) For the examined lateritic soil, red soil and yellow brown soil, PZC is 3.90, 3.35-3.50 and 2.96-3.12, respectively;PZNC for the examined lateritic soil and red soil is 3.85 and 2.15-2.84, respectively, For yellow brown soil, there is no PZNC.(3) Surface charge indexes of variable charge soils were suggested to be PZC>3.0, PZNC>2.0, PZC-PZNC<1.0 and CECv/CEC8.2>0.4 for the soils in central and southern China.

Abstract:Mn deficiency of wheat is a main problem of plant nutrition in Sichuan Province,which was considered to be relation closely with paddy-upland rotation. An experiment with model soil-column was conducted to study the characteristics of Mn movement and its uptake by rice (Oryza sativa L.) in two alluvial soils under different water and fertilization status.It was found that soil active Mn (easily reducible Mn) decreased while DTPA-Mn and exchangeable Mn increased as soil was waterlogged, which caused the Mn leaching through 1 meter soil column and its excessive uptake by rice plant. The total storage of available Mn thus decreased. The effect of water and fertilization on Mn followed the following the following sequence: CK>NPK and NPKM (the above treatments were waterlogged)>>Wetting with NPK fertilizer (NPKM/Wet). The sequence of DTPA-Mn and exchangeable Mn in soil layers (especially 0-20cm) was CK and NPK>NPKM>>NPKM/Wet>the original upland soil, but active Mn in soil was reverse. This phenomenon was more obvious in gray alluvial soil than in gray-brown alluvial soil. It showed that Mn is an active element which is easily affected by water and fertilization status, and wetting treatment can slow down the Mn transformation in soil and decrease the uptake of Mn by rice plant greatly. Therefore, to adjust the transformation of Mn in soil and its availability to plant through the management of water status woutd be practicable.

Abstract:The K supplying potential of 11 main soils in China was evaluated comprehensively with pot experiment of bio-depletion of soil potassium and chemical methods. Results were summarized as follows:stage of the minimum value appearance and amount of soil exchangeable K varied with soil type after soil potassium depletion. The soil exchangeable K also has "utilization ratio" or "availability degree".Its minimum value is one of the important characteristics of soil K supplying potential. As reaching the minimum value the non-exchangeable K increases again with the increase of the potassium depletion time, and finally, approaches or overtakes a level of pre-depletion. The results were suggested that potassium which could not be extracted by boiling in 1 mol/L HNO₃ was released largely and absorbed by plants mainly. It would not be mineral K but nonexchangeable K.The closest correlation between the soil available K extracted by cold 2mol/L HNO₃ and the content of K absorbed by plants was revealed by all of the test methods. The procedure of this method is simple and easy to operate. It is applicable to test soil K of upland and paddy field. The K supplying potential of 11 main soils of China were classified preliminary based on the content of soil available K and its minimum value.

Abstract:An isotope (15N) labelling technique was used to estimate the turnover of soil nitrogen through microbial biomass in red soils. The turnover times of soil nitrogen in microbial biomass were 251, 89,and 63 days, for the long-term cultivated red clayey soil (30 years of tea orchard),mid-term cultivated red clayey soil (4 years citrus orchard) and short-term cultivated red sandy soil (3 years upland),respectively. The annual fluxes of soil nitrogen through microbial biomass were 1.5 to 6 times of the microbial biomass nitrogen itself. The microbial turnover rate of soil nitrogen was closely related to the soil organic matter, and it was higher in sandy soil than in clayey soil. Obviously, microbial biomass turnover of soil nitrogen plays an important role in the availability, retaining and accumulation of soil nitrogen in red soils.

Abstract:In this paper, the research of regional sustainable development in Guilin City was carried out. The study included the following: 1)Prediction of the development and change of regional PRESD system factors and their relationships; 2) Evaluation of the sustainability of regional PRESD system development Results showed that in the regional sustainable development in Guilin City,some senous problems will be faced in the future. It is important to study and predict the factors affecting the regional sustainable development. Thus. land resources and their use were taken as core of the study on the regional Sustainable development which will promote sustainable development study into practice stage and enrich the research theories and methods. In the end of this paper, some countermeasures for regional sustainable development in Guilin City were put forward, and the methods in regional sustainable development research were discussed.

Abstract:Studies on phosphorus efficiency of native soybean (Glycine max (L.) Merrill) genotypes in Guangdong and relationship between phosphorus efficiency and content of soil available phosphorus of original region were conducted in low-phosphorus red soil.Results are as follows:(1) The field growing performance under low-phosphorus acidic red soil and the phosphorus efficiency of soybean genotypes can be explained better with Relative Value of Plant Phosphorus Uptake (RVPPPU) as an index. The higher the RVPPU of soybean genotypes is, the better the field growing performance and the phosphorus efficiency are, and vice versa.(2) Genetic variability in respect to phosphorus efficiency exists within soybean genotypes from different native region. As compared with those from soil and fluvo-aquatic soil with higher content of soil available phosphorus, soybean genotypes from latosol, lateritic soil,red soil and purple soil with lower availability of soil phosphorus have better characteristics of phosphorus efficiency in native regional soil where they had evolved for a long time.

Abstract:The soil microbial biomass carbon and nitrogen were measured in three long-term expenments,the different vegetation remediation experiment in red earth ecosystem, the experiment of red earth highland with different fertilization systems and the pollution experiment of Pacloutrazol and Chlordimeform, in the Red Earth Ecosystem Experimental Station, Academia Sinica. Results showed that soil microbial biomass could be sensible to indicate the effects of four types of vegetation on the bio-remediation of the degraded red earth ecosystem, to show the different effect of fertilization system on the fertility of red arable lands and to detect the pollution of Pacloutrazol and Chlordimeform applied to the red earth. Thus, the conclusion that soil microbial biomass may be as a bio-indicator of soil quality in the red earth ecosystem could be drawn.

Abstract:渍害是我国小麦生产的主要自然灾害之一,严重影响到小麦产量。其原因可能是渍水使得土壤氧亏缺,抑制了作物的生理代谢,改变了植物营养状况和土壤养分的有效性;或是由于较低的土壤氧化还原电位使得营养的吸收与累积下降^[1~3]。受渍小麦大多表现为功能叶早衰,绿叶数量及面积减少,光合速率和干物质积累下降^[4,5],最终影响作物产量和千粒重^[5,6]等;也有研究表明小麦的耐渍性与其基因型有关^[7]。本文主要从营养生理角度研究不同生育时期渍水对小麦氮、磷、钾吸收、运转与积累的影响;探讨不同营养元素在小麦不同生育时期受渍条件下的变化规律及其特点,为从营养调控上减轻小麦渍害提供必要的理论依据。

Abstract:有机物料的施用,影响着土壤的理化特性与生物性状,也必然影响植物的生长发育。植物与土壤直接接触区域是根际微域,要了解有机物料对作物生长发育的影响,必须先探讨其对根际微域的作用。研究与揭示很际微域环境状况对增加土壤养分供应,促进根系对养分吸收、改善树体营养状况及提高产量与品质等方面具有重要意义^[1]。果树根际微域的研究工作开展较少^[1,2],为此我们研究了两种有机物料对苹果砧木根际微域中土壤酶活性及元素有效性的影响。