Abstract:The origin of Quaternary red earth in Jiujiang and Taihe, Jiangxi Province had been discussed by comparatively studying on the forming environments, the particle-size distribution, the geochemical characteristics of REE and the morphological features of the quartz grains. The results showed that the Quaternary red earth in Jiujiang, located in the transitional zone between red earth and Xiashu loess, was aeolian origin, as it shared many aeolian features with Xiashu loess; however, that in Taihe, located in the Ji'an-Taihe Basin, was alluvial origin, with obvious alluvial features.

Abstract:The micro-structure of several typical redoxi-morphic features of Hydragric Anthrosols were analyzed by combining micro-morphological observation and Electronic Energy Disperse Spectrometer (EDS) determination of micro-zone chemical composition. Their formation mechanisms were suggested. The results showed that, root pore/fissure coating was formed through the enrichment of oxidized ferrous iron (Fe²⁺)on the surface of root pore or fissure, and the oxidation took place on the surface of Al-silicate clay mineral. The formation of rizospheric concentric iron-ring involved a self-organized process of reaction-transfer-reaction feedback, which leaded to the formation of banded iron-rich and iron-poor zones. Bleached coating can be separated as iron (and/or manganese)-depleted and clay-depleted ones, which were obviously different from each other in micro-structure and chemical composition. The later not only had more loss of iron and manganese but also was accompanied by destruction of Al-silicate clay.

Abstract:Estimation of hydraulic resistances of soil-plant climate continuum (SPAC) is important both for describing water movement in the continuum and for adopting practical water-saving measures in agriculture to find the solutions to seasonal drought in the area of Red Soil of China. The diurnal variation of stomatal resistance of crops in dry season was observed and its relation to transpiration rate and water potentials of crop leaf and soil in different farming systems was also studied. Results indicated that stomatal resistance and transpiration rate were different for each crop in different farming systems. Stomatal resistance was related to soil water potentials within the soil layers of 70cm. The hydraulic resistances of the leaf-air interface in SPACs ranged from 10⁹ to 10¹⁰ S, which was 1000 times higher than those of crop body. The resistance of crop body was 100 times as much as that within the soil layer of 70cm. In dry season, soil resistance increased with the depletion of soil water. Resistance of crop body fell in the order: soybean>peanut>corn>sweet potato, which experienced dramatically diurnal variation except that of sweet potato. Resistance of crop also varied with cropping systems.

Abstract:The soil responses to climatic changes are a key problem in the studies of global change. Soils in the past provide a valuable record for the understanding of the relationship between the soil and the climatic changes. Here we report a case study to the red earth section at Jiujiang City in southern China. This section is about 15m in thickness, and consists of two pedogenic units. The upper part is a layer of yellowish silty clay, while the lower part a layer of red clay with yellow and white worm-shaped veins. Mass-balance equations applied to geochemical analyses reveal that the degree of weathering increased down-section and the concentration of resistate constituents decreased upward. A pronounced depletion of bases(Na, K) has been shown in the lower part of the section. This weathering trend is not observed in the loess sections in northern China, and is probably the results of Quaternary climatic changes in southern China and of the variations in dust input resulting from the deterioration over central Asia.

Abstract:Diel and seasonal changes of carbon dioxide emission from Mollic-Cryic Cambisols on degraded grassland were studied. The results indicated that: (1) Diel maximum rate of CO₂ efflux appeared at 12:00-16:00 and minimum at 4:00-8:00. Rate of CO₂ efflux in the daylight was greater than that in the night. (2) There were significant seasonal dynamic and phenophase changes in rate of Cqemission. Diel average rate of CO₂ emission was 320.86±130.49mgm^-2h^-1.Phenophase variation was exuberance>withering>green up. (3) Diel change course of rate of CO₂ emission was controlled by air temperature and soil surface temperature. However, the correlations between seasonal dynamic of rate of CO₂ emission and air temperature, soil surface temperature, and temperature of each layer of soil (5cm, 10cm, 15cm, 20cm, 30cm) were very significant (P<0.01). (4) The rate of Cqemission from Mollic-Cryic Cambisols on the over grazing pasture is lower than that on the moderately grazing pasture.

