Eight years of annual no-till cropping in Washington's winter wheat-summer fallow region

The tillage-based winter wheat (Triticum aestivum L.)-summer fallow (WW-SF) cropping system has dominated dryland farming in the Pacific Northwest USA for 125 years. We conducted a large-scale multidisciplinary 8-year study of annual (i.e., no summer fallow) no-till cropping systems as an alternative to WW-SF. Soft white and hard white classes of winter and spring wheat, spring barley (Hordeum vulgare L.), yellow mustard (Brassica hirta Moench), and safflower (Carthamus tinctorius L.) were grown in various rotation combinations. Annual precipitation was less than the long-term average of 301 mm in 7 out of 8 years. Rhizoctonia bare patch disease caused by the fungus Rhizoctonia solani AG-8 appeared in year 3 and continued through year 8 in all no-till plots. All crops were susceptible to rhizoctonia, but bare patch area in wheat was reduced, and grain yield increased, when wheat was grown in rotation with barley every other year. Remnant downy brome (Bromus tectorum L.) weed seeds remained dormant for 6 years and longer to heavily infest recrop winter wheat. There were few quantifiable changes in soil quality due to crop rotation, but soil organic carbon (SOC) increased in the surface 0–5 cm depth with no-till during the 8 years to approach that found in undisturbed native soil. Annual no-till crop rotations experienced lower average profitability and greater income variability compared to WW-SF. Yellow mustard and safflower were not economically viable. Continuous annual cropping using no-till provides excellent protection against wind erosion and shows potential to increase soil quality, but the practice involves high economic risk compared to WW-SF. This paper provides the first comprehensive multidisciplinary report of long-term alternative annual no-till cropping systems research in the low-precipitation region of the Pacific Northwest.     

金华市石门农场生态农业建设及其效益分析

金华市石门农场自１９８６年起进行生态实验区建设，将饲养、种植、加工三个子系统有机结合成一个整体，形成以种植业为基础，饲养业为中心，沼气为纽带的能量、物质循环利用的复合型结构，取得了较好的经济和生态效益。从而提出了江南低丘红壤区生态农业建设的一种模式。     

Cues used by shiny cowbirds (Molothrus bonariensis) to locate and parasitise chalk-browed mockingbird (Mimus saturninus) nests

Unlike other birds, shiny cowbirds (Molothrus bonariensis) must locate host nests where to lay their eggs and then decide whether to parasitise them. They should also synchronise their laying with that of the host to increase the survival of parasite egg and young. Shiny cowbirds can discover nests using host behaviour as a cue, or by searching the habitat without need for the presence of a host. Besides, they can synchronise parasitism with host laying by monitoring nests during building and laying, or directly by assessing the degree of development of embryos through the puncture of host eggs. Alternatively, synchronization can arise by lower nest attentiveness during host laying. We determined the extent of synchronization between laying of shiny cowbirds and chalk-browed mockingbirds (Mimus saturninus) and estimated if parasitism was negatively associated with host nest attentiveness. We also conducted an experiment to test if host activity was necessary to locate nests, and if puncture of host eggs was a cue for deciding parasitism. Shiny cowbirds synchronised parasitism with host laying in 75% of the cases and synchronization was not explained by lower host nest attentiveness during laying. Shiny cowbirds located nests without need for presence of a host, but the decision of parasitising the nest depended on host activity at the nest. The information that shiny cowbirds could obtain through egg punctures was not necessary for deciding parasitism. Our results indicate that shiny cowbirds rely on the precise timing of their eggs and avoid laying in unsuitable nests.     

Investigation of fault position and sources of radon by measurement of 238U decay series radionuclide activity in soil samples

North Derbyshire is designated a Radon Affected Area by the National Radiological Protection Board of Great Britain since more than 1% of the housing stock is estimated to have radon levels in excess of the 200 Bq m-3 Action Level. Enhanced radon emissions associated with geological faults make knowledge of their position important in relation to any potential residential or industrial development. A general survey of radionuclides present in the soils of north Derbyshire and their relationship to the underlying geology highlighted the difficulty of identifying the position of geological faults in the field. Using gamma-ray spectroscopy of soil samples the activity of three 238U decay series radionuclides (226Ra, 214Pb and 214Bi), which were taken as evidence of the presence of 222Rn which occurs in the same decay series, was measured to indicate the position of a fault by enhanced activity. The results also provided some evidence of the source of radon emitted at the fault. A comparison of this methodology with the more conventional soil gas analysis method is made.     

邻苯二酚2,3-双加氧酶基因克隆、定位和高效表达

采用特异性引物，以菲、芘降解菌株ZL5的代谢性质粒为模板，扩增出邻苯二酚2，3—双加氧酶(C23O)基因，将该基因和表达载体pET—30a( )连接，转化E.coli JM109(DE3)，获得了高效表达的转化子，SDS—PAGE结果表明，转化子的C23O蛋白不仅在细胞内存在，而且能被分泌到胞外，薄层扫描显示，转化子细胞内和细胞外表达蛋白总量占细胞总蛋白的42％，酶活分析表明，分布在转化子细胞内、外的表达蛋白都具有较高的C23O比活力，Southern杂交将菌株ZL5的C23O基因定位在内生质粒的不同酶切片段上。图5表1参12。     

双衬层填埋场渗漏检测电极铺设方式研究

利用高压直流电法对双衬层填埋场渗漏检测进行了研究.结果表明检测电极的铺设方式以及供电电极和参比电极的位置对漏洞定位有一定影响.在回路电流、检测电极间距、定位算法、介质分布相同的条件下,三角形的检测电极铺设方式比四边形的漏洞定位误差小,且不同点的误差波动小.当参比电极距离漏洞较近时,漏洞定位误差较大;而参比电极与漏洞的距离越大,漏洞定位误差则越小.同时,检测层的电势分布主要是由供电电极和漏洞造成,因此,参比电极的位置既要远离漏洞又要远离供电电极.     

