Abstract:243 soil profiles in Hainan Island were identified and classified according to Key to Chinese Soi Taxonomy (3rd edition), and the relation between topographic-lithologic units and soil taxonomic taxa was discussed Then, based on the summarized correlation between units and taxa, the tentative draft on soil mapping units of Hainan Island according to Chinese Soil Taxonomy was drawn up and the sketch maps of soils on some selected plots were made The total of mapping units to be set up are fifty throughout the Island It was found that the procedure used in this study to compile the soil map with Chinese Soil Taxonomy system is easier to operate and more objective than the procedure which simply changed soil type name on the former soil map with Soil Genetic Classification system.

Abstract:On the basis of field investigation and laboratory identification and analysis, the large-scope migration of desert-steppe in Loess Plateau about 450 ka BP was discussed. The data show that gypsum, represent desert-steppe environment developed in the early stage of the fifth loesss format ion in Shaoling tableland of Chang an and Bailu tableland of Xi'an on the southern edge of Loess Plateau, which shows that remarkable drying of climate and large-scope climatic migration toward south occurred in the area at that time, and climate zone migrated about five degrees in latitude, and desert-steppe and more wild environment distributed widely in Loess Plateau. The development of gypsum also shows that climate changed from monsoonal climate to non-monsoon climate in Loess Plateau, which was a change in character, and this area had been not effected by summer monsoon, and in the early stage of the fifth loesss formation, was in non-monsoon climate environment at that time.

Abstract:‘Soil water reservoir' was defined as a space that reserve and transport the soil water in the soil, and total pore space of the soil as maximum available volume of the reservoir. The volume of pore space and the water transportation capability of soil are two of the important reservoir characteristics. In this paper, the efficiency of the ‘soil water reservoir' on flooding control were studied by simulator rainfall in the south of China with 5 typical ecological patterns of red soils, such as sparse wood (Ⅰ), wood-grasses (Ⅱ), grasses-brushwood (Ⅲ), economic orchard (Ⅳ), crop land (Ⅴ), and bare land (Ⅵ) as contrast. Water balance factors of soils were measured and estimated respectively in the experiments, such as rainfall (P), water in-come (F), water reserved (W) in soil, water discharged (D), surface runoff (R) and soil maximum saturated infiltration (F'). Results show that a main obstructive factor resulted in that ‘soil water reservoir' decreased the capacity of flooding control in the red soil area, is that the channel, through which water come into soil, was blocked or partly blocked. The grasses-brushwood (Ⅲ) is the most efficient one of 5 patterns to control flooding, the economic orchard (Ⅳ) pattern is suggested to be used in the area as the first one in sequence because of not only with higher efficiency of flooding control but with higher economic benefits. It is necessary to improve the efficiency of soil's flooding control in the area by protecting wood grasses and brushwood grasses from damage, recovering wood and grasses land from crop, increasing degree of surface grasses-cover in the sparse wood. The results also show that the soil water reservoir theory is available to be used to assess the flooding control function of soils. Capabilities of the ‘soil water reservoir', including soil water reserve and water transport, are most important when we study on ‘soil water reservoir' to control flooding. How to increase soil infiltration? It is a key to improve efficiency of the reservoir on control flooding.

Abstract:The paper shows that characteristic, trend and driving forces of quantity change of cultivated land and the disciplinarian of balance between supply and require for cultivated land under food supplies safety long-term in the developed region by the analyses of relation between change of cultivated land and humanity factors near 20 years in Jiangsu. The results indicates that descending rate of cultivated land in the developed province is more eighteen percent than the mean value of whole country, that extent of cultivated land use change presented diversity like terraced or radiation state which is becoming diminutive from the much more developed region to the general developed region, and that driving forces of cultivated land change are economy increase, society progress, the advancement of science and technology, security of food, policy, market, and the safety of environment etc. The descending trend of cultivated land in quantity endanger the balance between supply and demand and the security of food within the period of too many population, therefore we should take effective measures to prevent it as fellow: the protection of farmland, the construction of land-use system and the ownership of land in the country, the avoidance of police' misdirection, saving on land-use, the protective development and study on land resource in supporting, and the fallow of cultivated land in the regulation of agricultural structure.

