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1.
The impacts of climate change on agriculture are still shadowed with uncertainty. However, climate change is expected to adversely affect Iran's agricultural practices through changes in precipitation, temperature and carbon dioxide fertilization. Therefore, adaptation of this sector to the increasing weather events is imperative. This study is aimed to document the likely impacts of climate change on Iran's agriculture and the current adaptation efforts made by government and farmers. The review of literature shows that changes in rainfall and water endowments will have significant impacts on crop yield, crops' water requirements and income and welfare of farm families. The extent of the changes in yield depends on the crop type, assumptions related to the CO2 fertilization effect, climate scenarios and adaptation abilities. On adaptation, the government's efforts have been distinguished in the improving agricultural productivity and irrigation development based on current technology, developing new technologies and policy reforms. Farmers' adaptive responses have also been identified. Some conclusions and recommendations are offered to increase the adaptive capacity of farmers and reduce negative impacts of climate change. 相似文献
2.
北京地区的地下水为满足农业灌溉,保障粮食生产起到了至关重要的作用。但是随着开采的急剧增加,地下水位出现了连续下降的趋势。为掌握地下水水位对农业灌溉的响应,选取了主要受农业灌溉影响为主的一眼地下水监测井,通过对比地下水水位的日变化量与大气降水以及本地区冬小麦降水耦合度之间的关系,得出了地下水水位与冬小麦灌溉之间的关系。研究发现,冬小麦灌溉各个阶段,地下水水位相应下降,显示出两者之间存在密切关系。冬灌后至返青前,地下水得到了充分有效的补给,水位可以恢复到冬灌之前的水平;但是由于返青-拔节和灌浆期灌溉需水量较大而且降水量较少,地下水不能得到充分有效补给,静储量被消耗,地下水位持续下降。研究结果表明,如果在返青-拔节和灌浆期采用节水措施或者引用其他水源,减少地下水的开采量,可以达到采补平衡,实现地下水的持续利用。 相似文献
3.
Climate change has been documented as a major threat to current agricultural strategies. Progress in understanding the impact of climate change on crop yield is essential for agricultural climate adaptation, especially for the Huang-Huai-Hai Plain(3 H Plain) of China which is an area known to be vulnerable to global warming. In this study, the impacts of climate change on winter wheat(Triticum aestivum L.) yield between the baseline period(1981–2010) and two Representative Concentration Pathways(RCP8.5 and RCP4.5) were simulated for the short-term(2010–2039), the medium-term(2040–2069) and the long-term(2070–2099) in the 3 H Plain, by considering the relative contributions of changes in temperature, solar radiation and precipitation using the DSSAT-CERES-Wheat model. Results indicated that the maximum and minimum temperatures(TMAX and TMIN), solar radiation(SRAD), and precipitation(PREP) during the winter wheat season increased under these two RCPs. Yield analysis found that wheat yield increased with the increase in SRAD, PREP and CO2 concentration, but decreased with an increase in temperature. Increasing precipitation contributes the most to the total impact, increasing wheat yield by 9.53, 6.62 and 23.73% for the three terms of future climate under RCP4.5 scenario, and 11.74, 16.38 and 27.78% for the three terms of future climate under RCP8.5 scenario. However, as increases in temperature bring higher evapotranspiration, which further aggravated water deficits, the supposed negative effect of increasing thermal resources decreased wheat yield by 1.92, 4.08 and 5.24% for the three terms of future climate under RCP4.5 scenario, and 3.64, 5.87 and 5.81% for the three terms of future climate under RCP8.5 scenario with clearly larger decreases in RCP8.5. Counterintuitively, the impacts in southern sub-regions were positive, but they were all negative in the remaining sub-regions. Our analysis demonstrated that in the 3 H Plain, which is a part of the mid-high latitude region, the effects of increasing thermal resources were counteracted by the aggravated water deficits caused by the increase in temperature. 相似文献
4.
