石灰土壤原状土柱上硼和锌的迁移

Leaching of boron （B） and zinc （Zn） can be significant in some pedomorphic conditions, which can cause contamination of shallow groundwater and economic losses. Boron and Zn adsorption and transport was studied using 8.4 cm diameter × 28 cm long intact columns from two calcareous soil series with differing clay contents and vadose zone structures： Lyallpur soil series, clay loam （fine-silty, mixed, hyperthermic Ustalfic Haplargid）, and Sultanpur soil series, sandy loam （coarse-silty, mixed, hyperthermic Ustollic Camborthid）. The adsorption isotherms were developed by equilibrating soil with 0.01 tool L^-1 CaCl2 aqueous solution containing varying amounts of B and Zn and were fitted to the Langmuir equation. The B and Zn breakthrough curves were fitted to the two-domain convective-dispersive equation. At the end of the leaching experiment, 0.11 L 10 g L^-1 blue dye solution was also applied to each column to mark the flow paths. The Lyallpur soil columns had a slightly greater adsorption partition coefficient both for B and Zn than the Sultanpur soil columns. In the Lyallpur soil columns, B arrival was immediate but the peak concentration ratio （the concentration in solution at equilibrium/concentration applied） was lower than that in the Sultanpur soil columns. The breakthrough of B in the Sultanpur soil columns occurred after about 10 cm of cumulative drainage in both the columns; the rise in effluent concentration was fast and the peak concentration ratio was almost 1. Zinc leaching through the soil columns was very limited as only one column from the Lyallpur soil series showed Zn breakthrough in the effluent where the peak concentration ratio was only 0.05. This study demonstrates the effect of soil structure on B transport and has implications for the nutrient management in field soils.     

非饱和土壤一维水分入渗与再分布的解析解法

Soil infiltration and redistribution are important processes in field water cycle, and it is necessary to develop a simple model to describe the processes. In this study, an algebraic solution for one-dimensional water infiltration and redistribution without evaporation in unsaturated soil was developed based on Richards equation. The algebraic solution had three parameters, namely, the saturated water conductivity, the comprehensive shape coefflcient of the soil water content distribution, and the soil suction allocation coefficient. To analyze the physical features of these parameters, a relationship between the Green-Ampt model and the algebraic solution was established. The three parameters were estimated based on experimental observations, whereas the soil water content and the water infiltration duration were calculated using the algebraic solution. The calculated soil water content and infiltration duration were compared with the experimental observations, and the results indicated that the algebraic solution accurately described the unsaturated soil water flow processes.     

Salt-Water Dynamics in Soils: II. Effect of Precipitation on Salt-Water Dynamics

Through a simulation test carried out with soil columns (61.8cm in diameter),the effect of precipitation on salt-water dynamics in soils was studied by in-situ monitoring of salt-water dynamics using soil salinity sensors and tensioneters.The results show that in the profile of whole silty loam soil,the surface runoff volume due to precipitation and the salt-leaching role of infiltrated precipitation increased with the depth of ground water;and in the profile with an intercalated bed of clay or with a thick upper layer of clay,the amount of surface runoff was greater but the salt-leaching role of precipitation was smaller than those in the profile of whole silty loam soil.In case of soil water being supplemented by precipitation,the evaporation of groundwater in the soil columns reduced,resulting in a great decline of salt accumulation from soil profile to surface soil.The effect of precipitation on the water regime of soil profile was performed via both water infiltration and water pressure transfer.The direct infiltration depth of precipitation was less than 1m in general,but water pressure transfer could go up to groundwater surface directly.     