Abstract:A study on micromorphology of aridosols in the plain of the south of Xinjiang and origin of parent materials was carried out in this paper by means of field investigation, scanning electric microscope, polarizing microscope, physical and chemical analyses. The results are as follows: Aridosols in the plain of the south of Xinjiang consist largely of sandy primary minerals composing skeleton. Among the sandy primary minerals there are a mass of plasmas made up of fine silty primary mineral, cryptocrystalline and microcrystalline carbonate, and clay. A majority of primary minerals keep intact appearance. From the surface to the bottom horizon skeleton increases and plasma decreases. The aridosols in the plain of the south of Xinjiang have porphyroskelic fabric, agglomeratic fabric and bleached sand fabric. pedological features of aridosols in the plain of the south of Xinjiang are iron, carbonate and gypsum concentrations. The shape of carbonate and gypsum relates to its content. The aridosols in the plain of the south of Xinjiang contain a great quantity of the carbonate in the shape of interflorescences, cutans, nodules, clots and autogenous calcite and accumulates an abundance of gypsum in the form of cryptocrystalline, microcrystalline, needle-shaped, spindle-shaped fibrillar crystals. In ferri-argillic horizon, clay and silt become more and iron concentrations exist in the form of the matrix stained by iron. Quartz grain surface textures indicate: parent material of aridosols in the plain of the south of Xinjiang moved a short distance, and was affected by several factors, especially wind.

Abstract:Study results showed it possible to analyze quantitatively pore variability in small scale and pore complexity in various soils under different treatments by using the method of digital image. Pore has high variability on 2mm scale as well as high complexity. Pores showed the shapes of various networks in the recon structed soils while showed the shapes of irregular branches or ellipses. There are discrepancies of various extents in pore perimeter, porosity, variability and complexity in different soils under different treatments.

Abstract:To analyze and simulate water flow and solute transport in the soil media, conduct catchment hydrological process simulation and optimize related agricultural activities, it is important to understand three-dimensional distribution characteristics of soil water and its temporal variability In this study, by densely installed electrodes at a 3.5m×3.5m square in the field, first, soil resistances were measured at a given time interval Then, based on an inversion algorithm for soil real resistivity and a relationship between soil resistivity and water content, three-dimensional spatial distributions of soil water content were obtained Finally, on the basis of an analysis about the soil water content, three-dimensional spatial distribution characteristic of soil water and its temporal stability were investigated The results show that the spatial distribution of soil water content at the experimental site is heterogeneous and anisotropic However, this heterogeneity is not a random process; it has a spatial distribution pattern This distribution pattern remains the same before and after the rainfall, indicating temporal stability of the spatial distribution characteristics of soil water.

Abstract:Engineering measures, and reasonable and stereoscopic collocation of shrub-grass vegetation were performed over on large tracts of barren hills and slopes. The results showed that in the forth growth year, the root system of Prunus davidiana reached 320~360 cm deep, soil water content in the soil layer 0~500 cm deep decreased by 2.1%~3.3% compared to that before reforestation and the thickness of dry soil layer was 150 cm. And in the eighth growing year, the roots distributed as deep as 480 cm, the dry-layer reached 300 cm in thickness, the lowest and highest soil water content was 4.2% and 8.4% respectively. And in the twelfth year, the dry soil layer became very distinct, reaching 350 cm in thickness, and, especially in the 50~400 cm soil layer, the lowest and highest soil water content was 5.0% and 8.6%, respectively. While in the sixteenth year, the dry soil layer distributed in the depth of 50~350 cm, and its thickness was 300 cm, with the lowest and highest soil water content reaching 4.3% and 6.6%, respectively. But by building leveled terrace fields, contour ditches and fishscale pits, soil water content increased by 0.7%~6.3% in the depth of 0~100 cm, 0.6%~4.6% in 100~300 cm and 1.4%~4.6% in 300~500 cm compared to that in the barren hill, respectively. It showed that applying reasonable combined measures plus afforestation could regulate soil moisture region with significant effect.