《Computers and Electronics in Agriculture》2009,65(2):262-267
Plant canopy temperature is used in many studies of plant/environment interactions and non-contact measurement is often made with radiometric surface thermometers commonly referred to as infrared thermometers. Industrial-quality infrared thermocouples are widely available and often used in agricultural research. While research on canopy temperature has provided management tools for production agriculture, the high cost of the industrial-quality infrared thermocouples has limited their adoption and use in production agriculture settings. Our objective was to evaluate a low-cost consumer-quality infrared thermocouple as a component of a wireless thermal monitoring system designed for use in a production agriculture setting. The performances of industrial-quality and low-cost consumer-quality sensors were compared under controlled constant temperature and under field conditions using both grass and cotton canopies. Results demonstrate that under controlled constant-temperature the two types of infrared thermocouples were “significantly the same” at 10 °C, 20 °C and 30 °C and “significantly not the same” at 40 °C and 50 °C. Across the temperature range tested, the consumer-quality infrared thermocouples temperature reading was closer to the thermocouple reading than the industrial-quality infrared thermocouples. A field comparison of industrial-quality and consumer-quality infrared thermocouple sensors monitoring a grass canopy and a cotton canopy indicated that the two types of sensors were similar over a 13–35 °C range. The measurement of temperature made with two types of sensors would not differ significantly. Based on these results we conclude that the lower-cost consumer-quality infrared thermometers are suitable for use in production agricultural applications. 相似文献
5.
河套灌区春小麦生产水足迹影响因子敏感性及贡献率分析 总被引：1，自引：0，他引：1
【目的】农业水资源高效利用是保障国家粮食和水资源安全的重要途径,作物用水评价是农业用水管理的主要研究课题之一。水足迹为农业用水评价提供了新的指标体系,对作物生产水足迹影响因素进行定量评价有助于进行水足迹调控,实现农业水资源高效利用。【方法】以河套灌区为研究区域,基于水足迹概念体系,利用改进的水足迹量化方法对河套灌区春小麦生产水足迹进行量化并分析其在研究时段内的演变特征;利用单因素轮换（One-At-A-Time,OAT）敏感性分析方法和贡献率分析方法探究气候、农业生产投入因子和水资源利用效率对春小麦生产水足迹变化的驱动力。【结果】春小麦生产水足迹在研究时段内呈显著下降趋势,从1981年的4.71 m3·kg-1,下降到2010年的1.52 m3·kg-1;同时年际变化呈现出较为明显的阶段性特征,可划分为波动性下降期（1981-1987年）、快速下降期（1988-1995年）、缓慢下降期（1996-2010年）,该变化规律与灌区农业生产和灌溉水平的发展特征基本一致;从水足迹的蓝、绿水构成来看,河套灌区春小麦生产水足迹中蓝水足迹比例超过90%,而绿水足迹比例不足10%,这与灌区农业生产用水特征相一致。敏感性分析显示,水足迹对各个因子的敏感性差别十分显著,日照时数、相对湿度、降水量、灌溉水利用系数和单位面积化肥用量在±20%波动的情况下,春小麦生产水足迹的波动范围分别为±30%、±24%、±2%、±63%和±4%,春小麦生产水足迹对灌溉水利用系数、日照时数和相对湿度的敏感性较高,对其余影响因子的敏感性较低。贡献率分析显示,研究时段内相对湿度的减少和降水量的增加促使春小麦生产水足迹的增加。而日照时数的下降、化肥使用量以及灌区用水效率的提高促使了春小麦生产水足迹的降低。定量分析结果显示,化肥和灌溉水利用系数对春小麦生产水足迹变化的贡献率分别为-36.89%和-39.42%,而气候因子的综合贡献率仅为2.80%,对研究时段内春小麦生产水足迹下降贡献率最大的是灌溉水利用系数,其次为单位面积化肥用量,而相对湿度、日照时数和降水量三者的贡献率相近,贡献率最小的是日照时数,这主要是因为日照时数在研究时段内的变率较小。【结论】气候、农业生产资料投入和水资源利用效率是影响作物生产水足迹的主要因素,就河套灌区而言,农业生产资料投入和水资源利用效率的提高是促使灌区春小麦生产水足迹下降的主要因素,而气候因子在研究时段内对春小麦生产水足迹的影响较小。该研究结果可为水足迹调控提供理论依据与实践参考。 相似文献
6.