湿地土壤NH4+吸附解吸对冻融循环的响应

Nitrogen (N) cycling in boreal peatland ecosystems may be influenced in important ways by freeze-thaw cycles (FTCs).Adsorption and desorption of ammonium ions (NH + 4) were examined in a controlled laboratory experiment for soils sampled from palustrine wetland,riverine wetland,and farmland reclaimed from natural wetland in response to the number of FTCs.The results indicate that freeze-thaw significantly increased the adsorption capacity of NH + 4 and reduced the desorption potential of NH + 4 in the wetland soils.There were significant differences in the NH + 4 adsorption amount between the soils with and without freeze-thaw treatment.The adsorption amount of NH + 4 increased with increasing FTCs.The palustrine wetland soil had a greater adsorption capacity and a weaker desorption potential of NH + 4 than the riverine wetland soil because of the significantly higher clay content and cation exchange capacity (CEC) of the riverine wetland soil.Because of the altered soil physical and chemical properties and hydroperiods,the adsorption capacity of NH + 4 was smaller in the farmland soil than in the wetland soils,while the desorption potential of the farmland soil was higher than that of the wetland soils.Thus,wetland reclamation would decrease adsorption capacity and increase desorption potential of NH + 4,which could result in N loss from the farmland soil.FTCs might mitigate N loss from soils and reduce the risk of water pollution in downstream ecosystems.     

土壤水流通量对饱水带溶质运移参数的影响

The transport processes of solutes in two soil columns filled with undistrubed soil material collected from an unsaturated sandy aquifer formation in Belgium subjected to a variable upper boundary condition were identified from breakthrough curves measured by means of time domain reflectometry(TDR),Solute breakthrough was measured with 3 TDR probes inserted into each soil column at three different depths at a 10 minutes time interval.In addition,soil water content and pressure head were measured at 3 different depths.Analyteical solute transport models were used to estimate the solute disperison coefficient and average pore-water velocity from the observed breakthrough curves,the results showed that the analytical solutions were suitable in fitting the observed solute transport,The dispersion coefficient was found to be a function of the soil depth and average proe-water velocity,imposed by the soil water flux.the mobile moistrue content on the other hand was not correlated with the average pore-water velocity and the dispersion coefficient.     

土壤地下渗滤法处理分散生活污水的新技术: 两段厌氧土壤渗滤沟系统

The low removal efficiency of total nitrogen （TN） is one of the main disadvantages of traditional single stage subsurface infiltration system, which combines an anaerobic tank and a soil filter field. In this study, a full-scale, two-stage anaerobic tank and soil trench system was designed and operated to evaluate the feasibility and performances in treating sewage from a school campus for over a one-year monitoring period. The raw sewage was prepared and fed into the first anaerobic tank and second tank by 60% and 40%, respectively. This novel process could decrease chemical oxygen demand with the dichromate method by 89%-96%, suspended solids by 91%-97%, and total phosphorus by 91%-97%. The denitrification was satisfactory in the second stage soil trench, so the removals of TN as well as ammonia nitrogen （NH4^＋-N） reached 68%-75% and 96% 99%, respectively. It appeared that the removal efficiency of TN in this two-stage anaerobic tank and soil trench system was more effective than that in the single stage soil infiltration system. The effluent met the discharge standard for the sewage treatment plant （GB18918-2002） of China.     

钾和碳氮比对铵态土壤转化过程的影响

Two soils, one consisting of 1：1 clay minerals at pH 4.5 and the other containing 2：1 clay minerals at pH 7.0, were used to estimate the conversion of added NH4^＋ under different C/N ratios （glucose as the C source） and the addition of potassium. Under lower C/N ratios （0：1 and 5：1）, a large part of the added NH4^＋ in the acid soil was held in the forms of either exchangeable or water soluble NH4^＋ for a relatively long time and under higher C/N ratio （50：1）, a large amount of the added NH4^＋ was directly immobilized by microorganisms. In the second soil containing appreciable 2：1 type clay minerals a large part of the added NH4^＋ at first quickly entered the interlayer of the minerals under both lower and higher C/N ratios. In second condition, however, owing to microbial assimilation stimulated by glucose the newly fixed NH4^＋ could be completely released in further incubation because of a large concentration gradient between external NH4^＋ and fixed NH4^＋ in the mineral interlayer caused by heterotrophic microorganisms, which imply the fixed NH4^＋ to be available to plants. The results also showed that if a large amount of K＋ with carbon source together was added to soil, the higher K＋ concentration of soil solution could impede the release of fixed NH4^＋, even if there was a lot of carbon source.     