Abstract:Field experiment was conducted to investigate root distribution of winter wheat and the spatial avai-lability of soil water and nutrients under different irrigation strategies: High frequency with low amounts (HL) and low frequency with high amounts (LH). The results showed: HL decreased root growth in topsoil after regreening, but reduced root decline after shooting, while LH increased root growth in topsoil but root decline was higher after shooting. Furthermore, in subsoil layer (30~60 cm) root biomass and root length density of LH were higher than those of HL. Change of soil moisture was solely resulted from irrigation. Also irrigat ion caused nitrate-N to move down, in the three treatments, not out of 0~60 cm root zone. However irrigation had no effects on available P and K distribution in soil profile during wheat growth. The difference of root distribut ion in soil did not affect water uptake. Due to insufficient water stored in soil before sowing, available water of soil (0~90 cm) was depleted after harvest. Furthermore different root length density in upper and middle layer did not affect nutrient uptake in those layers. It was dry in the topsoil after flowering that affected nutrient uptake. Due to irrigation after flowering HL increased not only grain milking but also nutrient accumulation of grain. Winter wheat growth, development and nutrient uptake among three treatments had no difference before flowering. After flowering insufficient water supply of LH and LW affected grain milking, which cause decrease in kernel weight and yield.

Abstract:A field study was conducted to investigate effects of leguminous green manure and chemical fertilizer N on nitrous oxide (N₂O) emissions from paddy soils under double-crop rice systems. Results demonstrated that during the early rice growing season, the treatment that received both green manure and synthesized N fertilizer emitted significantly more N₂O than the other three treatments did, which received only green manure (V0), only synthesized N fertilizer (FN), or neither green manure nor chemical N fertilizer (F0), separately. The seasonal accumulative N₂O-N emission was 2.75 kg hm^-2 with the former, and 0.29 kg hm^-2, 0.35 kg hm^-2 and 0.18 kg hm^-2, respectively with the other three. During the late rice growing season, 0.34, 0.26, 0.28 and 0.23 kg hm^-2 was emitted from those four treatments respectively, all much lower than that from Treatment VN during the early rice growing season. Besides its effect on N₂O emission rate, the incorporation of green manure also affected N₂O emission time pattern. In Treatment VN, N₂O evolution was concentrated mainly after the midsummer drainage during the early rice growing season, while in the other three treatment the N₂O emission was distributed evenly throughout the entire rice growing season. The results also indicated that there existed great interaction between green manure and chemical N fertilizer during the early rice growing season.

Abstract:A new concept of Effective Nutrient Soil Areas (ENSA) was put forward and studied with the regression method. Through conducting experiments with corn and sugar beet, a model of the relationship between ENSA and yield of an individual crop was established. By using the model, an optimal ENSA of corn was worked out as 0.335 m² (57.9 cm×57.9 cm) and that of sugar beet as 0.358 m² (53.4 cm×67 cm). Therefore, for corn and sugar beet the ridge planting method of 67~70 cm in spacing, which is applied widely in the current production, is wasting soil resources, because the plant has a space larger than the ENSA of the crop. The results of the narrower space tests with the new theory show that their yields are about 19.8% higher than those of the normal ridge planting method.

Abstract:With root partition method and ¹⁵N-isotope dilution method, field and pot experiments were conducted to examine the research included the effects of intercropping of rice cultivated aerobic soil and ground nut on dry matter production, quantity of nitrogen uptake, biological nitrogen fixation, and nitrogen transfer from groundnut to rice at three nitrogen level, namely 0, N 225 kg hm^-2, N 300 kg hm^-2. Soil nitro gen fertility was also investigated under the new cultivation system. The results show that 1) there was a yield advantage in the new intercropping system compared to monocrop rice. The dry matter, for example, of rice in intercropping at three nitrogen application rates were 30.03%, 10.1%, 2.2% higher than those in monocropping, respectively, and the same situation happened for the nitrogen uptake. 2) Biolog ical nitrogen fixation estimated by ¹⁵N-isotope dilution method in groundnut decreased with the increase nitrogen level while intercropping can improve biological nitrogen fixation of groundnut. 3) N-transfer from groundnut to rice was evident but no co-relation between biological nitrogen fixation and nitrogen transfer was found in this experiment. 4) Intercropping system could increase significantly the mineral nitrogen during the whole growth stage, thus improving soil nitrogen fertility.

