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1.
农业机械化对农业贡献率测算方法研究   总被引:41,自引:6,他引:35  
测算农业机械化对农业生产的贡献份额,实践上有助于从总体上把握农业机械化的发展水平、发展潜力和趋势,对农业机械化事业的决策具有重要的参考价值;理论上研究产业系统单因素的贡献率具有学术意义。该文在分析国内外生产率理论和测算方法的基础上,设计了运用柯布-道格拉斯生产函数和项目有无比较法进行农业机械化对农业贡献率的测算方法。  相似文献   

2.
东北农业机械化特点及其对种植业纯收益的贡献率   总被引:5,自引:1,他引:4  
为了研究农业机械化在农业和农村经济中的量化效果,在分析东北农业机械化特点的基础上,用项目有无比较法测算了东北农业机械化贡献率。对主要影响因素进行了分析,提出了有关农业机械化特别是东北地区农业机械化发展的建议。研究结果表明:1998年东北地区农业机械化贡献率为28.74%,特别是在农产品价格下降、种田经济效益不高的情况下,农业机械化的贡献作用更为显著。  相似文献   

3.
用DEA法的两个模型测算农机化贡献率的算法研究   总被引:1,自引:0,他引:1  
测算农机化贡献率的主要目的是从数量关系上认识农机化对农业增产增收带来的实际作用大小。在实践上有助于从总体上把握农业机械化的发展水平、发展潜力和发展趋势,在理论上研究产业系统单因素的贡献率具有学术意义。该文提出了综合运用DEA法的C2R和C2GS2两个模型,测算农机化贡献率的基本方法。该算法克服了现有DEA算法测算农机化贡献率时无法考虑技术进步所做的贡献而导致农机化贡献率偏大的问题,使测算结果更接近真实情况。  相似文献   

4.
农业机械化是我国实现农业现代化的必经之路,能够降低农业成本,节约资源,在促进农业经济增长和农民增收方面起着重要作用。基于此,采用柯布-道格拉斯生产函数和间接贡献率法以新疆1997—2016年统计数据测算农业机械化对农业经济的贡献率,结果表明:农业机械对新疆农业经济的总体平均贡献率为52.23%;所选指标弹性系数之和大于1,表明新疆农业经济处于报酬递增阶段,扩大农业生产规模有助于农业经济的增长。据此得出结论:农业机械化对新疆农业经济有着显著的贡献,但同发达国家还有一段差距,现阶段应该大力推进农业机械化以促进新疆农业经济的增长。  相似文献   

5.
陕西省农业机械化对农业生产贡献率的研究   总被引:23,自引:3,他引:20  
该文运用Cobb-Dauglas生产函数和项目有无比较法,对陕西省1980年以来农业机械化对农业生产的贡献率进行了定量研究,导出农业机械化对农业产出的贡献率计算公式及灰色序列预测模型,并对两种方法的计算结果进行了分析比较。  相似文献   

6.
冯浩  吴普特 《水土保持通报》1998,18(6):54-57,62
采用农业科技进步的贡献率的统一算法,对黄土高原国家攻关试区的农业科技进步贡献率进行了测算,并结合黄土高原试区的特点,对测算结果进行了初步的分析和评价。  相似文献   

7.
农业技术进步贡献率研究综述   总被引:3,自引:0,他引:3  
农业技术进步是农业发展和实现农业现代化的决定力量,对农业技术进步的研究主要从农业技术进步贡献率的测定入手并根据测算结果分析农业技术进步与农业其他方面的相关关系。文章指出目前测算技术进步贡献率的各种方法并分析各种方法研究中存在的问题,以便于更全面的理解和研究技术对农业的贡献。  相似文献   

8.
农业机械化对农业和农村经济贡献率理论分析   总被引:8,自引:2,他引:6       下载免费PDF全文
机械化对农业产出增长的贡献不仅包含农业机械投入量增减对产出的影响,而且应包括农业机械生产率提高的作用,贡献率大小可用农业机械产出弹性在规模弹性中的比值衡量;机械化对农业劳动生产率增长的贡献大小决定于它对农业产出增长的贡献大小和对农业劳动力的替代作用;农业机械化在某一时期对农村经济的贡献与由它产生的劳动生产率增长率成正比,与非农产业产值占农村社会总产值的比重成正比,与初期从事农业的劳动力数量成正比。  相似文献   

