紫色土坡地土壤性质对耕作侵蚀的影响

[目的]揭示土壤性质对耕作侵蚀土壤的敏感性,为紫色土区域采取适宜的耕作措施提供依据。[方法]利用磁性示踪技术定量旋耕机上下耕作和等高耕作的土壤耕作位移和土壤位移量,选取土壤容重、土壤含水量、土壤有机质、土壤全氮、土壤有效磷、土壤抗剪强度和土壤紧实度等土壤理化性质和力学性质指标,研究土壤性质对旋耕机上下耕作和等高耕作的耕作侵蚀的影响特征。[结果]旋耕机上下耕作和等高耕作的土壤净位移和净位移量不仅受坡度影响,也受土壤性质的影响。土壤力学性质和土壤物理性质对旋耕机耕作侵蚀有显著影响,对于上下耕作的土壤抗剪强度、土壤紧实度和土壤容重与土壤净位移量呈显著正相关。对于等高耕作措施的土壤抗剪强度、土壤紧实度、土壤容重和土壤含水量与土壤净位移量呈显著正相关,其他指标关系不显著。[结论]土壤抗剪强度、土壤紧实度和土壤容重可以作为评价耕作侵蚀的土壤可蚀性指标。     

土壤动物与土壤健康

土壤动物与土壤健康息息相关,土壤动物多样性和功能能够灵敏反映人类活动和气候变化引起的土壤扰动。同时,土壤动物还通过与生物和非生物组分间的相互作用对地上生态系统产生反馈作用。当前土壤动物在土壤健康评价体系中的应用相对较少,主要集中在土壤线虫、节肢动物和蚯蚓等类群,仍缺乏基于土壤动物的系统性评价指标。因此,本文围绕土壤动物在指示土壤健康方面的潜力,系统总结了现有基于土壤动物的土壤健康评价指标,强调未来应建立和完善土壤动物基因组信息数据库,挖掘土壤动物的功能性状,加强土壤食物网结构和生态功能的研究,建立集成土壤动物物种多样性、功能性状和土壤食物网的指标体系,从而促进土壤健康和生态系统的可持续发展。     

磷肥和有机肥对不同磷水平土壤磷吸附-解吸的影响

采用培养试验结合Langmuir吸附等温方程进行拟合求出吸附、解吸的相关参数的方法,研究了磷肥和有机肥对不同磷水平土壤磷吸附和解吸特性的影响。结果表明,随土壤磷水平和磷肥和有机肥用量的增加,土壤最大吸磷量、土壤磷最大缓冲能力显著降低;土壤易解吸磷和土壤磷的解吸率显著增加。土壤易解吸磷和土壤磷的解吸率与土壤Olsen-P呈显著正相关;土壤最大吸磷量、土壤磷最大缓冲容量与土壤Olsen-P呈显著负相关。单位量磷肥所增加的土壤易解吸磷随着磷肥用量和土壤磷水平的增加而增大;土壤磷水平和磷用量是影响土壤磷最大吸磷量和土壤磷最大缓冲能力的重要因素。     

珠穆朗玛峰北坡土壤过氧化氢酶与蔗糖酶活性研究

土壤酶主要源于土壤微生物代谢过程,以及土壤动物、植物根系分泌及残体分解[1,2],土壤酶活性反映土壤生物活性和土壤生化反应强度[3]。土壤酶活性与土壤物理特征(土壤水分、土壤温度、土壤空气、土壤团聚体)、有机质、pH、土壤微生物及土壤类型等关系密切[4]。环境因子如温度和湿度的变化、酸雨和臭氧等污染对土壤酶活性的影响也很大[5,6],因而土壤酶活性也可作为监测环境变化和污染对土壤质量影响的生物活性指标。此外,由于土壤酶活性与土壤碳、氮循环密切相关[7],因此土壤酶活性的研究常常还与全球气候变化相联系。目前土壤酶研究多集中…     

