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1.
Rice research for food security and sustainable agricultural development in Asia: Achievements and future challenges 总被引：1，自引：0，他引：1
Rice is the major staple food of Asia, and an important source of employment and income in rural areas, particularly in low-income countries. Research has contributed significantly in achieving food security by increasing the yield potential of rice in irrigated systems, reducing the crop maturity period and achieving yield stability by developing resistance against major insects and diseases in the modern high-yielding varieties. Poverty is, however, still extensive in fragile rainfed rice ecosystems where rice yield has remained low, as scientists have yet to develop high-yielding varieties resistant to abiotic stresses and problem soils. Rice production needs to be increased by another 70% over the next 30 years to meet growing food needs. This has to be achieved with less land, less water, and less labor to accommodate the demand for these inputs from the expanding nonagricultural sectors. The challenge to the rice research community is to make further shifts in yield potential of rice for the irrigated systems, to close the yield gaps in the rainfed systems through developing resistance of high yielding varieties to abiotic stresses, and greater understanding of the interactions between genotypes and environment, developing durable resistance against pests and diseases to reduce farmers' dependence on harmful agrochemicals, and to increase efficiency in the use of water, labor and fertilizers. As further intensification of rice cultivation is inevitable, scientists must understand the negative environmental side-effects of increasing rice productivity, to develop appropriate mitigation options. 相似文献
2.
K. Azizi S. Heidari 《International Journal of Environmental Science and Technology》2013,10(5):1019-1028
This study was conducted to determine how energy balances and economical indices of barley production are affected by irrigated and dry land farming systems. Data were collected from 26 irrigated and 68 dry land barley farms. The complimentary data were collected through questionnaires filled by farmers in face-to-face interviews during 2010. The results indicated that total energy input for irrigated barley was 19,308.96 MJ ha?1 and for dry land barley was 7,867.82. The non-renewable energy was about 66.83 and 71.02 % in irrigated and dry land systems while the renewable energy was 33.17 and 28.98 %, respectively. Energy use efficiency is energy output MJ ha?1 divided by energy input MJ ha?1. Energy use efficiency was 5.3 and 3.96 in dry land and irrigated systems, respectively. Although net return in the irrigated system (266.13$ ha?1) was greater than that in the dry land system (208.64) but the benefit to cost ratio in irrigated system (1.38) was lower than that in the dry land system (1.58). Results showed that human labor as well as machinery energy inputs were the most important inputs influencing the dry land and irrigated barley production systems, respectively. The second important input in the irrigated barley was electricity (with 0.16) which was followed by water for irrigation and diesel fuel (0.14 and 0.13, respectively). In total energy consumption, the ratio of non-renewable energy was greater than that of renewable energy. Since the main non-renewable energy input was diesel, electricity, and chemical fertilizers; therefore, management and improvement in the application of these inputs would increase the proportion of renewable energy. 相似文献
3.
The present study designed to monitor and predict land cover change (LCC) in addition to characterizing LCC and its dynamics over Al-Baha region, Kingdom of Saudi Arabia, by utilizing remote sensing and GIS-cellular automata model (Markov-CA). Moreover, to determine the effect of rainwater storage reservoirs as a driver to the expansion of irrigated cropland. Eight Landsat 5/7 TM/ETM images from 1975 to 2010 were analyzed and ultimately utilized in categorizing LC. The LC maps classified into four main classes: bare soil, sparsely vegetated, forest and shrub land, and irrigated cropland. The quantification of LCC for the analyzed categories showed that bare soil and sparsely vegetated was the largest classes throughout the study period, followed by forest, shrubland, and irrigated cropland. The processes of LCC in the study area were not constant, and varied from one class to another. There were two stages in bare soil change, an increase stage (1975–1995) and decline stage (1995–2010), and the construction of 25 rainwater-harvesting dams in the region was the turning point in bare soil change. The greatest increase was observed in irrigated cropland after 1995 in the expense of the other three categories as an effect of extensive rainwater harvesting practices. Losses were evident in forest and shrubland and sparsely vegetated land during the first stage (1975–1995) with 5.4 and 25.6 % of total area in 1995, while in 1975, they covered more than 13.8 and 32.7 % of total area. During the second stage (1995–2010), forest and shrubland witnessed a significant increase from 1569.17 km2 in 1975 to 1840.87 km2 in 2010. Irrigated cropland underwent the greatest growth (from 422.766 km2 in 1975 to 1819.931 km2 in 2010) during the entire study period, and this agriculture expansion reached its zenith in the 2000s. Markov-CA simulation in 2050 predicts a continuing upward trend in irrigated cropland and forest and shrubland areas, as well as a downward trend in bare soil and sparsely vegetated areas; the spatial distribution prediction indicates that irrigated cropland will expand around reservoirs and the mountain areas. The validation result showed that the model successfully identified the state of land cover in 2010 with 97 % agreement between the actual and projected cover. The output of this study would be useful for decision makers and LC/land use planners in Saudi Arabia and similar arid regions. 相似文献
4.
