镉处理对大豆生物量及镉分布状况的影响

通过对红壤和河潮土2种土壤的加Cd^2＋盆栽试验，研究了添加不同外源Cd^2＋（0．00，0．25，0．50，2．50，5．00，10．0，20．0mg／kg）对大豆生长发育及镉分布状况的影响．结果表明，（1）2种土壤加Cd^2＋处理，对大豆株高具有抑制作用，河潮土加Cd^2＋处理，大豆生物产量及籽粒产量均以添加0．25mg／kg时最高，添加Cd^2＋≥0．50mg／kg时则表现为抑制作用；红壤加Cd^2＋处理，对大豆生物产量有抑制作用，但添加0．25mg／kg时可促进籽粒的发育．（2）红壤加Cd^2＋处理对大豆营养生长及生殖生长的胁迫作用大于添加相同Cd^2＋处理的河潮土，红壤添加Cd^2＋2．50mg／kg时，大豆株高、生物产量及荚果数等均显著低于对照，而河潮土加Cd^2＋量则为10．0mg／kg，表明红壤对镉污染的环境容量比河潮土低．（3）大豆幼苗期根部Cd^2＋含量高于地上部，而Cd^2＋积累量则受生物产量的影响．在Cd^2＋添加量相同的条件下，河潮土大豆地上部生物产量高于红壤，地上部Cd^2＋积累量及转运率也高于红壤，河潮土Cd^2＋的转运率为50．3％～80．4％，红壤则为45．5％～66．0％．大豆吸收转运到地上部的Cd^2＋主要分布在茎和叶中，荚壳和籽粒中相对较少，大豆地上部各器官中Cd^2＋含量的高低依次为茎、叶、荚壳、籽粒．     

基于土壤剖面质地构型的土壤质量评价——以河南省封丘县为例

土壤剖面质地构型是土壤质量和土壤生产力的重要影响因子,对冲积平原地区来讲尤其重要。然而,现有的土壤质量评价研究中,很少采用该因子,且评价指标筛选大多缺乏明确的生物学意义。本研究利用河南省封丘县39个剖面数据及113个土钻样点数据,使用模糊C均值聚类方法 (FCM)结合Kriging插值方法获取的9种土壤剖面质地构型在空间上分布的单一类别隶属度图;在此基础上结合专家知识,针对平原地区旱作作物及耕地的耕性对土壤剖面质地构型的性状进行打分,以分值为参照,在Arc GIS 9.2中9个单一类别隶属度栅格文件进行栅格计算,获取了研究区土壤剖面质地构型栅格的综合分值。利用包括土壤剖面质地构型在内的多个土壤属性,结合作物产量数据,使用主成分分析(PCA)方法确定了最小数据集(MDS);应用指数和法,基于两种途径对土壤质量进行了评价,并结合测产获取的作物产量对两种评价结果进行了对比分析。结果表明:土壤质量指数与作物产量有较好的相关性,土壤质量评价结果能够较好地反映研究区的土壤质量状况。在添加剖面质地构型因子后,土壤质量评价结果有进一步的改善,可见在黄河泛滥冲积平原地区,剖面质地构型是土壤质量评价必不可少的因子。     

呼和浩特市东达小镇住宅冲积扇园林绿化措施

文章通过对冲积扇立地条件庭院绿化施工,采取一些有效的措施,成功地解决了高寒、干旱区松散岩、卵砾类土壤绿化难题,达到了美化、绿化的优质效果。     

制种玉米连作恒量施磷对灌漠土与潮土中磷素利用的影响

[目的]研究恒量外源磷施用对玉米种子生产的影响,为合理施磷提供依据。[方法]通过大田定位与实验室分析相结合,选用河西走廊石灰性潮土及灌漠土定位施肥。[结果]制种玉米连作8a,恒量磷二铵525kg/(hm^2·a)施用,除无机态二钙磷(Ca_2-P)外,2种不同土类总磷(T-P)、速效性磷(Av-P)、总无机磷(T-IP)、总有机磷(T-OP),以及其他各分级无机、有机磷组分均显著增加。无机磷占全磷总量65.2%~70.2%,有机磷占全磷总量6.5%~11.4%。无机磷中十钙磷(Ca₁₀-P)>八钙磷(Ca8-P)>铝磷(Al-P)>铁磷(Fe-P)>闭蓄态磷(O-P)。有机磷中活性有机磷(MLO-P)>高稳性(HRO-P)>中稳性有机磷(MROP)>活性有机磷(LO-P)。随连作年限增加,灌漠土Ca₁₀-P在连作第5a达到最大,Al-P,O-P均持续增加;潮土Ca₁₀-P持续增加,Fe-P,O-P在连作第5a达到最大,磷增加量为3.94%~37.28%。0—60cm土层,两种土类无机磷各组分含量均呈现由表层至下层递减特点,但不同分级磷在不同土层所占比例不同,Ca₁₀-P,Al-P,O-P,MRO-P底聚,Ca_2-P,HRO-P表聚,制种玉米连作生产8a,磷肥最大表观利用率为4.89%,磷素活化系数<2%,外源磷肥以174.3kg/(hm^2·a)残余在土壤中。[结论]制种玉米连作,总磷转化率低,磷素移动缓慢,大部分以溶解性较低的磷素形态在土壤表层积累,但随连作年限增加,土壤对磷素的固持及转化率下降,表现底聚趋势,对生态环境健康存在极大风险,应减量或停止施磷。潮土磷肥施用应采取更加合理措施。     

