白洋淀沿湖农田施氮量对冬小麦产量和土壤硝态氮累积的影响

[目的]研究白洋淀沿湖农田施氮量对冬小麦产量及土壤中硝态氮累积的影响.[方法]选择2块具有代表性的农田进行田问小区试验,研究不同施氮量对该地区小麦产量构成因素、氮肥利用率及土壤硝态氮累积量的影响.[结果]适宜施氮量可显著提高小麦的穗粒数、千粒重等产量构成因素及氮肥利用率.土壤硝态氮主要集中在0～30 cm土层,其含量随施氯量的增加而增加.随着小麦生育期的推移,0～90 cm土体中硝态氮累积量呈下降趋势.成熟期,当施氮量分别高于其适宜施氮量时,土体中硝态氮累积量随施氮量增加而显著增加,从而增加了硝态氮下移的风险.[结论]综合考虑产量和环境效益,在该试验条件下,马堡和张六试验点冬小麦的适宜施氮量分别为225、90 kg/hm2.     

施肥对潮土养分非匀衡化的土壤修复研究

[目的]研究施肥对不同处理的土壤修复作用.[方法]利用盆栽试验对长期不合理施肥导致土壤养分失衡及生产力下降的土壤进行施肥修复.[结果]试验结果表明:有机、无机肥配合施用是快速修复土壤养分和提高生产力的最佳方法;NP、NPK是既均衡土壤肥力又提高作物产量的无机肥施用方式;对土壤有效磷、氮极度缺乏的土壤,单施磷肥、氮肥效果极显著,其肥效在小麦上与NPK相同.[结论]长期施化肥的土壤对化肥的依赖性更强,停止施肥,玉米产量下降78.6%,小麦产量下降52.8%;而长期施NK和PK肥的土壤,停止施肥反而产量增加,NK处理玉米产量提高112%,小麦产量增加182%,PK处理中玉米产量增加15.1%,小麦产量增加59%;单施有机肥的当季效果不如化肥,但后效明显好于化肥.     

南平植烟土壤有机质状况及其与土壤养分的关系

[目的]分析南平植烟土壤有机质状况及其与土壤养分的关系.[方法]利用南平植烟土壤普查资料,分析了土壤有机质现状、演变趋势及其与土壤养分的关系:[结果]南平植烟土壤有机质平均含量为(25.97±7.74)g/kg,CV为29.80%,其中15.00～25.00g/kg 的占46.03%,25.00～35.00g/kg的占37.56%.与1994年相比,南平植烟有机质含量呈明显降低趋势,但2008年比2002年又略有增加.土壤有机质与有效S、水溶性Cl含量之间呈显著正相关或负相关,与质地、全N、全N、全K、碱解N、速效K、缓效K、交换性Ca和交换性Mg及有效Fe、Mn、Cu含量之间呈极显著正相关,且与土壤N素的关系最为密切,提高土壤有机质最直接的影响是土壤供氮能力的增强土壤有机质分组后,其养分含量在组间存在显著或极显著差异.[结论)南平烟区应适当增施腐熟有机肥或实施秸秆还田等增加土壤有机质含量,在少数有机质超过45.00 g/kg的烟区,烤烟当季应少施或不施有机肥,或将有机肥在烤烟前茬作物上施用.     

不同类型包膜控释尿素养分释放规律的比较

[目的]为包膜控释尿素在不同类型土壤中的应用提供参考.[方法]以硫包膜与树脂包膜控释尿素为材料,比较研究了它们在壤土与黏土中养分释放的规律.[结果]硫包膜尿素前期(10 d之前)养分释放速率显著高于树脂包膜尿素,而后期(30 d之后)养分释放速率则低于树脂包膜尿素,可见树脂包膜的控释效果较硫包膜好.2种包膜尿素在壤土中的养分释放速率均高于黏土,说明土壤类型对包膜控释肥料的养分释放有显著影响.[结论]树脂包膜尿素适于壤土和黏土类型中施用,硫包膜尿素较适于在黏土类型中施用.     