9.
黑龙江省种植业机械化发展情况分析   总被引:2,自引:1,他引:1  
为科学的分析种植业机械化发展情况,该文在分析现有农业机械化发展水平评价研究成果基础上,结合黑龙江省实际情况,建立了种植业机械化发展水平评价指标体系,并利用德尔菲法确定了各评价指标的权重,同时参考黑龙江省实现农业现代化时的发展目标,确定了各评价指标的标准值。最后,利用综合评价法测算2001-2008年黑龙江省种植业机械化发展水平,测算结果表明黑龙江省种植业机械化水平从2001年的45.91%增长到2008年的63.24%,平均每年增长2.17%。通过各评价指标的对比研究,分析了阻碍种植业机械化水平发展速度的原因,为指导黑龙江省种植业机械化发展提供科学依据。  相似文献   

10.
李永垚  熊康宁  罗娅 《水土保持研究》2012,19(6):259-263,268
通过论述国家石漠化综合治理工程研究概况,探讨石漠化综合治理艰巨性与科技支撑的关系,概括科技贡献率测算理论的创建和完善过程、科技贡献率的认识、基于国民经济等六个行业的科技贡献率测算,分析石漠化综合治理工程科技贡献率研究存在的问题。指出了C—D生产函数和索洛余值法是当前科技贡献率测算的主要方法,但研究尺度仅限于科技进步对于经济增长的贡献率,缺乏石漠化综合治理技术进步对于区域经济发展、生态环境改善、社会效益提高、民生效益惠及等综合贡献率的测算研究。提出加强石漠化综合治理工程科技贡献率测算研究工作,创建适合于科技进步在经济发展、生态改善、民生惠及的贡献测算方法和模型等建议,以期为科学测算和评价石漠化综合治理工程中科技进步对于区域经济发展和生态恢复与重建的贡献率提供强有力的理论支撑。  相似文献   

11.
低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响   总被引:2,自引:2,他引:0  
【目的】以富士(Fuji)、 秦冠(Qinguan)嫁接在平邑甜茶(Malus hupehensis Rehd.)上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水(ZZ)、 低氮正常水(DZ)、 正常氮干旱(ZG)、 低氮干旱(DG)。氮素和水分均设置两个水平,分别为正常氮(6 mmol/L NO-3-N)、 低氮(0.3 mmol/LNO-3-N)、 正常供水(保持盆中砂子相对含水量为饱和含水量的80%~85%)、 干旱处理(保持盆中砂子相对含水量为饱和含水量的60%~65%)。【结果】富士和秦冠的生物量(茎和叶)、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水(ZZ)>低氮正常水(DZ)>正常氮干旱(ZG)>低氮干旱(DG),并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水(ZZ)>低氮正常水(DZ)>正常氮干旱(ZG)>低氮干旱(DG); 氮、 钾元素含量在植株各部位的分布顺序依次是叶>根>茎,磷元素则是根>叶>茎;光合氮素利用效率(PNUE)和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水(DZ)处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱(DG)处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。  相似文献   

12.
Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.  相似文献   

13.
正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,  相似文献   

14.
Staff members of the Department of Botany of Palacký University in Olomouc and Gene Bank Department – Workplace Olomouc, Research Institute of Crop Production in Prague, Czech Republic, conducted an expedition in seven European countries (Austria, Czech Republic, France, Germany, Italy, the Netherlands, Switzerland) in August/September 1999 to collect wild Lactuca spp. germplasm and study its geographic distribution, ecology and biodiversity. During the mission, more than 600 locations were visited resulting in the collection of 602 seed samples (accessions) of wild Lactuca species and 13 seed samples of related genera (Chondrilla and Mycelis). Lactuca serriola f. serriola, L. serriola f. integrifolia, L. saligna and L. viminea subsp. chondrilliflora were prevalent in southern Europe (Italy, France), however, only L. serriola was common in central and western Europe (Austria, Czech Republic, Germany, Netherlands, Switzerland). The greatest diversity of Lactuca species was found in France, where also the most seed samples (165) were collected. The most characteristic habitats with a high density of Lactuca spp. populations were observed along roads and highways, grassy ditches, ruderal communities, and dust-heaps. Natural infections by powdery mildew (Erysiphe cichoracearum) and downy mildew (Bremia lactucae) on some wild Lactuca spp. were observed. Recent observations concerning the geographic distribution, population structure, habitats, and natural occurrence of diseases of Lactuca spp. are discussed. This assemblage of genetic resources of Lactuca spp. can serve as the basis of future studies of species diversification, spatial population structure, plant microevolution, domestication processes, and genetic variability of host-parasite interactions.  相似文献   