Abstract:In the article, the relationship between the soil taxa and the soil forming factors is analyzed and its model is established on the basis of research on soil taxonomy in the selected region, GuiYang, GuiZhou Province. RS and GIS is applied to enhance and income the message of the soil forming factors, which are calculated by the method of overlying vector,and finally the map of soil taxonomy is achieved through the way of the model of soil taxa and soil forming factors. According to validating in the field, on the basis of TM, the method can meet the requests from 1:100 000 scale soil map.

Abstract:Studies on the compositional proportion of characteristic microaggregates of 15 pairs of fertile and infertile typical brown earth and brown earth type paddy soil were carried out. Results showed that the proportion of(<10μm)/(>10μm) microa-ggregates could be used as an integrative index for evaluation of their fertility levels. The critical value of this proportion is 0.25 and 0.35, respectively, for the typical brown earth and brown earth type paddy soil, i. e., the soil fertility is higher if the value is less, or otherwise. Soil improvement measures could decrease the compositional proportion of soil characteristic microaggregates, and increase the soil fertility.

Abstract:The effects of root system of corn, bean and wheat on the fractionation of copper, lead, cadmium and zinc in rhizosphere in farmland soil irrigated with wastewater were studied. It was revealed that the levels of exchangeable copper increased significantly in rhizosphere soil under influence of wheat, corn, or bean. For bean, metals bound to carbonate and Fe-Mn oxide decreased. No change in level of organic bound metals was detected. It is believed that the dominant transformation processes occurred in the rhizosphere were the transformation of carbonate and Fe-Mn bound metal to exchangeable fraction. The effect of root system of bean was much more notable than that of wheat and corn.

Abstract:In this study, Humic acids from soils with different fertilization were fractionated into seven fractions by alcohol precipitation technique, and the fractions absorption by Ca²⁺ saturated monhnorillonite was studied. The results showed that the absorption could be described by single surface Langmuir, double surface Langmuir and Freundlich equations. The change trends of absorption amount and strength were not consistent with the fractions number order. Of all the seven factions, fraction 4 or 3 had the largest absorption amount and strength, suggesting that fraction 4 or 3 was the optimum absortion fraction which had the optimum molecular state for absorption. Compared with no fertilizer and chemical fertilizer, the absorption amount and strength of the optimum absorption fraction of organic materials increased.

Abstract:It has been established that plant leaves and other above-ground parts are capable of absorbing chemicals and nutrients. However, there is scarce information regarding translocation and recovery rate of ion uptake via leaves during different growing stages. Urea has generally been found to be the least toxic and most effective form of N for foliar application becasuse of its nonpolar and undisociated characteristics. ¹⁵N-labelled urea combined with KCl or KH₂PO₄ was both applied on selected leaves of com and wheat at different middle-latter growing periods. The top dressing of ¹⁵N-labelled urea in sand culture of corn at silking stage was also investigated to compare the effects of different foliar and root top dressing on plant growth. The N input in leaves of both crops was remobilized rapidly to other organs. For summer corn, the transferred percentages into roots of ¹⁵N input in lower (the fifth leaf) and middle (the eighth leaf) leaf were 9.0% and 2.4%, respectively, at jointing stage. Recovery rate of leaf-input urea-¹⁵N in whole corn plant ranged in 59.9%-75.3%, while the rate in above-ground part of winter wheat was in 54.5%-68.9%. There was very similar tendency for the two crops that the ¹⁵N recovery rate taken up via leaves was apparently increased as delay of application period. Compared with urea feeding alone, combined foliar application of urea with KCI or KH₂PO₄ increased the recovery rate and improved the N nutritional status of whole plants, in which the optimum treatment for com was foliar feeding of urea plus KH₂PO₄ to middle leaf. Therefore foliar fertilization should also focus on balance supply, suitable application stage and leaf position. Foliar feeding of N or P and K fertilizer not only improved the corresponding nutrient status in plants, but also stimulated root uptake of the other two nutrients and increased translocation ratio of N and P to grain. The finally accumulated ratios of labelled urea-¹⁵N in grains top-dressed via the roots and leaves at Bilking period were 56% and 70%, respectively.