Abstract:Under a long-term experiment on different fertilization treatments, the contents of water-soluble organic carbon (WSOC) in the soil ranged from 32.1 to 45.5 mg kg^-1, following the order of NPK+4500 kg rice straw>NPK+2250 kg rice straw>CK>NPK. The percentages of WSOC to total soil organic carbon (TOC) ranged from 0.15% to 0.19%, following the order of NPK+4500 kg rice straw≈CK>NPK+2250 kg rice straw>NPK. The contents of WSOC had significantly positive correlations with both TOC and soil microbial biomass carbon(SMBC). ¹³C-NMR results showed that WSOC were mainly com posed of carbohydrates carbon, carboxyl carbon and long-chain aliphatic carbon. Under different fertilization treatments, the coefficients of variation (CV) of WSOC/TOC and SMBC/TOC were lower than those of their absolute contents in soil. Furthermore, the CV of WSOC/TOC was higher than that of SMBC/TOC. The percentage of WSOC to TOC was a good indicator of the quality of soil organic matter under different fertilization treatments.

Abstract:Effects of organic acids on Cd desorption from Cd-saturated soils and contaminated soils were studied. Results show: The desorption rate of Cd for three Cd-saturated soils and three contaminated soils could be characterized by valley-like curves with increase in tartrate or citrate concentration. Desorption rate of Cd was higher under the effect of citrate than under the effect of tartrate when concentration of the organic acids was higher than 2 mmol L^-1. Effects of tartrate and citrate on Cd desorption varied with the initial soil pH value. With increase in initial pH value from 2 to 8, Cd desorption rate for Cd-saturated soils and contaminated soils under citrate declined first, then rose, then declined again, forming a curve appearing like a lying "S". During the course a valley and a peak appeared clearly when the concentration of citrate was at 6 mmol L^-1. Under the effect of tartrate Cd desorption rate decreased with increase in initial pH value from 2 to 8. With higher electrolyte concentration, the desorption rate of Cd increased, moreover, Cd desorption rate with KCl electrolyte was higher than that with KNO₃ electrolyte under the same electrolyte concentration. What is more, effects of organic acids on Cd desorption remained more or less the same regardless of forms and concentrations of Cd in Cd-saturated soils and contaminated soils, initial pH value and type of electrolytes. From the results of this study, it could be concluded that avail ability of heavy metals was inhibited when concentration of organic acids was low. Contrarily enhanced availability would be found when higher concentrations of organic acids existed. So it is feasible to control the efficiency of bioremediation and phytoremediation for heavy metal contaminated soils by using different types of organic acids under varied conditions.

Abstract:A laboratory incubation experiment was conducted to evaluate the influence of accompanying anions on microbial activities in red soils polluted with cadmium. The results indicated application of cadmium as cadmium acetate markedly inhibited the soil microbial biomass, basal respiration, urease and acid phosphatase activity compared to cadmium applied as cadmium chloride at all cadmium levels. T-test showed that soil microbial biomass, basal respiration, urease and phosphatase activity were significantly different between red soils contaminated with cadmium acetate and chloride except for the metabolic quotients (qCO₂) in red clayey soil. Similarly, there were significant effects of cadmium with different anions on available cadmium contents in red soils after incubation. The available cadmium contents in red soils polluted by cadmium acetate were more than those by cadmium chloride. Another laboratory incubation experiment was carried out to argue the effect of associated anions on microbial activities in red soils added with potassium both acetate and chloride. Its results demonstrated that accompanying acetate anion can enhance soil microbial activities, but associated chloride anion has no remarkable effect on soil microbial activities. Thus it can be seen that difference of available cadmium contents which were resulted in by accompanying anions could be one of factors determining their relative toxicity to the soil microbial activities.