湿地生态系统是地球上最丰富的生态系统之一,具有丰富的生物多样性,为工业、农业、能源、医疗业等提供大量生产原料,同时又能贮藏水源、调节洪水、补给地下水、净化水质,对人类具有巨大的环境和社会价值。近年来,人类活动造成的气候变化越来越明显,湿地生态环境又非常脆弱,极易受气候变化影响,尤其是温度升高和降水量减少,都会对湿地的生态环境产生重大影响,从而导致生物多样性减少、湿地退化甚至消失。本文从多方面论述了气候变化对湿地生态环境及生物多样性的影响,为湿地保护和利用提供参考。 相似文献
7.
8.
Remotely sensed imagery is currently used as an efficient tool for agricultural management and monitoring. In addition, the use of remotely sensed imagery in Europe has been extended towards determination of the areas potentially eligible for the farmer subsidies under the Common Agricultural Policy (CAP), through interactive or automatic land cover identification. For accurate quantification and fast identification of agricultural land cover areas from the imagery, a hybrid method, which combines automated clustering of self-organizing maps with object based image analysis, and called SOM + OBIA, is proposed. Performance analysis on three test zones (using multi-temporal Rapideye imagery) indicates that for the basic land cover categories (forest, water, vegetated areas, bare areas and sealed surfaces), unsupervised classification with the proposed SOM + OBIA method achieves an identification accuracy comparable to the accuracy of the traditional interactive object oriented analysis, with considerably less user interaction. 相似文献
9.
为了分析内蒙古自治区兴和县地下水开采引发的地质环境问题,采用实地调查和访问的方法,调查该地区农灌区、第四系含水层分布区和地下水位、水质历年变化情况。结果表明:农灌区地下水位大幅下降,浅层第四系含水层局部地区出现了疏干。针对调查结果,提出今后应当充分利用地表水资源并采取节水措施,节约地下水资源,以达到降低灌溉定额及减缓地下水水位下降趋势的目标。 相似文献
10.
It is widely accepted that pest infestations elicit a change in plant physiology, which cause detectable changes in crop leaf reflectance. In this study, we test the hypothesis that crop leaf reflectance may also be used to forecast the risk of pest infestation before they actually occur. We collected reflectance data in 160 spectral bands from 405 to 907 nm from excised leaf pieces from field grown maize plants under 3 irrigation regimes. Leaf material was collected at weekly intervals in two growing seasons. The same leaf pieces were used in choice bioassays with carmine spider mites to assess attractiveness to mites (spider mite “bio-response”) across irrigation regimes. In one growing season, we also obtained nutritional element data (lipid, protein, soluble sugar, starch, lignin, Ca, P, Mg, K, S, and Cl) from whole maize plants. Principal component analysis showed that potassium content (K) was highly negatively correlated with spider mite bio-response. Relative reflectance at 740 nm showed a highly significant and positive trend across spider mite bio-response classes, and that potassium content showed a highly significant and negative trend across the same classes. Thus, we argue that relative reflectance at 740 nm may be used to predict both potassium content and risk of spider mite infestation. Based on extensive reviews, potassium leaf content is known to reduce susceptibility of crops to pests. The results presented provide encouraging support for remotely sensed risk assessment of pest infestations through reflectance-based monitoring of maize leaf attractiveness and highlight that reflectance based monitoring of crop susceptibility may be possible through careful management of macro element crop properties, such as potassium content. 相似文献
11.