Abstract:8 red soils differing in fertility levels were tested to study the relationships between soil microbial biomass P and soil P or P plant availability. The results showed that red soil microbial biomass P was closely related with soil total P, soil organic P and soil rapidly available P. Relative coefficients were 0.840, 0.897 and 0.944, respectively. Especially, the significant relation of red soil microbial biomass P to soil rapidly available P suggested that red soil microbial biomass P may act as an indicator of P-supply ability. Greenhouse incubation expriments showed that red soil microbial biomass P was also closely related with ryegrass dry matter yield, ryegrass P uptake and P uptake per unit weight of ryegrass. Relative coefficients were 0.789, 0.895 and 0.910, respectively, which indicated that P plant availability of red soil microbial biomass P was not only reflected on ryegrass dry matter and plant P uptake, but also more obviously reflected on P uptake per unit weight of plant.

Abstract:A long-term plot experiment was conducted in the Sanjiang Plain to study the effect of applying organic manure for years in row on soil humus composition, transformations of Fe, Mn and Al oxides and phosphorus availability. The results indicated that soil humus, mainly loosely combined humus were increased after 4 years of adding cow feces, because of the supply of lowmolecule organic acid released from the added cow feces. The contents of DTPA-extractable and organo-chelated Fe, Mn, Al was also related to organic acid corroding soil coating and solublizing soil oxide. Some half-products derived from the fresh material can supply H⁺,and can chelate or solublize soil Fe, Mn, Al or compete for adsorption site on soil colloid, and form Fe, AI-OM-P or soil colloid-OM-compounds, thus bring about significant increase in soil available P. So the bio-measure is an effective strategy to ameliorate albic soil, enhance its nutrient, especially P, availability and its buffer capacity and stress-resistance.

Abstract:Some microelements, such as B, Mn, Fe, Cu, Zn, Mo, etc., are regarded as essential elements to both animals and plants. But applying fertilizer blindly to soils can cause both waste and environmental pollution. In this paper, 32 soil samples were collected and the environmental geochemical characteristics of the aforementioned 6 kinds of microelements were studied in the yellow brown soil, which has the largest distribution area in zonal soils of Hubei Province. The main results are as follow: (1) B, Mn, Fe and Cu are relatively high in total contents, but Mo is lower. The available B, Cu, Zn and Mo are all insufficient. (2) All the microelements are the highest in total content in the subsoil and the highest in available form in the epipedon. (3) The positive correlation between the contents of total and available Zn&Mo arrives to significance or extreme significance level. The posifive correlation between the contents of available B&Mo and pH of the yellow brown soil is proved to be of extreme significance. But for Fe&Zn, the negative correlation is also the same level.The contents of all available microelements except for Fe have significant of extreme significant positive correlation with the organic matter content in the soil. The authors think it necessary to plough deeply and apply organic fertilizer to improve the contents of available microelements in the yellow brown soil.

Abstract:To aim directly at problem of crop demanding boron in sustainable agriculture development of brown-red soil in the hilly region of south Hubei Province, the content, forms, distribution, annual change, runoff, leaching and balance of the boron were analyzed. On the base of the synthetic analysis, the simulation model of boron cycling was set up. The results showed that distribution, removing and cycling of boron in different type farmland were different in the typical catchment, the period of annual change of majority form boron is six months, the surface assembled of HWSB is obvious, but the vertical transfer coefficient of HWSB was different in different type farmlands, boron loss of runoff and leaching were affected by leaves area index and stable leaching ratio principally.

Abstract:In this paper, a heterogeneous soil column was constructed in our laboratory. The column contained two kinds of homogeneous soils, which were of different texture, and was successfully constructed in the Ⅲ-shaped cross-section distribution of sandy loamy and loamy clayey soil using special shape soil partition.The heterogeneous soil column (50cm×50cm×40cm) was irrigated with 0.027mol/L CaCl₂ solution till steady water flow in soil column occurred. The effluent was collected every 5 minutes. The data was simulated using transfer function model. The probability density functions of the logarithm of travel time of chloride were calculated, and the model parameters (i. e. mean and deviation) were obtained. In addition, the transport volumes of chloride, the volume-averaged resident concentrations of chloride in the soil solution and other parametric values were obtained. To make a comparison between the deterministic and stochastic models, the breakthrough curves in homogenous soils were also plotted and simulated by the convection-dispersion equation.