Abstract:Surface charge of inorganic colloids in soils(brick red soil, red soil, brown yellow soil, dark brown soil, black soil) distributed in different latitudes of China was studied with the back titration method and Mehlich method. Results show that: (1) a big difference exists between the two methods, mainly because they are based on different measuring units, but anyway they reflect surface charge of inorganic colloids from different sides; and (2) either has its own advantages. When used for determination of surface charge of inorganic colloids, however, both of them have to be modified in terms of practical procedure in determination.

Abstract:The relationship between the concentration of dimehypo and soil urease activity parameters was studied in this paper. The results showed that the characteristics of soil urease had remarkable divergence among the tested soils from different ecological zones. Dimehypo inhibited soil urease activity very significantly and the characteristic parameters of soil urease, such as its activity, maximum reaction velocity V_max, V_max/K_m and velocity constant kexcluding K_m, were decreased with increasing dimehypo concentrations. The correlation of urease activity and dimehypo concentration was in very significant level with few exceptions. To a certain extent, urease activity can be used as an index to characterize the soil polluted by dimehypo. The enzymatic reaction mechanism was mixed-inhibitory between soil urease and dimehypo. It was concluded from ED₅₀ values that the high content of organic matter as well as total N and total P alleviated the ecological toxicity of dimehypo in soils.

Abstract:In order to assess extents of the influences of soil properties on enzyme activities the relations between activities of urease, invertase and phosphatase and soil properties were studied through path analysis of twelve soil samples of the five major soil types in Zhejiang Province. The results showed that soil organic matter, total nitrogen, and total phosphorus were the major factors influencing activities of urease, invertase and phosphatase, while CEC had the least influence on them. With respect to direct effect in the path analysis, pH value most significantly influenced activities of urease and activities of invertase and phosphatase as well. But the direct effects of pH on the urease, invertase and acid phosphatase were to a large extent counteracted by the indirect effects of other factors on them. Silt also significantly influenced the activities of invertase, whereas clay and sand had certain influence on acid phosphatase and urease, respectively, but mostly in the form of direct effect.

Abstract:The soil acidity affects soil nutrients. Sampling in Dinghushan monsoon evergreen broad-leaved forest, we find: (1) The pH values of all soil layers(0~20 cm, 20~40 cm, 40~60 cm) in Dinghushan monsoon evergreen broad-leaved forest are below 4.5. (2) The concentrations of all nutrients in soil samples analyzed decrease with the depth of the soil profile. Except for hydrolytic N, the concentration of available P, available K, exchangeable Ca and exchangeable Mg are all very low. (3) The nutrients in 0~20 cm soil layer are more easy affected by soil acidity than other soil layers. In 40~60 cm soil layer, the concentration of nutrient are not markedly correlative with soil acidity except for Ca. In January and April, the soil nutrients are more easily affected by soil acidity than in July and October. As for nutrient type, the content of exchangeable Ca, exchangeable Mg and available P are more significantly correlative with soil acidity than other nutrients.

Abstract:Changes in soil organic matter has important impacts on soil fertility and CO₂ concentration in the atmosphere. It is established that models based on the computer simulation of the turnover of soil organic matter provide a useful approach to predict long term changes in the content of organic matter in soil. This paper briefly introduces overall development in modeling the turnover of soil organic matter and the special features of the widely used models (e.g. RothC and CENTRURY) in constructing techniques and uses. We mainly discussed the main principles applied to develop computer model for simulating the turnover of soil organic matter, including the model structure and main processes, the main affecting factors consid ered, and methods to evaluate the simulating and predicting results. The likely problems and further studies required were also outlined.

