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对叶尔羌河流域棉田土壤有机碳、全氮垂直分布状况进行了研究.结果表明:(1)剖面分布上不同地貌棉田土壤中有机碳、全氮含量随土壤深度呈下降趋势,冲积扇、扇缘、冲积平原不同土层有机碳、全氮含量变化规律为0~20 cm20~40 cm40~60 cm;(2)叶尔羌河流域棉田土壤中C/N为4.39~16.12,C/N在0~20 cm土层最高,在40~60 cm的土层最低,冲积扇、冲积平原不同土层C/N随土壤深度的增加而降低,而在扇缘不同土层C/N随土壤深度的增加而上升. 相似文献
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以空间代替时间方法研究了黔西北喀斯特地区植被自然恢复演替过程中草本群落阶段、藤刺灌丛阶段、灌乔林阶段、次生乔林阶段和顶级群落阶段的土壤环境,结果表明:随着演替的进行,0～20 cm土层土壤容重逐渐下降,到顶级群落阶段仅为0.9492 g/cm3;20～40 cm及40～100 cm土层土壤容重逐渐升高,但0～100cm土层平均容重逐渐降低; 0～20cm土层含水量逐渐升高,顶级群落阶段明显高于其它阶段;20～40锄及40～100cm土层含水量随植被恢复演替呈总体下降趋势. 相似文献
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土壤团聚体是土壤结构的基本单元,对改善土壤质量和提升养分含量具有重要作用.为研究不同改造模式下川中丘陵区柏木人工林土壤团聚体特征,以绵阳市盐亭县林山乡柏木人工林为研究对象,基于干筛法和湿筛法比较分析疏伐改造(ET)、林窗改造(FG)、林带改造(SF)和柏木纯林(PC)4种模式0～40 cm土层深度下土壤团聚体粒径分布特征和稳定性指标.结果表明：(1)在干筛处理下,4种模式的柏木人工林土壤机械性团聚体以>2 mm为主,含量为48.07%～74.74%,而0～20 cm土层表现为疏伐改造显著高于林带改造,20～40 cm土层表现为柏木纯林显著高于林窗改造和林带改造.(2)在湿筛处理下,0～20 cm土层>2 mm粒径土壤水稳性团聚体表现为林带改造显著高于柏木纯林与林窗改造,0.053～0.25 mm粒径团聚体表现为林窗改造显著高于疏伐改造与林带改造.(3)平均重量直径(MWD)和几何平均直径(GMD)0.56～1.77,土壤水稳性团聚体MWD和GMD在0～20 cm土层表现为疏伐改造显著高于林窗改造.这表明,改造模式能够显著影响柏木人工林土壤团聚体粒径分布和稳定性特征,本研究为... 相似文献
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《赤峰学院学报(自然科学版)》2020,(2)
以沙地云杉林幼龄林、中龄林、近熟林三种林型土壤为研究对象,采用对比分析的方法,研究了3种林型不同土层0-10cm、10-20cm、20-30cm、30-40cm、40-50cm硝态氮、树脂磷总磷及全钾含量季节性动态特征.为沙地云杉土壤养分季节动态变化提供一定的理论依据. 相似文献
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土壤耕作方式对小麦产量及水分利用的影响 总被引：2，自引：0，他引：2
采用大田对比方法研究了轻壤土质夏闲期土壤耕作方式对小麦产量及水分利用效率的影响,结果表明：在冬前气温偏高、小麦生长中后期较为干旱的年型条件下,不同土壤耕作方式的小麦产量以全耕层深松〉隔行深松〉浅旋灭茬〉免耕〉传统耕作．水分利用效率则以全耕层深松〉隔行深松〉传统耕作〉浅旋灭茬〉免耕;明确了不同土壤耕作方式0～100cm、100～200cm土层在不同生育期的贮水量及不同生育时段的耗水量。 相似文献
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《实验室研究与探索》2016,(9)
选取福州茉莉种植土壤,对常规与有机种植模式下的0~50 cm土层土壤团聚体组成与分布、平均质量直径D_(MW)、几何平均直径D_(GM)、分形维数(D)进行了测定与分析。结果表明:1常规茉莉种植土壤在0~50 cm土层以微团聚体(0.25mm)含量最高,67.63%,而1 mm粒级团聚体含量最低,4.13%;有机茉莉种植土壤在0~20 cm土层以大团聚体(R0.25)含量居多,59.30%,在20~50 cm土层以微团聚体(0.25 mm)所占比重大,53.36%;2有机种植在0~50 cm土层(R0.25)含量增加,分别提高了84.27%、126.85%、235.38%;3与常规种植相比,有机茉莉种植土壤团聚体D_(MW)和D_(GM)在0~50 cm土层均有所提高,常规和有机茉莉种植土壤团聚体D分别为2.84~2.92和2.53~2.85,有机茉莉种植土壤团聚体D相对较低,表明有机种植提高了土壤团聚体的稳定性。 相似文献
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烤烟Ne82及K326苗期(出苗、十字、生根、成苗)以土壤相对持水量分别保持90%、70～80%、60%、60%有利于种子萌发,幼苗成活和壮苗的培育,土壤水分过多或过少均影响种子萌发及幼苗成活和烟苗地上、地下部的协调生长,成苗期烟苗的净光合速率(Pn)以土壤相对持水量为60%时最高,水分过多、过少均使Pn下降,光合产物的积累减少. 相似文献
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为探索间作模式对农田土壤及作物行间大气温湿度的影响,研究了马铃薯-玉米间作和马铃薯单作两种模式下,马铃薯行间土壤和空气温湿度的变化情况.结果表明:0—20 cm土层的平均土壤水分间作较单作大20%以上,而且间作0—60 cm土层的温度标准偏差不超过2.5℃,而单作土壤温度随深度的增加表现为较大的突变.马铃薯单作模式下大气温度高于马铃薯和玉米间作模式,特别是在降雨较少时影响更为显著,如在8月17日,单作模式大气温度较间作平均高6.4%,在9月3日田间湿度间作比单作高12.27%,说明在降雨量不足时,间作种植模式能提高田间湿度.间作模式可以在降温时达到土壤增温、保温与双向动态调控的效果,对温度的变化具有一定的缓冲效应;间作种植模式还能有效减少土壤水分蒸发消耗量,且更好地吸收和利用深层土壤水分,从而提高土壤水分利用效率. 相似文献