传统施肥对水稻性状及氮肥利用的影响

[目的]探讨传统施肥模式对水稻性状的影响以及氮肥吸收利用情况.[方法]以扬两优6号为供试品种,设108.0、154.5、201.0kg/hm<'2>3个施氮水平,以不施氮肥为对照,采用传统的施肥技术.[结果]高峰苗、有效穗、株高、穗总粒数、干物质积累量、吸氮量等性状均随着氮肥施用量的增加而增加,结实率和千粒重随着氮肥施用量的增加而降低;产量随施氮量的增加而增加,但达到一定程度后开始下降;氮肥利用率随着施氮量的增加而升高,但普遍较低,不超过23.00%.[结论]传统施肥模式不利于水稻的生长及氮肥的利用,建议实施科学施肥,减少氮肥资源浪费,提高肥料利用率.     

荔浦芋种植过程中土壤养分含量变化及相关性研究

[目的]探索荔浦芋种植过程中土壤养分的含量变化及各养分含量的相互关系,为农业生产提供指导.[方法]在荔浦芋种植过程中的4个时期分别采集土样,并且检测分析.[结果]pH值与土壤有效养分含量密切相关,施加追肥后,土壤pH值明显升高;碱解氮含量在种植前后差异明显;有效磷、有效钾含量随着肥料的施加逐渐增加;微量元素有效态含量在种植过程中也发生了相应的变化.[结论]土壤养分因素之间存在密切联系,各养分含量在种植过程中也发生了相应的变化.适时对土壤养分指标进行检测、分析,才能掌握其变化规律.     

玻璃基质型缓释复合肥养分释放特征

[目的]研究玻璃基质型缓释复合肥料的养分释放率.[方法]以玻璃基质材料和矿质肥料为主要原料, 制备了玻璃基质型缓释复合肥料.在实验室培养条件下,对比研究了玻璃基质型缓释复合肥料的养分释放率.[结果]与普通肥料相比,玻璃基质型缓释复合肥料极显著地降低了氮和钾的释放率(P<0.01).但玻璃基质型缓释复合肥料中的磷释放率很低,与钙镁磷没有显著差别.[结论]玻璃基质型缓释复合肥料对氮、钾具有较好的控释效果.     

模拟酸雨对赣南稀土矿淋滤实验研究

采用模拟土柱淋滤实验研究酸雨条件下浸矿土壤和尾矿土壤中氮化物的迁移.选取有机玻璃管为试验柱,模拟酸雨淋滤液pH为5.4~5.6,测量两类土壤中NH₄+-N、NO₃--N、有效氮含量,实验结果表明:稀土土壤对铵态氮有一定截留作用,铵态氮流失是导致矿区土壤及周边水环境污染的主要原因;铵态氮在两类土壤的含量随着淋洗量增加而逐渐减少;硝态氮在两类土壤的含量随着淋洗量增加呈现先减少至最低再有所回升,且受土壤pH和土壤埋深影响;有效氮在两类土壤中的迁移特征与铵态氮相似. 实验研究为有效控制赣南稀土矿土壤污染和水体污染提供理论基础.      

不同控释氮肥对玉米产量和氮肥利用率的影响

[目的]为控释氮肥在玉米上的广泛应用提供理论依据.[方法]通过田间小区试验,比较了不同控释氮肥对玉米产量和氮肥利用率的影响.[结果]3种控释氮肥中树脂包膜氮肥增产和提高玉米氮肥利用率的效果均最好.相比普通氮肥,不同控释氮肥显著提高了玉米氮肥利用率,增幅达4.99～14.54个百分点.[结论]控释氮肥可以提高玉米氮肥利用率,树脂包膜氮肥在玉米上的应用效果最佳.     