在长江和黄河源区的左冒西孔曲和纳通河、垮热洼尔玛河流域的不同植被覆盖下建立了天然径流观测场,利用观测天然降水和人工模拟降水,初步研究了江河源区不同植被覆盖下降水的产流产沙效应。结果表明,长江黄河源区的3个小流域内,在典型高寒草甸草地30°坡面上,退化较为严重的30%覆盖度以下的场地内,地表径流产出量明显大于覆盖度较好的95%、92%和68%场地,同时产沙量显著高于这3个场地,其平均单次降水形成的泥沙量是这三种盖度的2~4倍,由此造成地表侵蚀量平均为这3种盖度的3~10倍。通过对几次典型的降水形态的分析,在长江黄河源区高寒草甸草地的坡面上,不但降水量影响着产流产沙量,降水形态也影响着产流产沙量,降雨仍是引起水土流失的主要降水形态,在降水量相同的条件下,降雪可比降雨和雨加雪增加产流量2.1~3.5倍,可比降雨减少泥沙侵蚀45.4%~80.3%。人工模拟结果表明:对于覆盖度为5%和30%的强度退化草地,次降水量在3.5 mm时,就形成了较为明显的径流和产沙效应,当次降雨量达到7 mm,降雨持续时间15 min,5 m2场地内就会形成1 400 mL以上的径流量;在地表土壤含水量(FDR测0~5 cm平均含水量为36.7%)较高的情况下,次降雨量达4mm,降雨强度超过0.4 mm/min,在5 m2场地内历时5 min就能形成1 060 mL的地表径流,每100 mL径流中含泥沙高达1.6 g。这一试验结果在长江黄河源区3个不同的河源小流域是一致的。 相似文献
5.
区域化探资料在提高农作物产量上的应用成果 总被引：8，自引：9，他引：8
1991年,利用冀东地区已有1:20万区域化探资料,进行了在农业中的开发应用研究,在此基础上,选择区内微量营养元素和有益元素缺乏区,开展了增施微量元素Zn、Mn、Mo、B和Co肥料提高水稻、玉米、花生和苹果产量的应用研究。试验结果表明,增施微肥后,水稻、玉米、花生产量提高,平均增产10%以上,亩增收入平均40元以上,苹果增产30%以上,亩增收入大于1000元,增产效果和经济效益是明显的。这项成果如在整个冀东地区推广,其经济效益将是巨大的。 相似文献
6.
Lou Puli 《GeoJournal》1985,10(2):133-139
China's agriculture has much more urgent demand on irrigation and drainage than that of other countries'. At present, the country has a total irrigated area of 46 million hectares, accounting for 46% of the total cultivated land. This paper gives a brief introduction to the progress of the water resources development and a concise analysis on irrigation and drainage demands in various zones. Some salient experiences and lessons gained in these issues in the past some thirty years in China are reviewed. 相似文献
7.
依据云南省者竜—嘎洒地区土地质量地球化学调查数据,研究了表层土壤中Cr、Ni地球化学特征及主要影响因素,分析了农产品Cr、Ni含量特征。结果表明,研究区表层土壤中Cr、Ni含量受控于地质背景,光山—和平丫口岩体(σ)发育的土壤中Cr、Ni含量明显高于其他地层发育的土壤;不同类型土壤中Cr、Ni含量差异较大,且土地利用方式也会对土壤中Cr、Ni含量产生一定影响;研究区玉米、柑橘、茶叶、甘蔗、香蕉、核桃等农产品Cr、Ni含量均未超标,仅11件水稻Cr含量超过国家标准,占水稻样品总数的11.3%,区内农产品安全性总体较好;区内农用地(水田、旱地、园地、草地)面积为554.73km2,其中无风险(含量低于筛选值)面积为408.61km2,占比为73.66%,风险可控(含量在筛选值与管制值之间)面积为112.96km2,占比为20.36%,风险较高(含量>管制值)面积为33.16km2,占比为5.98%,土壤环境质量总体较好。针对部分土壤存在Cr、Ni污染风险问题,从水土保持、施肥方式、水旱轮作等角度提出了污染防控措施建议。 相似文献
8.
