土壤-水稻系统中重金属元素与其他元素之间的相互作用   总被引：3，自引：0，他引：3  

冯海艳杨忠芳  杨志斌 《地质通报》2007,26(11):1429-1434

通过相关关系的统计分析,探讨了四川省61件水稻籽实及其根系土中重金属元素与其他元素间的相互关系。研究结果表明:①水稻籽实对重金属元素、微量元素、大量元素的富集系数差异很大,元素富集系数之间具有显著的相关性;②水稻籽实中重金属元素的含量与土壤中部分元素的含量之间存在着显著的相关关系;③水稻籽实重金属元素的含量与籽实中其他元素含量之间的相关关系显著。结合元素之间的相互作用对元素地球化学行为的影响,评价了作物籽实中重金属元素的危害程度,为土壤修复提供了新思路。  相似文献   

福州市表层土壤农业生态环境质量评价   总被引：3，自引：0，他引：3       下载免费PDF全文

魏为兴 《中国地质》2007,34(2):354-358

本文用地球化学指标和分级聚类模型中的积分值法,选取了N、P、K2O等16个指标对福州市表层土壤的农业生态环境质量进行了初步的评价分类。共划分为5个级别农业生态环境区。其中一般生态环境区面积最大,占全部面积58%。优良与良好生态环境区所占面积相对较小,两者合计面积同极差生态环境区面积相当,约占3%。各环境区多数富钾元素,贫中量、微量元素。并根据各个生态环境区的特点,对福州市农业规划与布局提出了建议。  相似文献   

大气环流对中国稻飞虱危害的影响及其预测   总被引：1，自引：0，他引：1  

钱拴  霍治国 《气象学报》2007,65(6):994-1002

稻飞虱是中国和许多亚洲国家水稻生产上最重要的害虫。文中通过对上一年1月至当年8月74项大气环流特征量构建所有不同时段的组合,全面分析了大气环流特征量与中国稻飞虱发生面积率的相关关系。筛选出了影响中国稻飞虱发生面积率的关键环流特征因子52项,其对中国稻飞虱发生影响的重要次序为副热带高压类→极涡类→槽类→其他类;影响的时段主要为当年7—8月,其次为上年6月至当年6月。其中,副热带高压类、极涡类关键环流因子分别有35项和12项,占全部关键环流特征因子的67%和23%,在很大程度上决定着中国稻飞虱发生的面积。确定的直接影响中国稻飞虱发生的关键环流特征因子有11项,其中6项较好地表征了中国稻飞虱发生面积率轻、偏轻、偏重、重4个级别的气候特征。用直接影响中国气候的关键环流特征因子建立了当年3—9月的中国稻飞虱发生面积率月预测模式,每月初可以制作预报。该模式历史拟合效果较好,对2003年中国稻飞虱发生面积率的外延预报准确率分别达85.6%、90.5%、90.5%、90.4%、90.9%、93.2%、96.3%。同时,本研究还利用1—11月稻区月降水量、平均气温、日照时数所构建的所有不同时段的组合,分析了关键环流特征因子与稻区生态气象条件、中国稻飞虱发生面积率之间的关系。结果表明:三者之间相关密切,这种关系表现为大气环流通过影响稻区日照、气温和降水的变化导致稻飞虱发生条件的灾变,进而影响稻飞虱发生面积率。  相似文献   

Toward an Ecological Explanation of Agricultural Unemployment in Bangladesh     

Abu Muhammad Shajaat Ali 《The Professional geographer》1998,50(2):176-191

Cultural ecology theoretical framework was found suitable to explain unemployment in agriculture in three villages in Bangladesh. Path analysis and multiple regression statistics were used to examine the direct, indirect, and total effects of eight independent human, social, environmental, and technology variables as well as their aggregate contribution on agricultural unemployment. The multiple regression model explains 86.2% of the total variation in unemployment in agriculture; they were followed by environmental constraints and labor saving technology variables.  相似文献   

Mitigating Agricultural Emissions of Methane   总被引：7，自引：0，他引：7  

A.R. Mosier  J.M. Duxbury  J.R. Freney  O. Heinemeyer  K. Minami  D.E. Johnson 《Climatic change》1998,40(1):39-80

Agricultural crop and animal production systems are important sources and sinks for atmospheric methane (CH4). The major CH4 sources from this sector are ruminant animals, flooded rice fields, animal waste and biomass burning which total about one third of all global emissions. This paper discusses the factors that influence CH4 production and emission from these sources and the aerobic soil sink for atmospheric CH4 and assesses the magnitude of each source. Potential methods of mitigating CH4 emissions from the major sources could lead to improved crop and animal productivity. The global impact of using the mitigation options suggested could potentially decrease agricultural CH4 emissions by about 30%.  相似文献   

湖南农业抗旱能力综合评价   总被引：2，自引：0，他引：2  

刘迎春  肖谦益 《云南地理环境研究》2007,19(4):39-42,57

利用灰色系统理论中的关联分析建立了湖南农业抗旱能力评价的指标体系，运用密切值法对湖南14个地州市的抗旱能力进行了综合排序。其结果表明湖南省各州市的农业抗旱能力差异较大，其中：衡阳（0．03）、常德（0．32）密切值小，抗旱能力强，株洲（3．14）、张家界（3．34）密切值大，抗旱能力弱。并根据湖南的实际为其抗旱减灾、提高抗旱能力提出了合理的建议与对策。  相似文献   