交替A/O工艺处理养猪废水脱氮研究

采用交替A/O工艺处理养猪废水.进行硝化菌与反硝化菌的培养、驯化;交替阶段厌氧和好氧段各自运行的最佳时间的确定;交替A/O工艺对NH3-N、TN、NO3-N的去除情况以及交替A/O工艺对养猪废液脱氮机理的研究.结果表明,A段运行2.5 h,O段运行时间为2 h,交替13.5 h即3个交替过程后,NH3-N的去除率为60.44%,总氮去除率为56.37%,NO3-N去除率22.35%.交替A/O工艺脱氮的去除率突破了传统A/O工艺脱氮的去除率的理论限制,对脱氮机理理论研究有重大的贡献.     

乌鲁木齐市蔬菜基地土壤有效态铅的空间变异特征

以乌鲁木齐市北郊蔬菜基地为典型区,对干旱区绿洲城市郊区土壤有效态铅含量的结构特征进行分析,得出该区有效态铅的空间分布格局并揭示了引起这种分布格局的成因和污染来源,结果表明:乌鲁木齐市北郊蔬菜基地有效态铅属中等变异.半方差函数模型拟合结果表明,有效态铅含量可以用指数函数拟合,且在一定范围内存在空间相关性.采用Kriging最优内插法得到了有效态铅含量的空间分布格局,表明土壤有效态铅含量与工业活动、污水灌溉和大气降尘密切相关.     

不同类型土壤有机碳含量比较研究

[目的]研究不同类型土壤有机碳含量及其影响因素.[方法]以武夷山不同类型土壤为研究对象,进行土壤有机碳含量及基本理化性质的测定,分析不同类型土壤有机碳含量与土壤基本理化性质、海拔高度、年均气温等因素之间的关系.[鲒果]武夷山不同类型土壤的有机碳含量在14.91～112.34 g/kg;土壤有机碳与速效养分(速效氮、速效磷和速效钾)和全氮呈正相关,与海拔高度和年均气温成显著指数关系.[结论]武夷山不同类型土壤有机碳含量受土壤理化性质、海拔高度及年均气温影响显著.     

Effective Soil Density for Propagation of Small Strain Shear Waves in Saturated Soil

This technical note defines an “effective soil density” that controls the velocity of small strain shear waves in saturated soil. Biot theory indicates that the ratio of effective density to saturated density will generally range from 0.75 to 1.0 and is a function of specific gravity of solids, porosity, hydraulic conductivity, and shear wave frequency. For many geotechnical applications, effective density will be equal to saturated density for low hydraulic conductivity soils (clays and silts) and may be less than saturated density for high hydraulic conductivity soils (clean sands and gravels). The findings are relevant to applications involving the propagation of small strain shear waves through saturated soil, and in particular for laboratory and field tests in which shear modulus is back-calculated from measured shear-wave velocity.     

外源镧在红壤中的有效性及其对土壤酸度的影响

通过培养试验及盆栽试验研究了外源镧在红壤中的有效性及其对土壤酸度的影响。结果表明,土壤有效态镧随外源镧的增加而增加,两者呈显著的正相关;外源镧在土壤中具有较高的有效性,随着时间的延长有效性逐渐降低;土壤pH随外源镧的增加不断降低,pH和外源镧及有效态镧均呈显著的负相关;过量的镧对土壤生态环境将产生破坏作用。     

土壤电动修复中匀强电场对土壤细菌群落的影响

对土壤电动修复过程中匀强电场对土壤细菌群落的影响进行研究土壤细菌计数及PCR-DGGE研究结果显示,在匀强电场中,电场强度与土壤细菌的数量和多样性存在着密切的相关性在电场强度为3.0 V/cm时,电场对土壤细菌的刺激与抑制作用基本平衡.较低的电场强度刺激土壤细菌生长繁殖,高电场强度显著抑制甚至致死土壤细菌在匀强电场中,中间土壤细菌群落受到的影响较小,电极附近土壤细菌群落受到的影响较大.电场阳极对土壤细菌的数量和多样性产生较大影响,而电场阴极对土壤细菌群落结构的影响较大.     