N. K. Sharma S. Bhardwaj P. K. Srivastava Y. J. Thanki P. K. Gadhia M. Gadhia 《International Journal of Environmental Science and Technology》2012,9(2):361-370
Irrigating food crops with treated wastewater is a popular management option in India. This study evaluated the impacts of land application of treated petrochemical effluent on soil chemical properties. Soil samples were collected from different depths from sites irrigated with petrochemical effluent for 2?years and from control sites. The effluent collected was analysed for different physic?Cchemical properties and its impact on Lagenaria siceraria (Bottle gourd) growth. 100% concentrated effluent was used for the study and compared with the control. It was observed that application of effluent significantly increased the major cations and anions in the field. On the basis of the study, it may be suggested that treated petrochemical effluent can be used as an alternate source for irrigating crops as it increases the nutrient content of the soil. The overall application indicates a lavishing growth of L. siceraria crop in petrochemical irrigated soil than control sites. This study provides information for better understanding of changes in soil properties due to land application of petrochemical effluent. These changes must be considered in developing possible criteria for preserving delicate ecosystems. 相似文献
9.
刁江流域上游的矿山和矿山开发引发了显著的土壤环境地球化学变化,突出表现是沿岸形成了严重的土壤重金属污染带。污染带的分布与近20多年来的洪水淹没区和引水灌溉区呈现高度的一致性。上游地带的土壤污染区有明显的尾砂沉积,污染呈显性状态,而下游地带的尾砂沉积现象不明显,污染表现为隐性。无论是上游还是下游,土壤中的As、Pb、Zn、Cd含量均异常高。水田的犁底层对污染物质具有明显的隔断作用,而旱地淀积层中的污染物含量比较高,对污染物质的隔断作用不明显。污染耕地上生产的玉米中的Cd、Pb、Zn含量和大米中的Cd、Pb含量超过国家食品卫生标准。 相似文献
10.
11.
人类引水、耗水构成了流域水循环系统中的一个子系统,即侧支循环系统。与此对应,主干循环则是大气降水形成径流、通过各级沟道和河道汇入干流、最后流入海洋的循环过程。以黄河流域实测资料为基础,对侧支循环与主干循环进行了研究。研究表明,从20世纪60年代末、70年代初以来,侧支循环相对强度指标和侧支循环绝对强度与主干循环绝对强度之比呈明显的增大趋势,而主干循环相对强度指标则表现出减小的趋势。以年系列资料为基础,建立了一系列多元回归方程,以表达侧支循环强度指标、主干循环强度指标和侧支循环绝对强度与主干循环绝对强度之比与影响因子之间的多元回归方程。结果表明,灌溉面积、年降水量、年均气温变化对黄河侧支循环相对强度指标变化的贡献率分别为86.55%,2.18%,11.25%;灌溉面积、年降水量、年均气温变化和水土保持面积变化对黄河主干循环相对强度指标变化的贡献率分别为57.61%,20.78%,11.03%,10.57%。 相似文献
12.
The Loess Plateau in Northwestern China, with 60 million inhabitants, is strongly endangered by heavy erosion quickly decreasing soil fertility and yield of crops, causing also severe problems in the main river of the area, uplifting its bed by strong sedimentation. This situation is mainly due to improper land use, cutting woods, ploughing up grasslands which are the consequence of the decreasing yield of former plough lands. This vicious cycle may only be disrupted by a proper land management based on the newest results of scientific research, on up to date data bases as well as on traditional methods. The land melioration methods must primarily aim at a prevention of further erosion and at an increase of infiltration by different methods, but all means of a proper country planning and development should be harmonised in order of halting of further deterioration of the area. 相似文献
13.
硒是重要的人体必需微量元素,对特色农业发展起着重要的助力作用。碧江区土壤硒元素含量平均值超过贵州省及全国硒含量均值。富硒耕地面积达29426 8万亩,具有较大的富硒资源开发潜力。成土母岩为炭质页岩所形成的土壤中硒元素含量高于其他类型成土母岩所形成的土壤,强酸性土壤中硒元素含量平均值高于其他酸碱度等级土壤,水田中硒元素含量平均值显著高于旱地、果园、水浇地等其他类型土地。成土母质是土壤中硒元素的主要来源及影响因素,pH值、有机质、土壤质地等理化条件对土壤硒元素有一定影响。 相似文献
14.
