民国中期(1927～1937年)影响农业生产的因素——以华北地区为例

通过对农地灌溉、农业技术的推广、农业生产资料的投入3个方面的考察,分析了这些因素对农业尤其是对农业产量的影响。

Effect of Irrigation on Groundwater Dynamic Change in the Typical Irrigated Area of Qinghai Province

Under the influence of the natural and human factors, water table of irri- gated area Changes frequently, but it is mainly affected by irrigation water infiltration replenishment during the irrigation. 5 groundwater observation wells were constructed in experimental plot of the Daxia irrigated area to carry out the experiment of the effect of irrigation on groundwater dynamic change in this research. The results showed that the groundwater stage dynarnic change rule of spring and seedling irri- gation stage in the typical plot was fit to the hydrological geology condition of grade- I terrace of Huangshui river valley. On the whole, lateral canal water direction formed a line effect. The No. 1 and No. 2 observation well were the closest to the lateral canal, which received more supplies, and the water level was the highest; the No, 3 observation well took the second place; The No. 4 and No. 5 observation well accepted least supplies, and the water level was the lowest. The rangeability of water table of spring irrigation period was significantly higher than that of seedling irrigation period, this is mainly due to the difference value of intake water volume and drainage water volume of spring irrigation phase was significantly higher than the seedling irrigation phase.

中亚五国棉花和冬小麦需水量的变化及预测

农业灌溉用水是中亚地区最主要的水资源利用方式,灌溉用水量的变化直接影响中亚地区水资源消耗量,进而影响水资源管理和配置。作物需水量是衡量农业灌溉用水量的直接指标,为此本文以中亚主要作物棉花和冬小麦为研究对象,分析了2006—2015年中亚地区灌溉农业用地,以及棉花和冬小麦的需水量变化,并利用CAMarkov方法预测了2030年灌溉农地的变化,进而分析了未来中亚地区农业需水量的状况。研究表明,2006—2015年,中亚地区灌溉农田面积总体增加492km2,其中哈萨克斯坦、吉尔吉斯斯坦和土库曼斯坦均有所增加,但塔吉克斯坦和乌兹别克斯坦有所减少。2006—2015年,棉花需水量只在土库曼斯坦和哈萨克斯坦东部地区显著增加(2.5~4.3 mm·a^-1),在吉尔吉斯斯坦显著减少,并且是唯一呈现总体减少趋势的国家。冬小麦需水量在土库曼斯坦明显增加(10.0mm·a^-1)。至2015年,土库曼斯坦的棉花总灌溉水量增幅最大(3.44%),其他4个国家变化较小。中亚五国冬小麦的总灌溉水量均呈上升趋势;2030年,土库曼斯坦是唯一灌溉农业用地增加的国家,棉花和冬小麦的总灌溉水量均明显增加,棉花灌溉水量增加约28km^3,冬小麦增加约17 km^3。

水泵串并联运行在山区泵站技术改造中的应用

针对陕西省延安地区泵站设备陈旧、装置效率低、耗能高、规划设计不够合理等问题 ,采取了水泵串并联运行的技术改造措施 ,采用三种不同形成的串并联方式 :(1)两泵串联 ,两泵流量尽量相等 ,扬程高的水泵作为二级泵适用于水源条件差的地方 ;(2 )两泵低处并联高处串联 ,两泵宜流量相等 ,扬程相等 ,应有满足两泵水量的水源 ;(3)水泵高处串联 ,低处分别送水灌溉 ,适用一泵或二泵流量的水源 ,此情况必须两泵流量相等 ,扬程高的作为二级泵 ,采用该措施后 ,提高了装置效率 ,降低了能源单耗 ,缩短了轮灌周期 ,扩大了灌溉面积 ,经济效益十分显著。

Development of Magnesium-Dominant Soils Under Irrigated Agriculture in Southern Kazakhstan