基于傅里叶变换中红外光声光谱的土壤顶空氨浓度的原位测定

Ammonia(NH3) volatilization is one of the important pathways of nitrogen loss in alkaline soil, and the NH3 concentration in soil headspace is directly linked with the NH3 volatilization. Ammonia was characterized by Fourier transform mid-infrared photoacoustic spectroscopy(FTIR-PAS) and two typical absorption bands in the region of 850–1 200 cm-1were observed, which could be used for the prediction of NH3 concentration in the soil headspace. An alkaline soil from North China was involved in the soil incubation, pot and field experiments under three fertilization treatments(control without N input(CK), urea and coated urea). Ammonia concentrations in the soil headspace were determined in each experiment. In the soil incubation experiment, the NH3 emissions were initiated by the N input, reached the highest concentration on day 2, and decreased to the level as measured in CK after 8 d, with significantly higher NH3 emissions in the urea treatment compared to coated urea treatment, especially during the first 4 d. The NH3 concentration in soil headspace of the pot experiment showed the similar dynamics as that in the incubation experiment; however, the NH3 concentration in the soil headspace in the field experiment demonstrated a significantly different emission pattern with those of the incubation and pot experiments, and there was a 4-d delay for the NH3 concentration. Therefore, the NH3 concentration in the incubation and pot experiments could not be directly used to model the real NH3 emission in the field due to the differences in fertilization method and application rate as well as soil temperature and soil disturbance. It was recommended that light irrigation in the second week after fertilization and involvement of controlled release coated urea could be used to significantly decrease N loss from the perspective of NH3 volatilization.     

Salt—Water Dynamics in Soils：Ⅲ.Effect of Crop Planting

Through a simulation test conducted with soil columns (61.8cm in diameter) in field condition,effect of crop planting upon the regulation of salt-water dynamics in soils was studied by monitoring of salt-water dynamics in situ,using soil salinity sensors and tensiometers.The results indicated that the amount of water absorbed by crops from the soil was generally larger than the decrement of water consumption from soil surface evaporation reduced by the crop covering the soil surface and improving the soil structure,therefore,under the conditions of crop growing and non-irrigation,water content in soil profile was less than that without crop growing,and the gradient of negative pressure of soil water in soil profile especially in the root zone was enlarged,thus causing the water flowing from subsoils into root zone and increasing the groundwater moving upwards into soil layer via capillary rise,so that the groundwater evaporation increased.Consequently,under the condition of crop growing,the salt was mainly accumulated towards the root zone rather than to the top soil.the accumulating rate of salt in groundwater via capillary rise of soil water to subsoils was increased thereby.     

土壤盐－水动力学：Ⅳ.水分蒸发与渗漏时土壤剖面离子组成的变化

Through a simulation test carried out with soil columns(61.8 cm in diameter),the changes of ionic compositon in soil profile during the processes of water evaporation and infiltration were studied.Under evaporation conditions,ions moving upward with fresh groundwater were mainly Cl^-1,SO4^2-,Ca^2 ,and Na^ .When the mineralized groundwater took part in the salt accumulation.the ionic composition in soils was close to that in ground water supplemented.Under rainfall infiltration conditions,the salt-leaching role occurred mainly in the top soil.With the decrease of total salt content,NO3^-and Cl^- reduced rapidly,SO4^2- decreased slowly,but HCO3^- had a little change only.Among cations,Na^ and Ca^2 contents lowered at the same speed,and mg^2 decreased slowly.     

增硝营养对不同基因型水稻苗期硝酸还原酶活性及其表达量的影响

利用控制条件下的溶液培养方法,研究了增硝营养(NH4+∶NO3-比例为100∶0和50∶50)对两种不同的基因型水稻南光和云粳苗期生长和硝酸还原酶(NR)活性及基因表达量的影响。结果表明,不同基因型水稻在增NO3-营养下生物量、氮素含量、氮积累量的增幅南光大于云粳。NO3-的存在增强了水稻硝酸还原酶的活力和NR基因OsNia1、OsNia2的表达。不同基因在水稻幼苗中,两个品种OsNia2的相对表达量均高于OsNia1。就品种而言,无论叶片还是根系,增硝后南光OsNia2mRNA表达量都高于云粳;南光叶片OsNia1mRNA表达量也较云粳叶片高。增硝营养提高了水稻NR基因的表达,增加了NR活性,促进了水稻NO3-的同化利用,从而增加了氮素在植株地上部的积累同化。南光和云粳相比,前者对NO3-的响应更为强烈。     