Yawar Hussain Sadia Fida Ullah Muhammad Babar Hussain Abdul Qayyum Aslam Gulraiz Akhter Hernan Martinez-Carvajal Martin Cárdenas-Soto 《Environmental Earth Sciences》2017,76(2):84
The area of Thal Doab is located in the Indus Basin and is underlain by a thick alluvial aquifer called the Thal Doab aquifer (TDA). The TDA is undergone intense hydrological stress owing to rapid population growth and excessive groundwater use for livestock and irrigated agricultural land uses. The potential impact of these land uses on groundwater quality was assessed using a DRASTIC model in a Geographic Information System environment. Seven DRASTIC thematic maps were developed at fixed scale and then combined into a groundwater vulnerability map. The resultant vulnerability index values were grouped into four zones as low, moderate, high and very high. The study has established that 76% of the land area that is underlain by the TDA has a high to very high vulnerability to groundwater contamination mainly because of a thin soil profile, a shallow water table and the presence of soils and sediments with high hydraulic conductivity values. In addition, only 2 and 22% of the total area lie in low and moderate vulnerability zones, respectively. The outcomes of this study can be used to improve the sustainability of the groundwater resource through proper land-use management. 相似文献
15.
南川市三泉镇岩溶区农田生态系统植被碳库的动态变化 总被引：3，自引：0，他引：3
通过农田样方观测与实验分析获得南川市三泉镇农田生态系统主要农作物的含碳率、经济系数、果实水分系数,结合该区近26年来( 1980- 2005)主要农作物产量与耕地面积的相关数据,用农作物产量与碳储量转换模型计算法估算和分析该区农田生态系统植被碳库的总量及构成的动态变化。结果发现: 近26年来该镇农田植被碳库和碳密度略有提高,具有微弱的碳汇效应。与邻近的四川盆地非岩溶区相比,该区农田植被碳密度较低。针对农田生态系统植被碳库的构成特点和动态特征,该镇今后应进行作物结构调整,适度增加水稻等大春作物的种植和马铃薯、油菜和饲料等小春作物的种植面积,稳定小麦等作物的播种面积; 加强农田基本建设,发展生态农业,以进一步提高农田生态系统植被碳库的碳储量和碳密度。 相似文献
16.
2001-2018年石羊河流域植被变化及其对流域管理的启示 总被引：1，自引：0，他引：1
植被是流域生态系统的重要指标,植被景观管理也是流域综合管理的重要内容。综合利用长时间序列MODIS反射率和归一化差值植被指数（NDVI）产品及Landsat卫星遥感影像,基于谷歌地球引擎（GEE）平台,利用计算机自动分类的方法,监测了2001-2018年间石羊河流域的植被（包括灌溉土地）的逐年变化,结合降水、径流量和地下水位地面监测数据,分析了全流域植被指数、植被面积、灌溉土地范围的变化特征及其与水循环之间的互馈关系。研究发现,2001-2018年间,石羊河流域的植被面积以每年约135 km2的速率增加,其中,自然植被和灌溉土地分别以每年60.5 km2和74.6 km2的速率增加。除了金昌区的植被增加以灌溉土地为主外,其他区域都以自然植被的增加为主。特别是民勤地区,由于十多年的持续调水和有效退耕,地下水位近年来开始抬升,自然植被开始恢复。但与此同时,中游凉州区和永昌县的生态风险加大。未来可从灌溉规模控制、地表与地下水统一调度、景观分级和配置技术发展、优化产业结构、强化与流域外的连通性等方面加强流域综合管理,提高流域社会系统弹性,增强可持续发展能力。 相似文献
17.
以赣南青塘—梅窖地区为典型区开展详细的调查研究工作,共采集了表层(0~20 cm)土壤样品889件,农作物样品72件。系统地分析了土壤及农作物中硒元素含量的空间分布特征及其与成土母质、土地利用类型和土壤理化性质的关系。结果表明：研究区土壤硒平均含量为044 mg·kg-1,其中面积比例为4859%的土壤硒含量处于足硒状态,面积比例为4286%的土壤硒含量处于富硒状态。在空间分布上,缺硒和潜在硒不足土壤仅呈零星分布。表层土壤硒含量在一定程度上继承了成土母质硒的含量,不同的土地利用类型土壤中硒含量也存在一定的差异。土壤有机质含量与硒含量呈显著正相关关系,与土壤pH值没有相关性。花生和水稻富硒率较高,其中花生和早稻含量均符合国家食品安全标准,仅晚稻存在一定的重金属超标现象。通过对比富硒土壤和不富硒土壤中晚稻重金属含量的超标率、硒的富集系数和含量,发现在富硒区晚稻中重金属的超标率远远低于非富硒区,说明土壤硒元素会在一定程度上降低晚稻中重金属元素的富集效应。 相似文献
18.