基于河南省314家麦农和30个基层政府部门55名工作人员的实地调研数据,对农户和政府的气候变化认知与适应措施进行比较研究。结果显示,麦农和基层政府对气候变化及其对农业生产的影响具有较高的认知度。其中,对于气候系统的变化,麦农的认知度高于基层政府;对于气候变化的具体表现和气候变化对农业生产的影响,麦农的认知度低于基层政府。研究还发现,麦农和基层政府对气候变化适应措施的选择偏好不同。超过80%的小麦种植户采取了气候变化适应措施,但主要是增加农药化肥投入和增加灌溉等被动性适应措施,基层政府倾向选择营造农田防护林和推广农作物新品种等主动性适应措施。对于气候变化适应的政策支持,加强气候变化相关的教育和培训、推荐农作物新品种、暴雨和干旱预警是麦农和基层政府的共同选择。 相似文献
12.
Global climate warming has been exerting impacts on agricultural pests. Pests also take some strategies to adapt to climate change. Understanding such adaptation could benefit more accurate predictions and integrated management of pest. However, adaptation to climate change has not been widely investigated in agricultural pests but has been well documented in model species, Drosophila, and reviewed by Hoffmann before 2003. To provide recent progress and references for agricultural entomologists who interested in thermal biology, here we have reviewed literatures since 2003 about adaptation to temperature changes under climate change. We mainly summarized thermal adaptation of Drosophila (especially to high temperatures) from three aspects, behaviors, plastic responses and micro-evolution and discussed how Drosophila increases their heat tolerance through these three mechanisms. Finally, we summarized the measures of thermotolerance and concluded the main progress in recent decade about the behavioral thermoregulation, mortality risks driven by limited evolutionary and plastic response under climate change, geographic distribution based on basal rather than plastic thermotolerance. We propose future work focus on better understanding adaptation of organisms including agricultural pests to climate change. 相似文献
13.
农业用水直接影响粮食安全生产,通过分析2000-2014年重庆市秦巴山区农业用水变化趋势及农业用水结构,并对影响农业用水变化的相关指标进行主成分分析,找出主导因素.分析结果表明,重庆秦巴山区农业用水量呈逐年上升趋势并趋于平稳,近几年维持在4.6亿m3左右,但农业用水量占总用水量的比例却有所下降,从2000年的55.1%下降到2014年的43.7%;农田灌溉用水占农业用水量的比例逐渐减小,农林牧渔业比例趋向合理,农业用水结构在向合理的方向发展;经济作物种植、农作物结构调整、养殖业发展、人口增长、灌溉面积和气候条件是影响重庆秦巴山区农业用水量变化的主要原因,其中气候因素影响未达到显著水平.具体分析发现,近15年重庆秦巴山区农业用水量增加主要是由于水果和蔬菜种植面积增长、养殖业发展、人口需求增长、有效灌溉面积增加引起的,同时,近几年农业用水量逐渐趋于平稳且未来几年也不会出现大幅增长. 相似文献
14.
The use of Global Navigation Satellite Systems (GNSS) is common among agricultural users and enables the producer to optimize crop production within soil variant fields to provide better farming practices. Many agricultural navigation systems are dependent on real time GNSS navigation solutions to aid and control farm machinery. Direct Current (DC) and Alternating Current (AC) transmission lines overhead are often suspected to create interference with GNSS equipment preventing farmers from utilizing their GNSS supported equipment. This paper provides evidence that only non-impeding effects on the receiver or incoming signals, in the form of cycle slips, were measured or detected from either the overhead lines and/or their corresponding support towers. No effect on code measurements was detected. The latter effect is due to reflection or brief masking by the towers. Tests were conducted under a set of three transmission lines, two 500 kV DC lines and one 230 kV AC line. Several GNSS receivers and processing methods, including real time and post-processed data, are used to measure and process data to study the position accuracy, dilution of precision, number of satellites tracked, code and phase errors, location and number of carrier phase cycle slips, carrier-to-noise density and L1–L2 carrier divergence. One commercial Real Time Kinematic (RTK) survey system was also used to verify the 450 MHz data link was operational. 相似文献
15.
