稻田长期垄作免耕对土壤肥力性状的影响研究

以长期田间定位试验为基本材料,研究了长期垄作免耕对稻田土壤肥力性状的影响.结果表明稻田长期垄作免耕有利于土壤结构的形成,土壤中＜0.01mm土粒团聚度增大,＞0.01mm有机微团聚体和＞0.01mm铁、铝-有机微团聚体所占比例表现为不同程度的提高,＞0.01mm元机微团聚体和钙、镁-有机微团聚体显著下降.免耕10年后,稻田长期垄作免耕土壤表层有机质含量提高,0～10cm土层的有机质含量达47.5g/kg,比常规平作高41.1%,比水旱轮作高51.3%,比试验前增加了89.0%;随着土壤层次的下移,各处理的土壤有机质含量降低.垄作免耕与常规平作和水旱轮作相比,土壤中的氮、磷、钾含量增加,稻田垄作免耕有利于土壤的定向培肥.     

混合像元分离的研究进展

遥感成像中混合像元的产生是不可避免的,它的存在严重影响了遥感影像的解译精度,是传统的像元级遥感分类和面积量测精度难以达到实用要求的主要原因。介绍了混合像元存在的普遍性及对其研究的重要性,重点阐述了线性模型、概率模型、几何光学模型等几种分离方法及其它们各自的特点并对它们目前存在的不足和以后要重点研究的内容进行了讨论。最后,指出了现有研究的不足并对今后研究的重点问题给出了建议。     

烟台市中西部及邻区水库淤积研究

将水库淤积按沉积动力学特征分为河流沉积动力淤积和水库沉积动力淤积2种类型,建立了2种淤积类型的动力模型.水库淤积量的大小按水库因水位下降所出露的淤积物面积进行评估.结合陆地卫星TM图像,对研究区内的30个水库,按淤积程度离差分为3级Ⅰ级,DEPDEV＜-0.3;Ⅱ级,DEPDEV=-0.3～1;Ⅲ级,DEPDEV＞1.对比图像平面数据与实测的水库淤积量数据,发现图像数据与兴利库容以下实测数据协同性好.     

集雨灌溉规划方案灰色关联综合评价模型研究

构建了集雨灌溉工程规划方案评价指标体系，提出了多层次灰色关联综合评价模型，对模型中的有关计算问题作了探讨。运用层次分析法合理地处理了各因子权重分配。最后通过工程实例说明了模型的应用。     

干旱胁迫下白花柽柳抑制性消减文库的构建与分析

白花柽柳(Tamarix albiflonum M.T.Liu.)是一种耐旱性的植物。本实验利用抑制性消减杂交技术(SSH)克隆了白花柽柳多个抗旱相关基因的EST片段,并对这些EST片段进行了分析。     

晋西黄土区小流域泥沙来源分析

以晋西黄土区小流域为研究对象,选择了7个典型小流域,根据14 a的定位观测结果,对流域泥沙来源进行了分析.结果表明,按小流域泥沙来源的地貌部位划分,沟谷地(沟头、沟道和沟坡)产沙量＞沟间地(坡面、梁峁坡)产沙量,沟谷地产沙量占流域总产沙量的60%以上,沟谷地侵蚀模数是沟间地的1.28～2.48倍,坡耕地、裸露地是主要产沙地类.     

重金属迁移与土壤性质的关系

Cu, Zn, Pb and Hg runoff from yellow limestone soil and purple soils and the relationships between the mobility of the heavy metals and the soil characteristics were studied in laboratory using a rainfall simulator. The results showed that the concentrations of soluble Zn in surface runoff were significantly negatively correlated with the contents of < 0.002 mm particles and CEC of the soils, indicating that Zn was mostly adsorbed by clays in the soils. The contents of Cu and Hg in surface runoff were positively related to their contents in the soils. The amounts of Cu, Zn, Pb and Hg removed by surface runoff were influenced by the amounts of soil and water losses and their contents in the soils, and were closely related to the contents of soil particles 1~0.02 mm in size.     

重庆市主城区街道地表物中重金属的污染特征

分析了重庆市主城区街道地表物的基本性质及As、Cd、Cr、Cu、Hg，Ni、Pb，Zn等元索的全置、模拟酸雨（pH4．5）的浸出量。结果表明：各功能区中街道地表物的自然组成均以中等粒径的为主；就元素而言，粒径越细对重金属的贡献率越高；就功能区而言．细粒径与中等粒径的颗粒对重金属贡献率较为接近。街道地表物呈碱性，有潜在的有机物污染。重庆市主城区街道地表物重金属元素含量有较大的差异，受人为活动干扰严重的重金属种类为Cr、Cd、Hg、Cu。内梅罗指数评价结果显示除Ni外，其他元素均有不同程度的污染，各功能区均受到重金属的严重污染。重庆市主城区街道地表物中的重金属只与其中的磷素含量显著正相关。     

黄土高原旱地不同施肥对土壤肥力与产量的影响

Long-term fertility experiments have become an important tool for investigating the sustainability of cropping systems. Therefore, a long-term (18-year) fertilization experiment was conducted in Changwu County, Shaanxi Province, China, to ascertain the effect of the long-term application of chemical fertilizers and manure on wheat yield and soil fertility in the Loess Plateau, so as to provide a scientific basis for sustainable land management. The experiment consisted of nine fertilizer treatments with three replicates arranged in a completely randomized design: 1) CK (no fertilizer); 2) N (N 120 kg ha-1); 3) P (P 26.2 kg ha-1); 4) NP (N 120, P 26.2 kg ha-1-2); 5) M (manure 75 t ha-1); 6) NM (N 120 kg ha-1, manure 75 t ha-1); 7) PM (P 26.2 kg ha-1, manure 75 t ha-1); 8) NPM (N 120 , P 26.2 kg ha-1, manure 75 t ha-1); and 9) fallow (no fertilizer, no crop). N fertilizer was applied in the form of urea and P was applied as calcium super phosphate. The results showed that precipitation had a large effect on the response of wheat yield to fertilization. Manure (M), NP, PM, NM, and NPM treatments significantly increased (P < 0.05) average yield. In the NP, PM, NM and NPM treatments, the percentage increases in yield due to fertilization were highest in normal years, and lowest in the drought years. Long-term P application enhanced soil available P markedly, and manure applications contributed more to soil fertility than chemical fertilizers alone. Chemical fertilizers applied together with manure distinctly improved soil fertility. The results also showed that the soil nutrient concentration changed mainly in the 0--60 cm layers and fertilization and planting only slightly affected soil nutrients below the 100 cm layers.     

不同雨强和坡度条件下紫色土养分流失规律研究

采用室内模拟降雨装置,研究了三峡库区紫色土在不同雨强和坡度条件下的养分流失规律。结果表明,紫色土坡面流失养分主要由径流和泥沙携带,其中径流养分含量与雨强和坡度无关,但与产流过程一致。泥沙中养分含量与雨强无关,但随坡度增加而降低;泥沙养分含量与产沙量过程无关,但其流失量与产沙量过程一致。泥沙中各养分含量略大于降雨前表土养分含量,远大于径流养分含量,但由于径流中以速效养分为主,故径流携带的养分流失量不容忽视。