Abstract:This paper addresses organic matter content, sition of humus, content of O-containing functional group and infrared spectrum characteristics of humus in salt affected soil under different age of amelioration at the Quzhou Experimental Area in Hebei Province. The results of the experiment show that with increasing age of soil amelioration and improving fertilization and cultivation levels. The quantity and quality of soil organic matter in the salt affected soil improved steadily from the first generation to the second generation and the third generation of experimental area successively which is demonstrated by the increases in content of total humus, HA/FA ratio, and content of functional group, and decrease in E₄₆₅/E₆₆₅ rate. There are indications in the results of the infrared spectrum analysis that the soil humus was a complicated system of multi functional groups. The type of HA had changed from Rp to B type from saline land to the first generation of experimental area, indicating that the soil humns was developing forwards complicated structure and diversified function. The content and quality of the organic matter in the ameliorted salt affected soil have approached to the level of the local non-salt affected soil-bright meadow soil.

Abstract:热带亚热带土壤中存在着性质活跃且含量较高的氧化铁和氧化铝,其对土壤的物理、化学及肥力性质等有着深刻的影响,由于它们带有大量的可变电荷而使其行为在土壤表面电荷性质的研究中倍受关注^[1～6]。就氧化铁对土壤表面电荷性质的影响,一些学者采用DCB处理脱去土壤中游离铁的方法,将处理后土壤表面电荷性质的变化归结为游离铁的作用^[1～3]。事实上,DCB对土壤的提取液中,存在着一定数量的氧化铝,因此,“DCB提取的游离铁”对土壤表面电荷的影响应视为“DCB提取的游离铁和部分氧化铝”的共同作用。

Abstract:山东省旱地大多瘠薄,土层厚度对旱地小麦产量尤为重要,土层越厚,其保水保肥效果就越好^[1]。1996-1997年度山东莱阳旱地小麦经省实打验收,实打面积1.65亩(1 hm²=15亩),其土层厚度在200cm左右,创亩产693.64kg。为了探讨土层厚度对旱地小麦氮素分配利用及其产量的影响,我们设计了此项试验,以期为旱地小麦高产高效制定合理的管理措施。

Abstract:泥沙问题是黄河治理的关键,而黄河泥沙主要来源于中游黄土高原强烈的水土流失。在黄土高原,耕地水土流失面积占耕地总面积的71.3%^[1],其中坡耕地土壤流失量可占流域土壤总流失量的60%～70%^[2]。水土流失时,土壤中的养分会随径流及侵蚀泥沙迁入水体^[3],使细颗粒泥沙发生絮凝或分散,而流失泥沙中细颗粒泥沙含量又往往高于耕层。细颗粒泥沙的絮凝或分散,对泥沙输移和沉积过程有重要作用,是造成水库、灌溉渠系以及港湾河口淤积的重要原因,也是研究高含沙水流、浑水淤灌,以及设计冲沙模型的基础^[4]。同时, 侵蚀径流中细颗粒泥沙的絮凝或分散也会影响表土的导水率,从而影响水土流失量^[5,6]。

Abstract:农业的持续发展依赖于土壤的持续利用,而土壤的持续利用要求土壤肥力的维持和提高。为维持和提高土壤肥力,目前我国采取的主要措施之一是秸秆还田。秸秆还田的方式有两种^[1],一是直接还田,包括翻压和地表覆盖两种方式,二是沤制后还田。不同的还田方式增肥的效果不同^[2,3],由于沤制后还田费时费工,采用的较少,目前一般采用直接还田方式。由于翻压和覆盖还田所处的土壤条件不同。秸秆腐解速度也不同,对土壤养分积累也不同。本文主要就秸秆还田的不同深度对秸秆腐解速度的影响展开讨论,从中探讨出最适宜的还田深度。

Abstract:磷素在农业生产中是不可缺少的。包括土壤成土矿物、氧化物等在内的土壤固磷介质对磷有明显的固定作用。