全球气候变化下中国农田土壤碳库未来变化 总被引：5，自引：0，他引：5
农田土壤碳库对缓解气候变化、保证粮食安全具有重要作用。日益加剧的气候变化对农田土壤有机碳库演变的潜在影响受到广泛关注。全球气候变化所带来的温度、降雨和大气二氧化碳（CO2）浓度的改变,会通过影响净初级生产力（NPP）、外源碳投入和有机碳分解速率等因素改变生态系统碳循环过程。另外,气候变化也会通过改变土地利用方式和种植制度等农业措施改变生态系统碳循环。综述国内外农田土壤碳库演变对气候变化影响的研究成果表明,到21世纪末,中国气温将会升高3.9-6.0℃,降水有望增加9%-11%。至2050年,气温和降水的变化会造成中国农田系统碳投入相比1980年降低2.3%-10%（小麦、玉米和水稻平均值）。相反,在综合考虑CO2浓度升高的协同作用后,2050年中国农田系统碳投入相比1990年前将会增加13%-22%（平均年增长率0.2%-0.4%）。模型预测显示,至2020、2050和2080年,中国旱地0-30 cm土层有机碳在CO2低排放情景下分别会损失2.7、6.0和 7.8 tC·hm-2,在CO2高排放情景下分别会损失2.9、6.8和8.2 tC·hm-2,大概占1980年农田土壤碳的4.5%、10.5%和12.7%。综合碳投入和排放对农田土壤碳库的整体影响来看,21世纪末期中国农田土壤有机碳库含量较1980年会下降10%左右,但如果采取相应的管理措施,可有效抑制农田土壤碳库的降低甚至提高,如农田系统碳投入以每年1%的速度增加时,土壤碳库会在21世纪末增加两倍。目前的研究结果显示,气候变化是否会强烈影响农田土壤碳库依然有很大的不确定因素,其对固碳效应正面和负面影响相互抵消后成为碳源还是碳汇说法不一。因此,在采取缓解气候变化、增加农田土壤固碳的措施的同时,还需加强农田土壤碳库未来变化趋势的研究和探索,为中国政策框架的决定以及未来气候变化谈判提供可靠的科学依据。 相似文献
16.
17.
Effect of irrigation management on soil salinization in Manas River Valley, Xinjiang, China 总被引：2，自引：0，他引：2
Abstract The irrigated area of Manas River Valley in Northwest China is an example of the successful reclamation of massive
land affected by shallow ground water levels and salinization. To determine the effect of irrigation management practices
on soil salinization, soil profiles representing various soil types were sampled. The historical records on the characteristics
of irrigation management practices, groundwater level and soil salts accumulation in this region at four key periods, namely:
flood irrigation without drainage; flood irrigation with drainage but of low efficiency; irrigation in combination with lined
irrigation canals and exploitation of groundwater; and irrigation with the application of water-saving irrigation techniques,
were analyzed emphatically. In addition, the salinization status of cultivated land in 2010 and 2020 was also predicted by
using analogism according to the relationship between soil salinization and irrigation practices. The results revealed that
the application of the traditional irrigation methods, such as flood irrigation and ridge irrigation, resulted in a rapid
rising of groundwater level and salts accumulation in soil surface layers. However, with the way of well irrigation and well
drainage, the groundwater level and the desalinization in soil layers apparently lowered, leading to a substantial increase
of crop yield. Currently, the application of drip irrigation under mulch decreased the salts concentration in soil layers
and increased the crop yield. With the continuous application of drip irrigation, the average soil desalinization efficiency
in soil layers may increase. It is predicted that the percentage of salinized land would be reduced to 35%–40% when irrigation
water is utilized reasonably in 2010. With the high efficient utilization of irrigation water after 2020, the salinized land
would remain below 30%. It is concluded that with the improvement of irrigation management, an obvious desalinization would
appear in the soil surface layers and the area of salinized land in this study area would gradually narrow, but the land salinization
problem would be hard to totally solve.
__________
Translated from Journal of China Agricultural University, 2007, 12(1): 22–26 [译自: 中国农业大学学报] 相似文献
18.