不同氮效率水稻品种增硝营养下根系生长的响应特征

试验采用两室分根盒和溶液培养方法,研究了在增硝营养下不同氮效率水稻品种根系生长的响应特征。结果表明,在本试验条件下,与全铵培养下的根系相比,氮高效水稻品种南光在铵硝混合培养下的根系干重和氮积累量显著增加,增幅达33%和41%;同时其根系表面积、根系体积和侧根数增幅均达到显著水平,但根系长度却无明显增加。氮低效水稻品种Elio在铵硝混合培养下的根系生长差异均不显著。这表明氮高效水稻品种南光的根系生长对增硝营养的响应度强,进而促进了根系对氮素的吸收利用。从本试验的结果可推论,水稻对增硝营养的强响应度可能是水稻氮素高效吸收利用的生理机制之一。     

有机配体、竞争阳离子和pH对土壤中Zn分解的影响

A series of experiments were conducted to examine the interactive effects of an organic ligand, a competing cation, and pH on the dissolution of zinc （Zn） from three California soils, Maymen sandy loam, Merced clay, and Yolo clay loam. The concentrations of soluble Zn of the three soils were low in a background solution of Ca（NO3）2. Citric acid, a common organic ligand found in the rhizosphere, was effective in mobilizing Zn in these soils; its presence enhanced the concentration of Zn in soil solution by citrate forming a complex with Zn. The ability of Zn to form a complex with citric acid in the soil solution was dependent on the concentration of citric acid, pH, and the concentration of the competing cation Ca^2＋. The pH of the soil solution determined the extent of desorption of Zn in solid phase in the presence of citric acid. The amounts of Zn released from the solid phase were proportional to the concentration of citric acid and inversely proportional to the concentration of Ca（NO3）2 background solution, which supplied the competing cation Ca^2＋ for the formation of a complex with citrate. When the soil suspension was spiked with Zn, the adsorption of Zn by the soils was retarded by citric acid via the formation of the soluble Zn-citrate complex. The dissolution of Zn in the presence of citric acid was pH dependent in both adsorption and desorption processes.     

不同氮效率水稻品种苗期吸氮效率差异及其机理研究

以大田筛选得到的不同生物学特性的12个水稻品种为材料,研究了水培条件下这些品种苗期的吸N效率差异,结果表明大田N效率不同的品种在苗期水培条件下吸N效率也不相同,并且大田相同类型的品种在苗期N效率也不完全相同。供试7个大田高产品种中只有桂单4号、云粳38和黔育421这3个水稻品种在水培环境中同样保持较其它品种生物量大,N响应高的特性;另外3个大田高产品种南光、予粳7号和4007在苗期N效率表现很差;红稻Vmax虽然很大,但是生物量很小,所以综合表现一般。3个低产品种Elio、抚宁小红芒和黄金糯中,Elio在苗期N效率很高,另外2个品种N效率不高。研究发现,生物量(尤其是根系的生物量)和对NH4 的亲和力(1/Km)以及Vmax是水稻苗期吸N效率的主要决定因素。典型的苗期N高效品种有桂单4号、黔育421、Elio和云粳38,这些品种苗期N累积量高,N响应值高,原因在于桂单4号、黔育421和Elio在水平增加后Vmax都成倍增加,尤其Elio的Vmax一直都很高,而云粳38则主要是靠较高的生物量来获得高吸N量。典型的低效品种有南光、4007、武运粳7号和予粳7号,这些品种N累积量小,N响应值小,原因在于其中前3个品种在N水平增加后Vmax都降低,Km大幅度增加,而予粳7号虽然Vmax稍有增加,但亲和力则降低最大而成为所有品种中最低的,所以综合结果仍是低效。     