三峡库区植物篱系统土壤颗粒分形特征及其与土壤理化性质的关系

在对长江三峡库区坡耕地植物篱系统调查样地土壤样品颗粒分析的基础上,对植物篱系统内土壤颗粒分布及土壤分形维数与土壤物理性质和土壤养分含量的关系进行了研究,结果表明:（1）乔木类、草本类和灌木类植物篱带间坡耕地土壤砂粒含量比其对应的植物篱带内土壤沙砾平均含量分别高10.4%,13.7%和9.2%;而黏粒含量在植物篱带内富集,其平均含量比植物篱带间坡耕地土壤黏粒含量分别高14.3%,19.5%和10.7%;（2）土壤分形维数与土壤黏粒和土壤粉粒含量具有显著（P < 0.01）的正相关关系,而与土壤砂粒含量显著负相关。（3）土壤分形维数与土壤孔隙度、含水量和土壤饱和导水率极显著正相关,而土壤容重与分形维数呈显著负相关关系。土壤分形维数与土壤有机质、土壤全氮、土壤有效氮、土壤全钾、土壤有效钾、土壤全磷含量和阳离子交换量显著相关,而土壤有效磷含量和土壤分形维数相关性不显著。     

土壤质量生物学指标研究进展

本文对近年土壤微生物、土壤酶活性和土壤动物等土壤质量生物学指标研究成果进行了综合评述。土壤微生物是土壤有机组分和生态系统中最活跃的部分,被认为是最敏感的土壤质量生物学指标:微生物生物量代表参与调控土壤中能量和养分循环及有机物质转化所对应微生物的数量,但须结合多样性研究以弥补其无法反映土壤微生物组成和区系变化的缺陷;微生物群落组成和多样性动态反映土壤中生物类群的多变性和土壤质量在微生物数量和功能上的差异;土壤微生物活性体现在土壤微生物商、微生物呼吸和代谢商等方面,应考虑生物量大小与微生物种群活性间的相关关系以反映微生物种群内的差异。土壤酶活性具有极高时效性,在较短时间内就能反映出土壤质量的变化。土壤动物通常以种类的组成和数量,土壤动物区系的相对丰度、多样性或活性作为评价土壤生物质量的敏感指标。与土壤理化指标相比,土壤生物学指标更能对土壤质量的变化做出灵敏迅速的响应,因而被广泛地用于评价土壤质量。     

霍林河下游典型洪泛区湿地土壤pH值和土壤含水量分布特征

以霍林河下游洪泛区湿地为研究区,采用网格采样法研究了土壤pH值和土壤含水量的时空变化及其相互关系。结果显示,研究区湿地土壤含水量和pH值存在明显的季节性差异,7月份土壤含水量高于9月份土壤,但7月份土壤pH平均值则低于9月份,9月份湿地土壤,尤其是亚表层发生明显碱化。湿地土壤含水量和pH值均呈现出条带状和斑块状的空间分布格局,尤其在9月份的空间变异性较高,且土壤pH值与土壤含水量间存在较显著的负相关关系,即含水量高的区域对应土壤pH值较低。土壤含水量和pH值的回归分析表明当土壤pH值>8.8时,非线性回归更适宜描述研究区土壤含水量和土壤pH值的显著负相关关系。     

土壤水力侵蚀对土壤质量理化指标影响的研究综述

土壤水力侵蚀对土壤理化性质的影响对控制土壤侵蚀、采取合理水土保持措施有着重要意义。该研究从土壤质量理化指标(土壤容重、土壤团聚体、土壤颗粒组成、土壤有机碳、土壤养分、阳离子交换量、土壤酸碱度)7个方面总结了土壤水力侵蚀对土壤质量影响的研究成果,系统地研究了土壤水力侵蚀影响土壤质量理化指标的过程和机理,筛选出反映土壤水力侵蚀的土壤理化基础指标因子,并分析了这些指标因子对土壤水力侵蚀的响应状况,总结了目前土壤水力侵蚀对土壤理化性质研究中存在的问题,对未来重点研究方向进行了展望,以期为深入研究水力侵蚀与土壤理化指标间的交互作用和反馈机制提供参考,为土壤质量评价研究提供基础理论依据和研究思路。     

pH和磷对铅胁迫下芥菜生长和土壤酶活性的影响

采用盆栽试验研究不同pH和磷酸盐浓度对铅污染土壤种植的芥菜生物量和铅吸收的影响,及铅浓度与土壤酶活性的关系.结果表明,芥菜地下部分铅含量明显高于芥菜地上部分.土壤酸化有可能导致土壤中铅的溶出释放,在试验中,土壤pH为5.0时,土壤中铅的释放最多,芥菜生长和土壤酶活性受到的影响最大.土壤中铅与磷酸结合成难溶性的磷酸铅,当土壤中施加的磷浓度为300mg/kg时,土壤中铅的释放量最少,芥菜生长和土壤酶活性受到的影响最小;土壤中铅的释放溶出与土壤酶活性相关性较大,同时二者易受土壤pH和磷含量的影响,因此把土壤中铅的释放溶出与土壤酶活性结合起来作为判断土壤铅污染程度指标更合适.     