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以新疆博斯腾湖西岸湖滨带为研究区,利用相关分析和主成分分析法对土壤离子盐分特征进行研究,结果表明:(1)010 cm土层中平均盐分含量为5.413 g·kg-1,占整个土层盐分含量的42.5%,土壤盐分表聚现象明显;(2)垂直方向上土壤含盐量在010 cm土层中平均盐分含量为5.413 g·kg-1,占整个土层盐分含量的42.5%,土壤盐分表聚现象明显;(2)垂直方向上土壤含盐量在010 cm土层变异系数为1.012,属于强变异程度,其它深度土壤盐分含量均属于中等变异;(3)通过相关性分析,该区域土壤盐分组成以硫酸盐和氯化物为主.在010 cm土层变异系数为1.012,属于强变异程度,其它深度土壤盐分含量均属于中等变异;(3)通过相关性分析,该区域土壤盐分组成以硫酸盐和氯化物为主.在010 cm土层中SO2-4和Na++K+的相关系数为0.955;在1010 cm土层中SO2-4和Na++K+的相关系数为0.955;在1050 cm土层中CL-与Na++K+相关系数为0.970;(4)通过对影响土壤盐渍化主导因子的主成分分析得出,土壤含盐量、Na++K+、SO2-4及CL-是表征博斯腾湖西岸湖滨带土壤盐渍化主要特征因子. 相似文献
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盐渍土水分下渗能力及水盐动态运移试验 总被引：1，自引：0，他引：1
为探究盐渍化土壤水分下渗规律、水分下渗能力及水盐动态运移过程,设计了土壤剖面分层定水头供水及土壤剖面变水头供水下渗实验。测定不同层位土壤水分下渗率、含水率、孔隙水溶液电导率及土壤体电导率等参数,进行入渗条件下水盐动态运移规律分析。试验结果表明:盐渍化土水分下渗规律可由积水入渗Kostiakov模型进行刻画;浅层0~40 cm土壤相对于深层40~60 cm土壤具有较强的拦截和贮存入渗水分能力;盐渍化土壤盐分变动带位于浅层0~40 cm,且20~40 cm深度的土壤盐分波动幅度较大,深层40~60 cm土壤孔隙水溶液盐分向下运移的通量与土壤体盐分对其的补充量达到动态平衡,水分下渗过程中深层土壤孔隙水盐分含量相对平稳。实验结果为盐渍土的防治提供参考。 相似文献
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Targeted yield concept and a framework of fertilizer recommendation in irrigated rice domains of subtropical India 总被引：1，自引：0，他引：1
Bera R Seal A Bhattacharyya P Das TH Sarkar D Kangjoo K 《Journal of Zhejiang University. Science. B》2006,7(12):963-968
Soil test crop response （STCR） correlation studies were carried out in Vindhyan alluvial plain during 2001 to 2004 taking IR-36 as test crop to quantify rice production in the context of the variability of soil properties and use of balanced fertilizers based on targeted yield concept. The soils were developed on gently sloping alluvial plain with different physiographic settings and notable variation in drainage condition. Soil properties show moderate variation in texture （loamy to clay）, organic carbon content （4.4 to 9.8 g/kg）, cation exchange capacity （10,2 to 22.4 cmol （p＋）/kg） and pH （5.3 to 6,4）, Soil fertility status for N is low to medium （224 to 348 kg/ha）, P is medium to high （87 to 320 kg/ha） and K ranges from medium to high （158 to 678 kg/ha）. Database regarding nutrient requirement in kg/t of grain produce （NR）, the percent contribution from the soil available nutrients [CS （%）] and the percent contribution from the applied fertilizer nutrients [CF （%）] were computed for calibrating and fbrmulating fertilizer recommendations. Validity of the yield target for 7 and 8 t/ha was tested in farmers＇ fields and yields targets varied at less than 10%. The percent achievement of targets aimed at different level was more than 90%, indicating soil test based fertilizer recommendation approach was economically viable within the agro-ecological zone with relatively uniform cropping practices and socio-economic conditions. 相似文献
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黄金萍 《绵阳师范高等专科学校学报》2014,(8):117-119
通过对武夷山进行实地考察,选取了竹林（坳头）,杉木林（桐木关西侧）,茶园（挂墩）3个不同土地利用方式下的土壤剖面,并通过室内理化分析实验,测定剖面土壤的有机质总量、全氮含量及其机械组成,研究土地利用方式对其土壤养分的影响.通过实地考察和室内理化分析实验,得到以下主要结论：（1）竹林、杉木林和茶园的土壤机械组成以壤质土为主;（2）茶园、杉木林、竹林的土壤黏粒含量差别不大;（3）在A层中,不同土地利用方式下土壤有机质含量大小顺序为竹林〉茶园〉杉木林;而在B层中,土壤有机含量大小顺序为竹林〉杉木林〉茶园;（4）在A层中,不同土地利用下土壤全氮含量大小顺序为竹林〉茶园〉杉木林;而在B层中,土壤全氮含量大小顺序为竹林〉杉木林〉茶园;（5）土地利用方式影响着土壤的养分含量,不同的土地利用对土壤养分有着不同的影响. 相似文献
