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古浪县日光温室蔬菜膜下滴灌技术试验研究. 总被引:1,自引:0,他引:1
唐贵年 《甘肃水利水电技术》2008,(7)
结合石羊河流域综合治理,在古浪县已建日光温室蔬菜生产中进行膜下滴灌技术试验研究。结果表明,膜下滴灌能为作物生长发育创造良好的水、肥、气、热等生态环境。使日光温室内土壤层平均温度提高,改善土壤理化性状,减少病虫害发生,可以省水、省肥、省农药,促进蔬菜早熟,达到增产增收之目的。 相似文献
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膜下滴灌技术在漯河市日光温室的应用与效益 总被引:1,自引:0,他引:1
膜下滴灌是一种先进灌水技术,对节水和丰产起着重要作用。文章简明阐述日光温室灌溉技术的发展,膜下滴灌技术的特点以及在漯河市目光温室中的应用与效益。 相似文献
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滴灌条件下不同覆盖模式对新疆棉田土壤水热的影响 总被引:1,自引:0,他引:1
通过测定滴灌条件下不同覆盖模式对新疆棉田土壤水热的影响发现,覆膜对0-30cm土层的保墒效果优于覆秸秆,而膜下秸秆模式对0-100cm土层具有明显保墒作用;铃期是棉花的需水关键期,膜下秸秆模式能够有效缓解龄期需水量大与滴灌供水不足的矛盾;在花期覆膜或覆秸秆能够增加棉田土壤温度,有利于提高棉花的座果率;覆膜能有效应对棉田早期的低温环境,促进棉株生长,而覆秸秆不利于棉花及时成熟,对最终产量及纤维品质产生不利影响;综合分析认为,膜下秸秆模式对棉田的保水保温效果最佳. 相似文献
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介绍了精量灌溉系统自动控制的功能、工作原理,将其用于工程节水和农艺节水相结合的西红柿膜下滴灌中,并与一般覆膜沟灌的种植、生产的投入、产出及节水增效进行了对比分析,结果表明,精量灌溉系统和膜下滴灌技术在政府的支持和帮助下可大面积推广使用。 相似文献
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阐述了膜下滴灌技术的含义特点,总结了膜下滴灌技术的特点和内涵。通过在赤峰市现代节水型灌溉农业中从节水、节肥、节农药、节地、保土、保肥、增温、调温、提高劳动生产率、提高品质、增加产量、降低生产成本、防治盐碱、抗灾能力等方面说明了膜下滴灌技术的优点,同时列举各种实验数据进一步说明膜下滴灌的优越性,证明了膜下滴灌技术在干旱贫水区重要地位和作用,展示出了膜下滴灌技术的广阔发展前景,值得推广应用。 相似文献
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膜下滴灌是一种新型的节水灌溉方法,利用该节水方法可以实现水肥同步,能够使蔬菜根充分吸收自身生长需要的营养和水分,使蔬菜的产量不断提高,针对大棚蔬菜膜下滴灌优点、节水技术及应用技术等进行阐述和分析,为棚蔬菜膜下滴灌的推广提供指导依据. 相似文献
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根据冗各电站地下厂房开挖支护的施工顺序,以隐式杆单元模拟锚杆,以壳单元模拟混凝土喷层,采用三维非线性有限元技术,对洞室群的开挖支护动态过程进行了模拟计算。通过三维非线性有限元计算分析得到:洞室群动态开挖过程中围岩应力变形的分布规律,围岩塑性区的发展规律,锚杆受力变化情况。计算结果表明:整个开挖过程中,洞周围岩位移变化规律正常,量值较小,塑性区主要分布在洞室周边,围岩稳定性较好;但在洞室交叉口处围岩的变形较大,出现较大范围的塑性区,在此基础上提出了支护措施优化方案,并对优化方案的效果进行了评价。 相似文献
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The relocation of unionacean mussels is commonly used as a conservation and management tool in large rivers and streams. Relocation has been used to recolonize areas where mussel populations have been eliminated by prior pollution events, to remove mussels from construction zones and to re-establish populations of endangered species. More recently, relocation has been used to protect native freshwater mussels from colonization by the exotic zebra mussel Dreissena polymorpha. We conducted a literature review of mussel relocations and evaluated their relative success as a conservation and management strategy. We found that 43% of all relocations were conducted because of construction projects that were forced to comply with the Endangered Species Act 1973 and that only 16% were monitored for five or more consecutive years. Most (43%) relocation projects were conducted from July to September, presumably a period when reproductive stress is relatively low for most species and the metabolic rate is sufficient for reburrowing in the substrate. The mortality of relocated mussels was unreported in 27% of projects; reported mortality varied widely among projects and species and was difficult to assess. The mean mortality of relocated mussels was 49% based on an average recovery rate of 43%. There is little guidance on the methods for relocation or for monitoring the subsequent long-term status of relocated mussels. Based on this evaluation, research is needed to develop criteria for selecting a suitable relocation site and to establish appropriate methods and guidelines for conducting relocation projects. 相似文献
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Samples were taken year-round at eleven sites along the altitudinal profile (2900-1400 m a.s.l.) of the Gunnison River, a 329 km tributary of the Colorado River, to document the distribution of the Plecoptera and to evaluate responses to hypolimnial-release dams in the headwaters and middle reaches. Twenty-two species were present, with the greatest species richness occurring in an unregulated segment upstream of the middle reach dams; average nymphal biomass over the study period (175 organisms, 395 mg dry mass m?2) was also greatest in this segment. Only four species (58 organisms, 48 mg m?2) were present in the tailwaters of the headwater dam and values were greatly reduced (nine species; 35 organisms, 180 mg m?2) below the middle reach dams. The stonefly community recovered ca. 80 km downstream from the last dam (15 species; 244 organisms, 250 mg m?2), apparently in response to natural resetting of environmental conditions corresponding to those above the middle reach dams. At the most downstream site (11) only four species (four organisms, 16 mg m?2) were present. The observed distributional pattern is a classic serial discontinuity in response to hypolimnial stream regulation in a temperate latitude river. 相似文献