中国主要类型土壤若干重金属临界含量和环境容量区域分异的影响

本文通过八年研究结果，分析了土壤区域，地带性土壤类型分布，土壤ｐＨ，碳酸盐，有机质等因素对Ｃｄ，Ｃｕ，Ｐｂ，Ａｓ四种元素土壤临界含量和环境容量区域分异的影响，其中以土壤ｐＨ和土壤类型分布是主要影响因素。Ｃｄ和Ｃｕ的土壤临界含量，环境容量和土壤ｐＨ间呈负相关性，并随土壤类型由北到南的分布而减小。土壤Ａｓ的临界含量和环境容量随土壤ｐＨ增大和土壤类别由南到北的分布而增大。但它们之间无相关性。     

直链烷基苯磺酸盐(LAS)在土壤-植物系统中的生态学行为研究

More and more linear alkylbenzene sulfonate (LAS) has contaminated the water and soil via pollution discharge, making it important to identify the ecological behavior and toxicity of LAS so as to carry out measures that will reduce its negative effects on the ecosystem. The ecological behavior of LAS, including degradation, migration, and plant uptake, in both soil-paddy rice and soil-soybean systems was studied. Reduction of LAS in pot and field plots followed the first order reaction kinetics with degradation half-lives of 35-50 days with LAS decreasing to very low concentrations after a season of crop growth. Strong migration ability for LAS was found and the breakthrough time in a 1.5 m soil monolith was significantly shortened to 23 days by preferential flow. Leachate volumes of soil-paddy and soil-soybean systems at preferential breakthrough were much different, while the leachate volumes at equilibrium governed by soil adsorption/desorption processes were very similar. Significant uptake of LAS in both paddy rice and soybeans was observed in pot and field experiments (P < 0.05). In aquatic culture, 20 ug mL^-1 and above of LAS significantly inhibited the growth of paddy seedlings (P < 0.05). The critical concentration for LAS in soil inhibiting the growth and yield of paddy was 160 ug g^-1; when higher, there was a strong negative influence, with decreases in height, spike length, and production; when lower than 80 ug g^-1, paddy growth was stimulated. There was little effect of LAS on soybeans.     

Adsorption and desorption of arsenate in Louisiana rice soils

Adsorption and desorption of arsenic (As) in the soil are dominant parameters that affect the mobility and bioavailability of arsenic. Batch arsenate adsorption and desorption experiments were conducted using soils collected from three Louisiana, USA, aquaculture ponds representing different crayfish farming and rice cultural practices. Arsenate adsorption behavior in the soils was investigated using Freundlich and Langmuir sorption equations. Results demonstrated that the Langmuir isotherm model was the best fit based on statistical correlation with soil properties governing adsorption, for the entire range of arsenate concentrations for all soils. Adsorption of As(V) was governed by soil physicochemical properties especially Fe and Al oxides, clay and organic matter. Desorption of As(V) was initially fast, but with increasing incubation times desorption occurred progressively slower. Chemical fractionation of arsenic in the soils showed that the most mobile fraction represented 4.74–5.18% of the total arsenic. A part of this mobile fraction could potentially be taken up by rice and enter the food chain, but would require additional research to quantify.     

青海湖流域土壤大孔隙特征与理化性质的相关性研究

土壤大孔隙是土壤水分、空气和化学物质运移优先流的主要途径。本文以青海湖流域土壤为研究对象,在青海湖沙柳河流域取原状土柱,利用CT扫描与Fiji软件相结合的方法,实现了土壤大孔隙结构的三维可视化,以及断层横截面土壤大孔隙度、大孔隙数量和大孔隙等效直径等的量化;并探讨了样地土壤大孔隙特征与理化性质的相关性。结果表明:青海湖流域土壤大孔隙主要分布在土壤表层0~100 mm,100 mm以下大孔隙较少;土壤全磷含量分别与土壤大孔隙数量、大孔隙等效直径有显著相关性;土壤全氮、有机质含量分别与土壤大孔隙平均等效直径有显著相关性;土壤体积质量与大孔隙度、大孔隙平均等效直径等有显著相关性;土壤中0.002≤Ф0.02 mm的颗粒含量与大孔隙的分布特征相关性较大。     