15.
The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.  相似文献   

16.
李聃枫  朱春梧 《土壤》2020,52(3):561-566
自20世纪60年代"绿色革命"以来,育种技术和农耕技术的发展促进了农作物产量的大幅提升,然而作物的营养品质出现下降趋势。在相似的遗传背景下,大气CO_2浓度升高会使单位体积农作物产品的营养元素含量下降,因此"绿色革命"至今,农作物产品的营养元素下降可能受大气CO_2浓度升高影响。通过植物生长箱模拟"绿色革命"初期和目前的大气CO_2浓度水平(310μmol/mol和400μmol/mol),针对主要C_3作物水稻、小麦和大豆,研究"绿色革命"以来大气CO_2浓度升高对其籽粒的C、N、Fe、Zn元素含量的影响,结果表明:CO_2浓度升高对3种作物籽粒的C元素含量几乎没有影响,变化幅度在±1.5%之间;籽粒的N、Fe、Zn元素含量普遍呈现下降趋势,但均未达到显著水平。  相似文献   

17.
Discovery and incorporation of genes from wild species provide means to sustain crop improvement, particularly when levels of resistance in the cultigens are low and virulent strains of pests and pathogens overcome the host plant resistance. The extent of utilization and the potential of the wild genepool for genetic enhancement were reviewed in five important food crops viz. sorghum, pearl millet, chickpea, pigeonpea and groundnut grown in the semi-arid tropics. Introgression from compatible wild germplasm in the primary gene pool resulted in transfer of new cytoplasmic male sterility systems in pearl millet and pigeonpea, development of high protein, cleistogamous flower and dwarf pigeonpea lines and foliar disease resistant groundnut cultivars. Utilization of wild species in secondary and tertiary gene pools has been generally limited due to sterility, restricted recombination or cross incompatibility. Nevertheless, these species are extremely important as they contain high levels of resistance to several important biotic and abiotic stresses. Several of them, like those belonging to the Parasorghum section and the rhizomatous Arachis species are sources of multiple resistances and hold great promise to sustain crop productivity.  相似文献   

18.
Biologically enhanced dissolution offers a method to speed removal of chlorinated solvent dense non-aqueous-phase liquid (DNAPL) sources such as tetrachloroethene (PCE) and trichoroethene (TCE) from aquifers. Bioremediation is accomplished by adding an electron donor to the source zone where fermentation to intermediates leading to acetic acid and hydrogen results. The hydrogen and possibly acetic acid are used by dehalogenating bacteria to convert PCE and TCE to ethene and hydrochloric acid. Reductive dehalogenation is thus an acid forming process, and sufficient alkalinity must be present to maintain a near neutral pH. The bicarbonate alkalinity required to maintain pH above 6.5 is a function of the electron donor: 800 mg/L of bicarbonate alkalinity is sufficient to achieve about 1.2 mM TCE dechlorination with glucose, 1.7 mM with lactate, and a much higher 3.3 mM with formate. Laboratory studies indicate that in mixed culture, formate can be used as an electron donor for complete conversion to ethene, contrary to pure cultures studies indicating it cannot. Various strategies can be used to add electron donor to an aquifer for DNAPL dehalogenation while minimizing pH problems and excessive electron donor usage, including use of injection-extraction wells, dual recirculation wells, and nested injection-extraction wells.  相似文献   

19.
Abstract

A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species.  相似文献   

20.
“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.  相似文献   

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