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In the lower River Murray, Australia, populations of gastropods have declined markedly over the past 40 years. Of the native fauna of about 18 species, only the ancylid Ferrissia petterdi remains common (but in patches), and another five species feature in sporadic local resurgences. Until recently the viviparid Notopala was thought to be extinct. The introduced physid Physa acuta is widespread, but in low numbers. The decline probably is associated with flow regulation, high turbidity and the introduction of common carp. Snail populations have persisted, however, in irrigation pipelines fed from the river, where they periodically cause blockages. This paper reports the discovery of the only known populaion of Notopala hanleyi in a pipeline where the inner wall accumulates microbial and other organic matter, providing high quality food for snails. In the Murray before regulation most of the periphytic biomass was probably microbial, as fluctuating water levels would have maintained littoral communities in a highly productive, early state of succession his postulated that, by stabilizing seasonal water levels, regulation has promoted the production of filamentous green algae, an inferior food source, and so displaced snail populations from the open aquatic environment. 相似文献
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V. K. Konovalov O. V. Yashkin V. V. Ermakov 《Power Technology and Engineering (formerly Hydrotechnical Construction)》2008,42(2):105-109
A system for removal and pneumatic transport of fly ash is examined, in which air pulses act on batches (pistons) of ash formed
in a duct. Studies are made of the effect of several physical parameters on the force required to displace a piston of ash
and these serve as a basis for choosing a system for removal and pneumatic transport of ash simultaneously from several hoppers
of an electric precipitator. This makes it possible to separate the ash particles according to size without introducing additional
components. Formulas are given for calculating the structural and dynamic parameters of this system and measurements of indirect
dynamic parameters are used to calculate the input-output characteristics of the system. In order to optimize the system,
configurations for summing several ducts into a single transport duct for pneumatic ash transport are proposed. Some variants
of dry ash utilization and the advantages of producing of size-separated particles are considered.
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Translated from élektricheskie Stantsii, No. 2, pp. 26–30 (2008). 相似文献
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Peter B. Bayley 《河流研究与利用》1991,6(2):75-86
The ‘flood pulse advantage’ is the amount by which fish yield per unit mean water area is increased by a natural, predictable flood pulse. Evidence for this increase is presented from tropical and temperate fisheries. It is argued that increasing multispecies fish yield by restoring the natural hydrological regime is consistent with increasing production of other trophic levels and with restoration from ecological and aesthetic viewpoints. When applied to a river-floodplain system, this restoration would provide a large, self-sustaining potential for recreation, commercial exploitation, and flood control. An interim ‘natural flood pulse’ restoration approach is proposed for systems modified for navigation. This approach approximates the natural hydrological regime in a river reach and is intended as a first step in the long process of restoring the watershed. 相似文献