Irrational irrigation practices in the Arys Turkestan Canal command area in the southern part of Kazakhstan have led to the formation of soils with poor physical and chemical properties. To study whether irrigation and leaching practices and/or groundwater rise have contributed to the accumulation of Mg2+ on the cation exchange complex of these soils, historical changes in soil and groundwater quality were used as source data and the Visual MINTEQ model was applied to analyze the chemical composition of water and soils in the study area. The imposed irrigation regime and the leaching of light sierosem soils led to the dissolution and subsequent leaching of inherent gypsum and organic matter from the soil profile. Further, the domination of bicarbonate in the irrigation water promoted weathering of the carbonate minerals present as calcite. The higher concentrations of Mg2+ in comparison to Ca2+ in the irrigation water resulted in the replacement of Na+ by Mg2+ on the cation exchange complex. In the lower part of the command area, shallow groundwater has contributed to the accumulation of Na+ and to a large extent of Mg2+ on the cation exchange sites.

Measuring the Condition of Saline Wetlands Threatened by Agricultural Intensification

The saline wetlands,or'saladas',of Monegros Desert,NE Spain,contain biodiversity that depends on the estab- lishment of a prognostic monitoring system that can warn of approaching irreversible damage.In the context of a lack of existing biodiversity inventories for the saladas,we determined their state of conservation and vulnerability using seven physical indicators:escarpment continuity,cropping,stone dumping,size,water occurrence,distance to roads,and proximity to irrigated areas.These features were combined into three meaningful indexes,i.e.,conservation,current vulnerability,and future vulnerability,thus creating an assessment of the preservation or degradation of saladas in the context of encroaching agricultural irrigation projects.The proposed indexes produced consistent results and showed that a great number of the Monegros wetlands were threatened,regardless of their size or frequency of water occurrence.Only 20% of the saladas studied were classified as being in a good or very good conservation,whereas 50% were in bad or very bad shape.A high current vulnerability was found for 60% of the saladas.For saladas located in land to be irrigated, we predicted that 73% would have a high or very high future vulnerability.Currently,58% of the saladas were in bad or very bad condition and fully 65% of the saladas,variable in size,presented a bad or very bad prognosis.Our approach provides a monitoring strategy for the conservation of saline wetlands threatened by agricultural intensification,especially irrigation.

Earth Observation as a Support to Improve Water Use in Irrigated Agriculture

By the end of sixties, several satellites were launched to observe the earth; among them the Landsat missions have been important to study natural resources, especially in agriculture. Currently, Landsat 7, with some problems, and Landsat 5 are useful to evaluate crop development. A project called ＂Participatory multi-Level EO-assisted tools for Irrigation water management and Agricultural Decision-Support＂ （PLEIADES） was financed by the European Commission. This project considers eleven countries and 23 research institutions, Mexico being one of the selected countries. Landsat images are a basic tool of this project. Some of the results obtained in this study are presented in this article. By using w^getation indices obtained by the combinations of reflectances in different bands of the electromagnetic spectrum, it has been possible to estimate the behavior of several biophysical parameters of crops which are used to evaluate plant development, water stress, spatial soil variation, and the effect of plagues and crop diseases. To facilitate this process, a visor was developed, named SPIDER （System of Participatory Information Decision support and Expert knowledge for River basin management） whose use in this work is explained.

Economic Evaluation of the Resource-Saving Technologies in Non-irrigated Lands

Conservation agriculture （CA） is especially relevant for Uzbekistan＇s agriculture, particularly in non-irrigated lands where soil fertility has been steadily declining and the risk of crop failure has been growing. CA has three main characterizations given in scientific literature, which are the minimal soil disturbance, crop rotation and surface crop residue retention. Nowadays, the majority of farmers are not widely using CA in their agricultural practices in Uzbekistan. Maybe, this is due to different perception of the economic efficiency of CA. The objective of the research was to calculate economic efficiency of CA in non-irrigated lands and to show whether it is effective or not in agricultural production. To achieve this objective, literature review including a variety of secondary data is employed. Overall, the costs of labor and fuel consumption per ha at CA technology are less in comparison with conventional technology. Using CA practices gives a chance to increase labour productivity, to use resource effectively and to improve soil quality and crop diversification.