表面活性剂LAS对土壤Cd形态及Cd在黄豆植株中分配的影响

A pot experiment was conducted to study the effect of an anionic surfactant linear alkylbenzene sulfonate （LAS） application on cadmium （Cd） fractions in soils and Cd distribution in different tissues of soybean （Glycine max） plants as well as soil pH. Soil samples were treated with three levels of Cd （0, 5, and 10 mg kg^-1） and five levels of LAS （0, 5, 15, 50, and 100 mg L^-1）. Results indicated that compared to the control soils （no Cd and no LAS treatment）, soil pH increased and available Cd decreased in the soil treated with external Cd and watered with LAS solutions. Meanwhile, soil exchangeable Cd and Cd bound to carbonates decreased; Cd bound to amorphous iron and manganese oxides and Cd bound to organic matter increased. In addition, LAS application could reduce enrichment of Cd in soybean plants, resulting in decreased Cd in the soybean plants. Thus, suitable LAS application could decrease bioavailability and mobility of soil Cd.     

Transport of microorganisms through soil

Microorganisms migrating into and through soil from sources on the land surface may cause a serious threat to both ground and surface waters. It has been estimated that microorganisms can migrate significant distances in the field. Results from various studies suggested that preferential flow through macropores, worm holes, cracks, and fractures is the main reason for such observations. However, a quantitative representation of this phenomenon has not been provided. Microorganisms migrate through soil by advection and dispersion, while being subjected to effects of filtration, adsorption, desorption, growth, decay, sedimentation and chemotaxis. Both laboratory and field investigations have contributed important information on bacterial movement in soils. Qualitative comparisons are generally transferable from laboratory to field situations. Quantitative agreement is much more difficult to establish. Available mathematical modelling of microbial transport is limited in practical application because of the simplifying assumptions used in its development.     

Simulation of calcium leaching and desorption in an acid forest soil

The aim of the study was to evaluate effects of mobile and immobile water and diffusion‐limited transport on the binding and release of ions in soils. The desorption and leaching of calcium in a humic layer of a densely rooted acid forest soil under a beech stand was studied in laboratory experiments by leaching soil columns with a desorption solution and recycling the leachate through the columns. Radioactive tracers were added and monitored in the leachate to evaluate desorption and leaching characteristics of the soil. Parallel experiments were conducted with chloride and calcium to determine transport and desorption parameters independently. The experimental data were then analysed with a transport model, taking into account effects of mobile and immobile soil water fractions, and in the case of calcium assuming an equilibrium Langmuir adsorption isotherm. The transport was highly dependent on the mobility of the soil water, and in particular the fraction of the soil water to which the chemical was confined as a result of ionic properties. For chloride an excluded soil water phase had to be taken into account to explain the experimental findings. Immobile or mobile water and solute transfer and transport properties were not sufficient to explain non‐equilibrium effects in the adsorption reactions. Desorption curves agreed with results from batch experiments, provided the leaching experiments were done in such a way that equilibration between the soil solution and the solid matrix adsorption sites was reached, otherwise desorption was delayed and the calculated isotherms do not represent actual equilibrium adsorption–desorption conditions.     

不同土地利用方式土壤对铜、镉离子的吸附解吸特征

采用一次平衡法对Cu²⁺、Cd²⁺在城市及城郊农田、林地、草地3种土地利用方式土壤中的吸附解吸过程进行比较研究, 结果表明: Cu²⁺、Cd²⁺在3种土地利用方式土壤中的吸附量均随平衡液浓度的增加而增大, Cu²⁺、Cd²⁺在农田土壤上的吸附量均高于林地和草地土壤。分别用Langmuir和Freunlich两种等温吸附方程对吸附过程进行拟合, 3种土壤对Cu²⁺的吸附过程运用Langmuir方程拟合效果好, 而对Cd²⁺的吸附过程运用Freunlich方程拟合效果更好。Cu²⁺在3种土壤的解吸量大小顺序为农田>林地>草地, Cd²⁺在3种土壤的解吸量大小顺序为农田>草地>林地。两种离子在3种土壤中的动态吸附是个快速反应的过程, 随时间延长, 吸附反应趋于平衡。运用双常数函数方程和Elovich方程能较好地拟合重金属在土壤上的吸附动力学过程。Cu²⁺、Cd²⁺的吸附与土壤黏粒含量、有机质含量、CEC和pH均有关。     