Abstract:非点源污染包括城市和农业非点源污染等。在城市工业点源污染逐渐得到控制后,城市非点源污染的研究也日渐成为热门课题,并取得不少研究成果^[1～5]。由于城市地表大部分为不透水面,降雨落到地面后迅速形成径流,并冲刷和挟带地表污染物形成地表径流污染。据文献报道^[3],城市降雨径流中含有悬浮物、耗氧物质、富营养化物质、有毒物质、油脂类物质等污染物,并在很多时候超标严重,这些污染物随径流通过排水道排入或直接进入江河湖泊,污染地表水。美国国家环保署(EPA)把城市地表径流列为导致全美河流湖泊污染的第三大污染源^[6]。城区降雨径流污染与其它非点源污染形式相比,在产污、产流特征等方面有很大区别。本文对此展开初步研究,试图揭示城区降雨径流的污染规律。

Abstract:根系吸水是陆地高等植物赖以生存的基础,其吸水能力是决定蒸腾和植株水分状况平衡的关键,而其吸水能力的大小取决于导水率的大小,因此根系导水率(Root hydraulic conductivity)成为研究水分在SPAC传输中的热点。关于环境因素对根系吸水的影响有不少报道,如干旱^[1]、温度^[2]、土壤通气状况^[3]都影响根系导水率。缺N、P降低小麦根的导水率^[4];缺S降低大麦根的导水率^[5];N、P、S有利于水孔蛋白的形成或提高水孔蛋白的活性^[6]等等。土壤容重是土壤的一项重要特性,它与土壤其它特性如土壤硬度直接相关,土壤容重提高,土壤硬度也增大。

Abstract:细菌在土壤中的运移与农业、工业、环保、水资源保护等领域密切相关。从地下水的细菌污染、垃圾处理、污水灌溉到细菌对有机污染物的携带运移、根层病害的生物防治、原位生物修复和污染物的生物降解、提高采油量和冶炼率等,都与细菌的运移和吸附密切相关。因此,人们对细菌在土壤中的运移进行了大量试验研究^[1,2],如发现土壤颗粒的特性、土壤溶液的组成、离子强度、pH等都影响细菌在土壤中的迁移;建立了数学模型来定量描述菌在土壤中的运移^[3~5],其中绝大多数是以对流-弥散为基础考虑吸附和解吸过程的机理模型。但Bai等^[5,6]认为细菌在土壤中运移时还存在不可逆的滤除过程,并用一级动力学反应来表示该过程。

Abstract:氮肥对作物增产作用巨大,但如果氮肥用量过大,则不仅增产效果甚微,而且造成氮素流失,并导致环境污染^[1～3]。目前浙江省耕地238万hm^2[4],平均年氮肥用量(N)300kghm^-2,每年纯氮流失总量达1993×10⁷kg(折合标氮100×10⁷kg)(1)。本文利用水稻生长模拟优化施肥^[5]、农业技术经济学的边际收益分析和环境经济学原理^[6],研究水稻氮素的适宜施用量,以期指导当前浙江中部地区的水稻生产。

Abstract:为高效持续利用海水与滨海盐土资源,缓解海水养殖废水直接排放对海洋的污染,课题组从1995年开始,收集、引进和筛选了一些具有经济开发前景的耐盐植物,对其生物学、生态学特性进行了研究[1],并在我国海南乐东、江苏大丰、山东莱州三个典型气候带海涂进行海水灌溉试验,探索海水灌溉对耐盐植物生长发育、滨海盐土演变的影响及其对海水养殖废水的净化能力。本文仅就山东莱州田间小区海水灌溉鲁梅克斯(Rumexpatientiax R.Tianschanicus,cv.Rumex K-1)的试验结果进行讨论。

Abstract:随着人们生活水平的提高和城市化进程的加快,美化城市和改善环境的森林景观日益受到重视。近年来,深圳市通过改造生态效益和美化效果不佳的人工林和退果还林,大力发展兼顾生态功能和景观效果的生态风景林,以便城市的生态环境与现代化建设相匹配,使其形象融合于幽雅的环境之中。土壤是树木赖以生存的基础。维持土壤肥力、实现林地可持续经营是森林生态效益的重要内容。选择生长迅速、改良土壤和美化效果好的树种是当前生态风景林建设亟待解决的问题。林分对土壤的影响已有报道^[1～6]。各树种的生长速度、凋落物性质和根系分泌的有机物质不同,导致其土壤肥力有差异。我们在退果还林地上营造了多种景观效果好的阔叶树种,探讨各树种的生长情况及其土壤肥力特征, 从树种的生长速度和改善土壤肥力的角度为生态风景林的树种选择提供理论依据。