Relationships between Danish organic farming and landscape composition

This article presents an investigation of relationships between organic farming and landscape composition in Denmark. Landscape composition was analysed in terms of density of uncultivated landscape elements (I), number of land uses per hectare (II), diversity of land use (III) and mean field size (IV). Two analytical approaches were used. The first was based on an examination of the national agricultural registers for 1998, 2001 and 2004. The second approach used aerial photo interpretation for an analysis of 72 conventional and 40 organic farms within three sample areas for 1982, 1995 and 2002. The national analysis indicated that organic farming has a direct effect on landscape composition. In 2001, organic farms were characterised by a higher number of land uses per ha, a higher land use diversity and smaller mean field sizes. From 1998 to 2004, conversion to organic farming was related to an increasing number of land uses per ha, increasing land-use diversity and decreasing mean field sizes. Relationships between organic farming and landscape composition were independent of variations in regional location, farm size or farm size change. At the level of sample areas, a significant relationship between organic farming and landscape composition was only found for densities of small biotopes. However, when differences in farm size and physical geographical conditions between conventional and organic farms were taken into account, several significant differences in landscape composition were clarified in two of the three sample areas. Furthermore, changes in landscape composition following conversion to organic farming were largely biased by the characteristics of the sample areas. Thus, in contrast to the national level, the sample area study indicated that differences in landscape composition between organic and conventional farms were not a direct implication of organic farming practices, but were related to variations within other parameters and to the location of organically farmed land.     

Spatial Pattern Analysis of Regional Water Use Profile Based on the Gini Coefficient and Location Quotient

Water resources have become a barrier hampering socioeconomic development. Changes in the spatial distribution of water use profile have direct impacts to regional water use efficiency. However, the related research is inadequate, and a more suitable way to analyze regional water use profile is necessary. The Gini coefficient and location quotient, two reliable methods commonly used in discussing the spatial distribution of elements, were introduced and calculated. Taking Gansu Province as the study area, the concentration effect of industrial water use was the strongest, followed by domestic, environmental, and agricultural water use. However, a balanced distribution of agricultural water use failed to be coordinated with the production conditions, the center of Gansu’s grain production should be established to enhance the scale effect of agricultural production. The industrial agglomeration effect remained weak, and each region’s dominant industries need to be developed vigorously. Gansu’s domestic water use was consistent with its population distribution, but it is necessary to reduce the water use gap between urban and rural areas. With a growing awareness of environmental protection, environmental water use exhibited a more balanced distribution. Overall, the methods are simple and have good applicability, and the results can provide a reference in water use optimization.     

基于D-S证据理论的“丝绸之路旅游带”5A景区区位优势度测评

景区发展与其区位条件密切相关,处于优势区位的景区更容易获得优先快速发展。以“丝绸之路旅游带”为例,综合考虑资源、市场、交通及服务四大区位因子,将其视为证据,引入D-S证据理论对景区区位优势进行测度,以I~V级表征区位由优到劣的状态,最后对景区区位与旅游发展核心区进行对比。结果显示：（1）区位优势等级区域差异化显著,总体呈现由东南至西北逐级递减的空间分布规律,自I至V级,重心逐步向西北方向偏移。（2）各区位因子分布存在差异性,东南地区景区资源区位优于西北地区;市场区位地带间差异最为明显,存在“长尾”特征及陕西“一省独大”现象;交通区位内在差异性与区位优势相仿;服务区位已不再是制约景区区位的主要因子,但就单个省份来看,“核心—边缘”结构较为明显。（3）与景区旅游发展对比来看,二者具有明显的空间关联性,但仍存在一定程度的空间错位现象。     

基于多目标分布估计算法的地铁网络化应急站点选址

为提升地铁网络的应急救援能力,提出兼顾地下和地面交通两种运输方式的应急资源网络化共享模式,并建立多目标优化模型,对应急站点进行优化选址。模型以应急站点数量最少和总响应时间最短为优化目标,地铁车站重要程度为关键因素,求解各地铁车站的优化覆盖方案。提出了一种多目标分布估计算法,该算法采用拥挤比较算子和锦标赛选择算法获取优势群体,借助概率模型描述可行解的离散分布,并不断更新概率模型来实现种群的进化。运用建立的模型和算法求解北京市局部地铁网络应急站点选址问题,最终获得满足地面交通运输时效、并符合问题优化目标的Pareto最优解集。与NSGE-Ⅱ算法相比,多目标分布估计算法提前123代开始收敛,且针对最小化问题,多目标分布估计算法最优解的两个目标函数值较NSGE-Ⅱ算法分别减小64%和29%。可见,模型符合地铁应急站点选址问题的决策规则;多目标分布估计算法有效地缩小了决策空间,它比NSGE-Ⅱ算法更快地收敛,且能够获得更为优化的应急站点选址方案。