The economic impact of climate change on Kenyan crop agriculture: A Ricardian approach   总被引：3，自引：2，他引：1  

Jane Kabubo-Mariara  Fredrick K. Karanja 《Global and Planetary Change》2007,57(3-4):319-330

This paper measures the economic impact of climate on crops in Kenya. We use cross-sectional data on climate, hydrological, soil and household level data for a sample of 816 households. We estimate a seasonal Ricardian model to assess the impact of climate on net crop revenue per acre. The results show that climate affects crop productivity. There is a non-linear relationship between temperature and revenue on one hand and between precipitation and revenue on the other. Estimated marginal impacts suggest that global warming is harmful for crop productivity. Predictions from global circulation models confirm that global warming will have a substantial impact on net crop revenue in Kenya. The results also show that the temperature component of global warming is much more important than precipitation. Findings call for monitoring of climate change and dissemination of information to farmers to encourage adaptations to climate change. Improved management and conservation of available water resources, water harvesting and recycling of wastewater could generate water for irrigation purposes especially in the arid and semi-arid areas.  相似文献   

Improving Indigenous Technologies for Sustainable Land Use in Northern Mountainous Areas of Vietnam     

LeQuocDoanh HaDinhTuan 《山地科学学报》2004,1(3):270-275

More than 30 ethnic groups are now living in northern mountainous regions, Vietnam, mainly relying on shifting cultivation with the fallow period being shortened from time to time. Naturally, soil fertility reduces from cycle to cycle, entailing the reduction of productivity. Large areas of moderately sloping lands suitable for upland agriculture have become bare after many cultivation-fallow cycles. The soils there have been severely degraded with more toxicity, low porosity, low water retention capacity and poor floral diversity. Normally, these lands cannot be used for food crop cultivation. So farmers in uplands have to rely on slash-and-burn practices for their livelihood. As there is no more forest with good soil in medium slopes, farmers go to cut forests in watershed, high slope lands and old forests up to the mountains‘ top. There are ecologically and environmentally very sensitive areas, so their destruction will inevitably cause hazardous consequences in the whole basin. Meanwhile,cultivation in these areas has low economic efficiency and sustainability because the crop yield may decrease very fast due to severe erosion as the higher the slope, the more serious erosion. Consequently living standards of highland farmers remain low and unstable. Sustainable farming on these lands in the perspective of a seriously deteriorated ecology and environmental is not an easy task. There have been many projects trying to help mountainous farmers get out of their vicious circle. However, due to different reasons, the results gained are low, and in some cases,things ceased to move after the projects phased out. During past few years, based on the farmer experiences, the Vietnam Agricultural Science Institute has cooperated with local and international partners to implement different projects in order to solve the problems by developing simple, easy and cheap cultivation technologies, which can be accepted and applied by local poor farmers for sustainable agricultural production. The first results of our activities offered good opportunities for sustain food production, improve soil health, recharge of aquifers,and enhanced household income for better rural lively hoods in the upland eco-regions of northern Vietnam.  相似文献   

关于直播水稻观测方法问题的探讨     

胡世明  胡珀 《气象科技》2015,43(4):750-753

根据湖北江夏国家农业气象观测一级站在最近几年水稻观测中实际遇到的情况以及调查发现,直播水稻已形成不推而广的迅猛发展趋势,作为农业气象观测已不可回避地会遇到直播水稻的生育进程观测问题。由于种植方式的改变,大田植株分布形式也发生了根本的变化,仅以传统的移栽水稻制定的现行《农业气象观测规范》已无法处理好直播水稻的观测问题。为此,笔者依据《农业气象观测规范》,结合实际观测经验,分析直播水稻与移栽水稻的差异以及由此引出的新问题,提出了新的观测处理方法,以供同行探讨。  相似文献   

基于FastICA算法和MODIS数据的水稻面积提取   总被引：1，自引：0，他引：1       下载免费PDF全文

耿利宁  景元书  杨沈斌  浩宇 《大气科学学报》2015,38(6):819-826

以苏、皖、赣三省为研究区域,采用FastICA算法从MODIS数据中提取2010年水稻种植面积,并验证该算法在混合像元分解中的有效性。在对2010年46景8 d合成地表反射率产品数据进行预处理的基础上,结合MODIS土地利用产品和平滑滤波算法,构建耕地类型像元的I_LSW和I_NDV时相变化曲线。依据I_LSW和I_NDV曲线在水稻移栽期前后的变化规律,并根据由各地区水稻I_NDV时相曲线计算得到水稻相似性指数,从MODIS影像中提取水稻像元。采用FastICA算法对潜在水稻像元水稻生长期内的I_NDV时相曲线进行分解,计算每个像元的水稻丰度,绘制水稻丰度图,获取研究区各省水稻分布和种植面积。利用统计年鉴数据和样方资料对FastICA算法提取的水稻面积进行了验证。结果显示:采用水稻相似性曲线有利于提高稻田识别效率,所获取的水稻分布与实际情况吻合;FastICA算法能够分解不同地区水稻I_NDV时相曲线;与统计资料比较,江苏、安徽、江西三省水稻面积的提取精度分别为86.4%、87.9%、51.5%。江西水稻面积提取误差主要出现在地形起伏较大的山区。  相似文献