Nitric Oxide Emission and Soil Microbial Activities in Toluene Contaminated Soil

The purpose of this research is to consider a novel concept for measuring and monitoring (M&M) the presence and levels of contaminants in soil. Current M&M techniques include direct sensing for the target contaminant and the surrogate indicators of respired O2 and CO2. The method suggested here is based on nitric oxide (NO). It is an alternative M&M method that could become quicker, easier, more reliable, and less expensive than the other M&M methods being used currently. NO emission from toluene contaminated soil and soil microbial activity were investigated to understand the NO-toluene-soil microbial relationships using fluorescent in situ hybridization molecular technique combined by enzymatic method. The relationships have been analyzed by the comparison of experimental measurements coming from analysis of variance statistical analysis, referring to toluene concentrations. Relationships between NO emissions and the microbial activity were significantly correlated (P<0.01) with the level of toluene concentration and duration of toluene contamination. Thus, NO emissions are suggested as a useful indicator of microbial activity in toluene contaminated soils.     

Rate of Capillary Rise in Soil

A rigorous closed-form analytical solution is developed for analyzing the rate of capillary rise in soils. The new solution can be reduced to Terzaghi’s classical solution if the nonlinearity in the hydraulic conductivity with changing soil suction is ignored. Results obtained using the new solution are compared with Terzaghi’s classical solution and a series of previously documented experimental data from open-tube capillary rise tests. The new solution is a significant improvement over the previous solution, thus providing more realistic and practical predictions for the rate of capillary rise in unsaturated soils.     

含铅土壤中铅的浸出行为

采用BCR连续浸提法分析含铅土壤中铅的存在形态,通过静态溶浸与动态淋滤试验研究了土壤中铅的浸出行为,结合浸出毒性分析,探讨了添加活性炭对土壤中铅的稳定性影响。结果表明,供试土壤中可交换态铅可转化为可还原态和可氧化态形式存在,活性炭对不稳定态的铅有较强吸附作用。添加活性炭对降低土壤中铅的浸出有一定效果,并且与活性炭性质和淋溶体系pH有关,醋酸体系浸提剂比硫酸体系对铅的浸出浓度影响更大。     

Interaction of Soil Air Permeability and Soil Vapor Extraction

A new theoretical model to analyze the measurements obtained from a typical soil column venting experiment is proposed. The principles of mass transfer, Darcy's law, and air compressibility in the form of pressure-volume relationships were coupled to calculate the contaminant concentration in the gas phase (air), and the rate of contaminant removal. The proposed model relates soil air permeability with the contaminant removal and is capable of calculating the variation of soil air permeability with time during the venting process. The contaminated sand sample was idealized as a system of straight capillary tubes in the direction of flow, lined by the liquid contaminant. A closed-form solution for radial diffusion of the contaminants in a cylinder, coupled with axial advection of air, was used to model contaminant removal. The results from the mass transfer model were then used to trace the change of soil air permeability with time. The model also uses, as an alternative approach, a modified form of Darcy's law for compressible flow.     

Pool Sizes and Turnover of Soil Organic Carbon of Farmland Soil in Karst Area of Guilin

The three-pool and first-order model separates the mineralizable orgaruc carbon into active, slow, and passive carbon pools. This paper used the model and decomposition curves of the soil orgaruc carbon to fit the active pool and its decomposition rate, slow pool and its decomposition rate. The results showed that the size of the active pool from different profiles accounted for 2.09%-3.08% of the total soil organic carbon and the mean residue time was 3.57-17.21 days. And the size of the slow pool accounted for 3.19%-43.55% and the mean residue time was 1.12-4.94 years. Acid hydrolysis (6M HC1) was used to fractionate the passive organic carbon, which accounted for 50.83%-94.44% of the total soil organic carbon.