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This paper presents a case study on an ultra-deep diaphragm wall with a depth of 110 m constructed in Ningbo City. The in-situ application shows that using Bauer BC40 cutter machine in conjunction with cutter wheels specified for different strata would be qualified for constructing the 110 m diaphragm wall with high efficiency and precision given that the quality of slurry and poured concrete can be guaranteed. The ground settlement can be effectively controlled by using the overlapping construction method. Sliding failure as a whole characterized by pronounced lateral deformation is likely to occur in the upper muddy clay layer due to its high compressibility and sensitivity. In contrast, local collapse of trench walls tends to happen in the sandy silt strata. Furthermore, careful attention should be paid to sandy silt during the entire construction period as the vertical displacement of the sandy silt continues to develop even after concrete pouring 相似文献
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为探索烤烟中醇、酮两类致香物质质量分数形成的影响因素,在云南省昆明、保山、红河、文山和曲靖等5个烟区,以种植区域、土壤质地和海拔范围3种生态因子为基调进行采样,采用同时蒸馏萃取法、内标法和气—质谱联用分析技术,对K326烟叶中酮、醇两类致香物质组分及其质量分数进行探索.结果表明：1）植烟区域是影响醇、酮质量分数及其总量的主要因素,5个区域中以保山最有利于K326烟叶醇、酮两类致香成分的形成,而其余4个区域差异不大.2）从土壤质地来看,中壤土最有利于烟叶中酮类致香成分的形成,轻粘土和重壤土次之,而醇类物质几乎不受土壤质地的影响.3）从海拔范围来看,海拔1500～1800 m范围比较有利于烟叶醇、酮类致香物质的形成,而海拔1100 ～ 1500m或1800 ～2300m的范围次之. 相似文献
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Ridge culture is a special conservation tillage method, but the long-term influence of this tillage system on soil aggregate-size stability in paddy fields is largely unknown in southwest of China. The paper is to evaluate soil aggregate stability and to determine the relationship between soil organic carbon （SOC） and soil aggregate stability. Soil samples at 0 cm-20 cm layer were adopted from a long-term （16 a） field experiment including conventional tillage： plain culture, summer rice crop and winter upland crop under drained conditions （PUR-r）; and conservation tillage： ridge culture without tillage, summer rice and winter fallow with floodwater layer annually （NTR-f）, winter upland crop under drained conditions （NTR-r）, and wide ridge culture without tillage, summer rice crop and winter upland crop under conditions （NTRw-r）, respectively. Different pretreatments, such as slaking in fast wetting, wetting and subsequent slaking, were applied to simulate the breakdown mechanisms of aggregates in paddy soil. The results show that soil particles contents were mainly consisted of silt （0.050 mm to 1.000 mm） in fraction of 42.9% to 51.2%, sand （0.050 mm to 0.001 mm） in fraction of 28.0% to 31.8%, and clay （〈0.001 mm） in fraction of 17.9% to 25.4%. The amount of aggregate-size was greatly observed in fraction of 2.000 mm-6.720 mm under ridge culture in paddy soil （more than 50$） under slaking and wetting pretreatment. The proportion of soil macro-aggregates （〉0.250 mm） in conservation tillage was greatly higher than that in conventional tillage under subsequent fast slaking treatment. Minimal differences of