Soybean root morphology in soils with and without tillage pans in the lower Mississippi river valley 1

During 1980, an extremely dry growing season, soybean (Glycine max L. Merrill) root morphologies were characterized at the R2 growth stage in Steele, Sharkey, Rilla, Calloway, and Stuttgart soils with a tillage pan and with a disrupted tillage pan. Results showed that the presence or absence of tillage pans resulted in dramatic changes in the soybean root morphology. Without pans, classical taproot systems tended to develop. With pans, soybean root systems tended to follow old root channels and fractures through the pan. Below the pan, soil structure manifested strong influences on root morphology. On all soils except the Steele (loamy sand), roots penetrated the tillage pan in numbers comparable to those penetrating the soil horizons with the pan disrupted. Although soil impedance to root penetration increases with drying and the 1980 growing season was exceptionally dry, mechanical impedance to soybean root penetration of tillage pans on silt loam and clay soils did not appear to be a problem. However, on the loamy sand soil mechanical impedance inhibited soybean root penetration and appeared to be a major problem.     

The fate of cadmium in field soils of the Danubian lowland

The susceptibility of soils to deep penetration of cadmium was assessed by measuring cadmium adsorption on soil particles <0.01 mm, easily mobile in soil macropores, and bypassing ratio. The latter is defined as a ratio of the rate of macropore flow to the rate of total (macropore and matrix) flow. Measurements were made on soils from the Danubian lowland, which is a large (1260 km²) agriculturally managed area situated in the south-west of Slovakia, with a shallow (0.5–3.8 m deep) underlying aquifer containing about 10 km³ of freshwater. In this study, the susceptibility of soils to deep penetration of cadmium was assessed on light, loamy-sand soil in Kalinkovo, medium heavy, loamy soil in Macov, and heavy, clay soil in Jurova. It was found that when the interaction between soil and cadmium lasted 1 min, more than 35, 32, and 48% of cadmium was adsorbed on the particles <0.01 mm in soils from Kalinkovo, Macov, and Jurova, respectively. In the case of ponding infiltration, more than 50% of water can flow via topsoil macropores in Kalinkovo, about 70% in Macov, and 96% in Jurova. This value of bypassing ratio can be met during an irrigation/rain with higher intensity then the infiltration rate into the soil matrix of studied soils. As the rains resulting in the macropore flow can occur 24 times on average in south-western Slovakia during the vegetation season, the probability of deep penetration of cadmium is very high, mainly during an initial stage of rainfall. For this reason, some mitigative agricultural practices (e.g. subsurface fertilizer banding or shallow ploughing) should be used in this region to prevent soils from the deep penetration of cadmium.     

紫色土坡耕地土壤大孔隙流的定量评价

为阐明大孔隙丰富且孔径呈两极分化的紫色土坡耕地土壤大孔隙流的运移规律,通过室内土柱试验获取耕作层0~20 cm、非耕作层20~40 cm原状土柱和填装土柱的穿透曲线,分析饱和条件下土壤大孔隙流发生规律,并采用解析法CXTFIT软件拟合了水分优先运移参数,PFSP指标(大孔隙流引起的穿透曲线延展量与水动力弥散作用及两区作用引起的延展量的比值)定量评价土壤大孔隙流的贡献率。研究结果表明:1)以填装土柱水流为平衡基质流计算,耕作层0~20 cm原状土柱中大孔隙流的导水贡献率为66.2%~68.5%,而Br-累积淋出量占总淋出量的62.3%~66.1%。对于非耕作层20~40 cm,土壤大孔隙流导水贡献率为0.2%~1.7%,而Br-随大孔隙流运移的比例却达14.5%~20.5%。说明耕作层土壤中大孔隙流现象远比在非耕作层土壤中更为显著;2)PFSP值结果表明大孔隙流作用对穿透曲线延展量的贡献率最大,两区交换运移作用次之,水动力弥散作用的最小。即PFSP值越大,大孔隙流对总水流通量的贡献率越大。