Mats Söderström 《Environmental Geology》1992,20(2):85-92
Spatial distribution of the salinity in groundwater used for irrigation and irrigated soil was investigated on Gammouda Plain, an important agricultural area in central Tunisia. Samples from 188 wells and irrigated fields were obtained in November 1988. Groundwater salinity ranges from 2 to 30 dS/m, and 50 percent of the sampled wells have a salinity higher than 3.5 dS/m. In most cases the soil samples have a salinity higher than 4 dS/m. Maps of salinity and leaching were produced by a geostatistical interpolation method based on ordinary kriging. In a great part of the plain, the estimated salinity levels indicate that there is a considerable risk for reduced yield potential for several of the most important crops grown. A rough estimation of the leaching fraction was computed from the soil and water salinity. Computer-based models of salinity ought to facilitate the general planning of irrigation management and crop selection. 相似文献
19.
This study investigated the changes of high temperature events during important growing period of rice (graining filling to maturity) of 2021-2050 due to climate change. Future climate scenarios were HadGEM2-ES simulation with RCP2.6 and RCP8.5 emission pathways. Relationship between high temperature and yield change was established from historical weather and field observations during 1981-2009 period. The impacts of high temperatures on China’s rice production up to 2050 were assessed by applying deduced regression models to climate scenarios. Key messages drawn from this exercise include: ①High temperature event exhibited gradual increase from 2021 to 2050 under both RCP2.6 and RCP8.5 scenarios, characterized by increased number of high temperature days (HSD), rising accumulated temperature with Tmax greater than 35 ℃ (HDD), and increased lasting days of high temperature (CHD). The HSD and HDD increased substantially in double rice cropping system of South China, single rice cropping system of Yangtze River Basin and rice area of Northeast China. ②High temperature hotspot was located near the border between Hunan and Hubei during 1961-2000, and might move towards northeast in the period of 2021-2050. ③Except the Northeast, China’s rice production suffered most from increased HDD during grain filling to maturity, indicated by significant negative and linear relationship between yield and HDD, whereas rice in Northeast China was subject to the increase of SDD during grain filling to maturity, with a significant and quadratic relationship between the yield and SDD. ④Compared to the high temperature risks during 1961-1990, climate change would increase the risks in majority of the rice area, especially in Hubei and Anhui-the central portion of Yangtze River Basin rice area, Guangdong, Guangxi and Hainan-south China double rice area, and south part of Northeast China single rice area. 相似文献
20.
江西赣南地区是典型的硒缺乏地理分布区,但近年来研究成果表明该地区稻谷富硒率高,土壤与稻谷富硒存在不一致的原因尚不明确,探讨土壤和稻谷硒含量特征和土壤硒的生物有效性,对赣南地区富硒土地资源利用和富硒农产品开发具有重要意义。本文以赣县清溪地区为研究对象,采用电感耦合等离子体质谱/发射光谱(ICP-MS/OES)等方法测定了研究区1734件表层土壤、57组稻谷及配套根系土硒等元素含量及硒形态地球化学指标;系统分析了区内土壤硒含量和分布特征、稻谷硒含量特征,探讨了根系土硒生物有效性的影响因素。结果表明:研究区表层土壤以足硒、富硒区为主,土壤硒含量与成土母岩关系密切,不同成土母岩区土壤硒含量规律为:古生代变质岩中生代花岗岩新元古代变质岩中生代陆源碎屑岩新生代第四系。根系土硒含量均未达到富硒土壤标准,稻谷富硒率为64.91%,稻谷对土壤硒的富集能力强(富集系数20.05%),当根系土硒含量≥0.25mg/kg时,水稻富硒率高达70.83%,能够稳定产出优质富硒水稻。硒的赋存形态是影响土壤硒生物有效性的主要因素,土壤总硒含量较低时,水溶态、离子可交换态、碳酸盐结合态硒的占比高,从而提升了硒的生物有效性;有机质含量低,对硒吸附能力弱,也是硒生物有效性高的重要原因。本研究认为,赣县清溪地区富硒、足硒土壤开发利用时,综合考虑土壤硒含量、土壤理化指标、硒形态对土壤硒生物有效性的影响,有利于科学指导天然富硒土地划定和富硒水稻产业开发。 相似文献