海稻86响应碱胁迫调节氮代谢的生理与分子机制

海稻86是原生长于沿海滩涂的水稻品种,具有强耐碱性。为探究海稻86耐碱胁迫的生理和分子机制,本研究以海稻86和对碱敏感的水稻品种珍汕97为材料,采用pH值9.0的碱处理液处理水稻幼苗,并检测其根和叶中含氮物质含量、氮代谢相关酶活性和基因表达量。结果表明,碱胁迫下,海稻86根和叶中硝态氮和可溶性蛋白含量降幅低于珍汕97,而珍汕97根中氨态氮的积累量显著大于海稻86。碱胁迫下,海稻86根部硝酸还原酶(NR)活性以及根和叶片谷氨酰胺合成酶(GS)活性与非胁迫下对照(CK)相比均无显著变化,叶片NR活性以及根部谷氨酸合成酶(GOGAT)活性降低,叶片GOGAT活性升高;珍汕97根和叶片NR和GS以及根部GOGA活性均显著降低,降幅明显大于海稻86;碱胁迫对海稻86的GDH活性无显著影响,但珍汕97的GDH活性显著升高。此外,碱胁迫下,海稻86和珍汕97的NR以及GDH基因表达量与酶活性变化较一致,NADH-GOGAT基因表达变化与酶活性变化存在差异,OsNADH-GOGAT1和NADH-GOGAT2表达量显著升高,海稻86的NR和GOGAT基因表达量高于珍汕97,GDH基因表达量低于珍汕97。综上表明海稻86具有强耐碱胁迫能力,与其具有较稳定的氮代谢关键酶活性有关。本研究为深入了解水稻耐碱机理和培育耐碱水稻品种提供了重要的理论依据。     

NH4+-N部分代替NO3--N对番茄生育中后期氮代谢相关酶活性的影响

采用砂培实验研究NH4 -N部分代替NO3--N对番茄的影响,结果表明:与全硝处理(100%NO3-)相比较,增铵处理(NH4 ∶NO3-=25%∶75%)下番茄鲜果重显著提高;同时叶片内NO3--N含量随增铵而显著降低,叶片与果实内NH4 -N含量及果实的可溶性蛋白含量随增铵而升高;增铵条件抑制了叶片和果实的硝酸还原酶(NR)活性,提高了叶片和果实的磷酸烯醇式丙酮酸羧化酶(PEPcase)活性及叶片谷氨酰胺合成酶(GS)活性,但对果实的谷氨酰胺合成酶(GS)活性影响不大。上述结果表明,NH4 -N部分代替NO3--N可增加番茄产量,提高集约化基地的生产量。     

不同铵硝比例对水稻铵吸收代谢基因表达的影响

以水稻南光为材料,研究了不同铵硝摩尔比例处理时,水稻NH4^＋吸收代谢基因的表达情况.档结果表明：（1）应用荧光定量PCR方法,可以精确检测水稻氮素吸收代谢基因在不同铵硝处理间的表达量变化;（2）从各基因的表达量上来看,吸收基因中以OsAMT1.1表达量最高,编码GS的基因中以OsGln1.1表达量最高,编码GOGAT的基因中,OsGlu表达量最高;（3）总体来说,不同铵硝处理对NH4^＋吸收代谢基因的表达有显著影响,吸收基因对不同铵硝比例的反应要比代谢基因更敏感;（4）氮吸收基因中OsAMT4.1显著受到NO3的抑制,NH4^＋的诱导.而OsAMT1.1,OsAMT1.2,OsAMT1.3和OsNRT2在铵硝摩尔比例由100：0变为50：50过程中,受到NO3^-的显著抑制,在铵硝摩尔比例由50：50变为0：100过程中OsAMT1.2和OsAMT1.3受到NO3^-的显著诱导,OsAMT1.1和OsNRT2变化不显著;（5）编码GS的基因OsGln1.1表达受NO3诱导,受NH4^＋抑制.OsGln2在铵硝摩尔比例由100：0变为50：50过程中,受到NO3^-增加的诱导,同时,OsGln1.2受到NO3增加的显著抑制作用,铵硝达到50：50以后,NO3^-比例的增加对OsGln1.2和OsGln2的表达没有显著影响;（6）编码GOGAT的基因OsGlt1和OsGlu在不同铵硝摩尔比例中的变化趋势一致：铵硝比例由100：0变为50：50过程中没有显著变化,铵硝比例50：50基础上表达量受到NO3^-比例增加的显著抑制,而OsGlt2的表达受NO3^-的显著抑制,NH;的显著诱导.     