2种草本植物根系对崩岗洪积扇土壤分离的影响

为探讨草本植物根系对崩岗洪积扇土壤分离的影响,以宽叶雀稗(Paspalum wettsteinii)和巨菌草(Pennisetumsp.)为研究对象,采用变坡水槽冲刷试验,研究种植草本植物后土壤分离的变化特征及影响因素。结果表明:各土层平均土壤分离速率大小为裸地(69.93g/(s·m2))宽叶雀稗(57.42g/(s·m2))巨菌草(43.28g/(s·m2)),且不同植被土壤分离速率均随着土层的加深呈幂函数增加;根长密度是影响土壤分离最重要的根系指标,宽叶雀稗小区土壤分离速率随各根系参数指标的增大呈对数函数下降,而巨菌草区则表现为幂函数下降,体现了不同植被根系构型对土壤分离效应的差异;2种草地土壤分离速率可以用水流剪切力、土壤抗剪强度和根长密度很好的模拟(NSE≥0.90)。研究结果可为崩岗治理措施的配置提供科学依据。     

Characteristics and mineralogy of desert alluvial soils: Wadi Zegrir,Northern Sahara of Algeria

Few studies on the characteristics and mineralogical trends of the soils in the Sahara Desert have been reported in the literature. This work aims at studying the morphology, the classification, and the mineralogy of desert alluvial soils of the Mzab region in the Northern Sahara, Algeria. Morphological and analytical studies carried out on fourteen pedons of wadi Zegrir over a range of elevations (250–850?m) indicate that the soils are sandy to silty clay, nonsaline (electrical conductivity, EC?alluvial and aeolian processes in which evaporite tertiary and secondary formations play an important role in the formation of contemporary minerals. Thin-section observations revealed that the occurrence of calcite in these soils is related to allochthonous mechanisms and in situ crystallization. X-ray diffraction analysis indicates that palygorskite and illite are present throughout the clay fraction of the soil samples in all studied profiles. Kaolinite and chlorite are less abundant, whereas smectite is present in minor amounts.     

长沙市郊蔬菜土壤重金属含量及其与土壤肥力的关系

为了解蔬菜土壤重金属含量与土壤肥力的关系,通过田间采样方法,对长沙市郊红菜园土和冲积菜园土O～20cm表土共计290个样品中Cu、Cd、Pb、Zn、CT、As、Hg7种重金属元素含量以及土壤pH、有机质、碱解氮、速效磷、速效钾、全氮、全磷、全钾8个肥力指标的含量进行了分析。结果表明：Cd、Pb、Zn、As4种元素含量红菜园土高于冲积菜园土,Cr和Hg则是冲积菜园土高于红菜园土,Cu在两种菜园土中含量相当;7种重金属元素含量的变异系数两种菜园土壤均以Cd元素的最大。两种菜园土中cu与cd、Ph、zn,cd与Pb、cr,Ph与zn之间均表现为显著以上正相关关系;而Hg与cu、cd之间不表现相关关系;重金属元素之间的显著相关性冲积菜园土多于红菜园土。重金属元素含量与肥力指标之间均能建立一定回归方程,且达显著以上水平;土壤有机质是影响重金属积累的主要因素。     

Tropical alluvial forest fragmentation in the eastern lowlands of Colombia (1939–1997)

Alluvial forests are under high pressure from human activities because of their value as agricultural, wildlife, timber and recreational land. Despite this, spatial patterns of alluvial forest deforestation are not well known. We studied forest alterations in a 2800 ha alluvial ecosystem using aerial photographs. During the study period (1939–1997), forests with canopy heights greater than 15 m (high canopy mature forest; HCM forest) decreased by 70·4 per cent while forests with canopy heights less than 15 m (low canopy mature forest; LCM forest) forests decreased by 51 per cent, producing a highly fragmented landscape. Factors responsible for forest change included human activities and river dynamics. Although most of the deforestation was related to human disturbance, almost 27 per cent of forest losses were due to channel migration of the Meta River. HCM forests were the most affected land cover since they are easily accessed, viable for logging and occurred on fertile soils, which are valuable for agriculture. LCM forests were less affected since their soil fertilities and inundation regimes were unfavourable to human uses, and thus, less prone to anthropogenic disturbances. Copyright © 2006 John Wiley & Sons, Ltd.     

大青山冲积平原区农田防护林体系的构建及效益研究

在内蒙古大青山山前冲积平原区构建农田防护林体系,根据立地条件类型选择新疆杨、北京杨、合作杨、群众杨、白柳、旱柳、垂柳等适应性强、生长快的优良品种,采用了适当的抗旱造林技术措施。经测定得出:造林成活率为95%-99%、保存率为95%以上;从2000—2003年营造的农田防护林带均已进入速生期,林带的平均高为9.1 m,平均林带树冠高7.6 m,平均冠幅2.6 m×2.5 m;同时防护林带均发挥出了明显的防风、降温及增加湿度的生态功能。