aggregate stability between slaking in fast wetting and wetting were observed, while significant differences were found between ridge culture and plain culture. The aggregate stability under slaking treatment ranked in the order of NTR-r〉NTRw-r〉 NTR-f 〉 PUR-r, while under wetting was NTRw-r 〉 NTR-r 〉 NTR-f 〉PUR-r. There was a positive correlation between the aggregate stability and SOC concentration under wetting, and a low correlation was observed under slaking pretreatment. Soil exposure with tillage and lack of rice/rape-seed stubble inputs caused declines in aggregation and organic carbon, both of which make soil susceptible to water erosion. Adoption of ridge culture with no-tillage integrated with crop rotation and stubble mulch significantly altered soil organic concentration. It was a valuable conservation practice for soil aggregation and soil organic carbon sequestration on paddy soil. 相似文献
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In a landfill, excessive tensile strains or failure of the liner system due to localized subsidence underneath the geosynthetic liner, is a concern in design and operation of the landfill. The localized subsidence can be commonly withstood by reinforcements such as geogrids. A total of nine model tests were carried out to study the influence of soil arching in overburden sandy soil on the geosynthetics and the interaction between the soil and the geosynthetics. The localized subsidence was modeled by a strip trapdoor under the geosynthetic reinforcements. The reinforcement includes several layers of polyvinylchlorid (PVC) membrane or both PVC membrane and a compacted clay layer. Test results show that the vertical soil pressure acting on the geosynthetics within the subsidence zone is strongly related to the deflection of the geosynthetics. The soil pressure acting on the deflected geosynthetics will decrease to a minimum value with respect to its deflection if the final deflection is large enough, and this minimum value is almost independent of the overburden height. Otherwise, the deflection of geosynthetics cannot result in a full degree of soil arching, and the soil pressure within the subsidence zone increases with the increase of overburden height. Deflections and strains of the geosynthetics obviously decrease with the increase of their tensile stiffness. The presence of a compacted clay layer buffer can therefore reduce both deflections and strains of the geosynthetics. Finally, a composite liner structure is recommended for landfills to withstand the localized subsidences. 相似文献
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紫外光光强对TiO2-膨润土降解十二烷基苯磺酸钠的影响 总被引：1，自引：1，他引：0
在室温、电磁搅拌和6W紫外灯(距静止液面距离分别为6.5 cm、18.5 cm、30.5 cm和42.5 cm)的不同光强(在静止液面处的光强分别为700~750μW/cm2、300~310μW/cm2、200~210μW/cm2和110~120μW/cm2),及太阳光的不同紫外光强度照射条件下,质量分数为0.5‰的纳米TiO2-膨润土复合光催化剂对初始质量浓度为20 mg/L的十二烷基苯磺酸钠(SDBS)溶液中SDBS的降解反应表明:光强对SDBS降解的影响较大,光强越强SDBS的降解率越高、溶液的COD值降低率越大;不同光强下,TiO2-膨润土对SDBS降解反应为一级反应,符合Langmuir-Hinshelwood方程;随着光强的增大,TiO2-膨润土对SDBS降解的光催化反应速率常数增大。 相似文献