Intraspecific differences in nitrogen assimilating enzymes in spinach under contrasting forms of nitrogen supply 1

Intraspecific differences in the activities of nitrate reductase (NR), glutamine synthetase (GS), NADH dependent glutamate synthase (NADH‐GOGAT), and glutamate dehydrogenase (GDH) under contrasting forms of nitrogen (N) supply were studied in tissues of three spinach (Spinacia oleracea L.) cultivars. The varieties (Viroflay, Butterflay, and Giant) were smooth, curly and semicurly leaved, respectively. The plants were grown in nutrient solutions containing NO₃ as the sole source of N (100:0) and NO₃ plus NH₄ (80:20). Giant, the NH₄ tolerance of which had been evaluated in growth and on the basis of nutrient uptake, had much higher GS and GDH activities in the roots and higher NR and NADH‐GOGAT levels in the leaves of plants grown on NO₃ and NH₄ than that grown on NO₃ alone. On the level of N assimilating enzymes of Butterflay, mixed N nutrition caused an increase of GDH and NADH‐GOGAT in leaves and roots and at the same time a decrease of GS in the roots and NR in the leaves. An inverse relationship between GS and GDH activities was detected in the leaves and foots of Virofiay grown with both N sources. Finally, Viroflay gave the highest levels of GDH irrespective of the NO₃:NH₄ assayed, whereas the leaves of Giant were GDH deficient in comparison with the other cultivars. In addition, the GS activity approached zero in the roots of spinach cultivars characterized by hardly any NH₄ tolerance, whereas in those of Giant it increased remarkably with the supply of NO₃ plus NH₄.     

CO2浓度升高对不同水稻品种幼苗养分吸收和根系形态的影响

本文利用水培试验研究了CO2浓度升高对水稻幼苗生物量、养分含量和根形态的影响,探讨了CO2浓度升高下粤杂889(YZ)和荣优398 (RY)幼苗养分吸收和根系形态的差异性.结果表明,与CO2浓度正常水平(对照)相比,CO2浓度升高显著增加了2个水稻品种幼苗根系、茎叶和总生物量,YZ分别增加58.33％、27.96％、33.16％;RY分别增加45.87％、34.17％、36.07％.同时,CO2浓度升高增加了2个水稻品种的根冠比.CO2浓度升高显著降低了2个水稻品种茎叶中的N、P、K、Ca、Mg和Fe含量,这是“稀释效应”的结果;但YZ幼苗中S含量显著增加,2个品种幼苗Mn含量均显著增加.CO2浓度升高显著增加了2个水稻品种的幼苗根系根毛数、总根长、表面积,降低幼苗粗根比例,增加了细根比例.CO2浓度升高增加了细根在总根长中的比例,有利于水稻对养分的吸收,导致部分营养元素含量增加;但CO2浓度升高条件下水稻生物量的增加使大部分营养元素含量降低.同时,CO2浓度升高对水稻幼苗生物量、养分吸收和根形态的影响存在显著的品种差异.     

不同氮效率水稻生育后期氮代谢酶活性的变化特征

以不同氮效率水稻基因型为供试材料,研究了两个供氮水平下水稻生育后期功能叶和茎秆的氮、可溶性蛋白浓度和氮转运量以及氮代谢关键酶的变化。结果表明:与对照相比,施氮处理能显著增加不同氮效率水稻功能叶和茎秆的氮、可溶性蛋白的浓度和氮转运量。在不同的施氮水平下,水稻从齐穗至成熟顶三叶的氮浓度降低了60%～67%;而茎秆氮在生育后期对籽粒氮的贡献取决于环境供氮水平,与对照相比施氮处理水稻从茎秆转运出的氮大幅提高,在不同的供氮水平下南光的叶片和茎秆氮转运量显著高于Elio。与对照相比,施氮处理增加齐穗期时硝酸还原酶(NR)、谷氨酰胺合成酶(GS)、谷氨酸合成酶(GOGAT)和谷氨酸脱氢酶(GDH)的活性。随生育期的推进,四种氮代谢酶活性随之降低。南光的NR和GS酶活性显著高于Elio,但NR活性受水稻生育期和环境供氮水平的影响较大;南光的GOGAT和GDH的活性显著低于Elio。相关分析表明,NR和GS活性与功能叶和茎秆的氮转运量呈显著正相关。这就意味着水稻生育后期功能叶和茎秆的NR和GS活性高,尤其是GS活性高是筛选水稻氮高效的重要指标。