《Computers and Electronics in Agriculture》2007,56(2):161-173
In order to investigate and understand drift from field sprayers, a steady state computational fluid dynamics (CFD) model was developed. The model was developed in 3D in order to increase the understanding of the causes of drift: a deviation in the wind direction cannot be captured by a 2D approach, the wake behind a wind screen is not symmetrical, the effects of a changed nozzle orientation may not be symmetrical. The model's accuracy was validated with field experiments carried out according to the international standard ISO 22866. A field sprayer with a spray boom width of 27 m and 54 nozzles (Hardi ISO F110-03 at 3 bar) was driving at 2.22 m/s over a flat pasture. During the experiments the wind direction was perpendicular to the tractor track. The model explained the variation in drift replicates during each single field experiment through varying boom height (0.3–0.7 m), wind velocity (1.3–2.5 m/s), wind deviation (−18° to +18°) from the direction perpendicular to the tractor track and injection velocity of the droplets (17–27 m/s). Boom movements had the highest impact on the variations in drift values (deviations in drift deposits of 25%), followed by variation in wind velocity (deviations in drift deposits of 3%) and injection velocity of the droplets (deviations in drift deposits of 2.5%). Wind deviation from the direction perpendicular to the tractor track had a reducing effect on the drift values (deviations in drift deposits of 2%). Small variations in driving speed had little influence on drift values. Near drift (<5 m) is predicted well by the model but the increased complexity compromised the predictions at greater distances. The model will be further developed in order to improve far drift prediction. Dynamic simulations will be performed and the model for turbulent dispersion will be optimized. The model did not require calibration. 相似文献
19.
南疆气候干旱,降水较少且分布不均匀,水资源极其紧缺,农业用水仍以传统的灌溉方式为主,水资源浪费严重,设备节水化、智能化等程度较低。为了解决当前灌溉上存在的问题,基于物联网技术、软件开发技术、自控技术设计了一套适用于南疆小麦的智能灌溉系统。该系统通过Java语言编写的远程管理平台实现对小麦田块中电磁阀、水泵远程控制;数据采集模块采集土壤温湿度信息传输至中央处理器;中央处理模块根据采集信息结合数据库分析决策小麦实际需水量;控制模块通过变频器调节水泵转速来保证恒压灌溉。此系统对实现小麦的精准灌溉、合理利用水资源及提高农作物产量具有重要意义。 相似文献
20.
This paper describes the design and testing of an airborne multispectral digital imaging system for remote sensing applications. The system consists of four high resolution charge coupled device (CCD) digital cameras and a ruggedized PC equipped with a frame grabber and image acquisition software. The cameras are sensitive in the 400 to 1000 nm spectral range and provide 2048 × 2048 active pixels with 12-bit data depth. A 24 mm lens is attached to each camera via an F to C mount adapter, resulting in an imaging size of 0.63 times the flight altitude. The four cameras are equipped with blue (430–470 nm), green (530–570 nm), red (630–670 nm), and near-infrared (NIR) (810–850 nm) bandpass interference filters, respectively, but have the flexibility to change filters for desired wavelengths and bandwidths. The cameras are arranged in a quad configuration and attached to adjustable mounts that facilitate aligning the cameras horizontally, vertically, and rotationally. The image acquisition software allows the synchronized black-and-white band images from the cameras to be viewed on the computer monitor in any one of the four modes: a quad, one band image at a time, a normal color composite, or a color-infrared (CIR) composite. The band images are refreshed continuously to allow the operator to selectively save images with correct areas of interest. The selected four-band composite image is saved as a tiff file and consecutive images can be saved in 1-s intervals. A band-to-band alignment procedure based on the first- and second-order polynomial transformations was presented to further align the four band images. The system performed well in both stationary and airborne testing conditions. Airborne images obtained from agricultural fields, rangelands, and waterways demonstrate that this system has potential for monitoring crop pest conditions, mapping invasive weeds and assessing natural resources. 相似文献