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1.
A field trial was carried out during 1993–94 and 1994–95 winter seasons on Udic Ustochrept to evaluate the performance of dryland barley under varying profile moisture status and nitrogen levels. Three levels of initial moisture status of the root zone profile were: wet (100% field capacity), moderately wet (50% field capacity) and dry (rainfed) as the main treatment. The sub treatments were 0, 40, 60 and 80 kg N ha?1. During 15 to 60 days after sowing (DAS) availability of soil nitrogen and its uptake by the crop attained the highest values under wet regime. However, at 105 and 130 DAS dry moisture regime resulted in maximum values of both available soil nitrogen and plant nitrogen contents. In the same tune biomass production attained the higher values under wet regime as compared to the dry regime during 15 to 60 DAS and the trend was reverse at 105 DAS. Grain yield attained the highest value under dry regime followed by wet and moderately wet regimes. Irrespective of the profile moisture status both productivity and nitrogen use efficiency enhanced with the increase in nitrogen doses from 0 to 80 kg ha?1. Role of nitrogen was more pronounced under wet regime.  相似文献   

2.
晋江流域非点源氮磷负荷及污染源解析   总被引:8,自引:0,他引:8  
计算流域非点源氮磷负荷并以此开展源解析对于水体污染控制具有重要意义。基于DEM数据,运用GIS工具划分子流域,提取土地利用和土壤类型等空间相关资料,通过调查及小区试验获取模型参数,建立晋江流域非点源氮磷污染负荷模型;利用SLURP模型和输出系数模型分别核算流域内不同景观类型土地输出径流和农村污染溶解态氮磷负荷,利用修正的USLE土壤侵蚀通用方程核算吸附态氮磷负荷,并进行污染源解析。结果表明:晋江流域非点源氮负荷为12298.95t/a,大部分为溶解态氮,占到了94.13%,主要来自畜禽养殖、农田径流和农村生活污水,其源贡献率分别为31.72%、26.38%和17.44%;非点源磷负荷为667.04t/a,溶解态磷和吸附态磷对流域总磷负荷贡献比例相当,分别为56.73%和43.27%,主要来自土壤侵蚀、农田径流和农村生活污水,其贡献率分别为43.27%、21.10%和12.25%。总体分析表明,土壤侵蚀、农田径流和畜禽养殖是影响晋江流域非点源氮磷负荷的主要污染源,亟待优先控制。  相似文献   

3.
为探明黄河流域不同土地利用方式下地表径流中COD和TN污染分布规律,以安家沟流域为研究对象,采用平均浓度模型,对径流来源及其污染负荷进行了分析研究。结果表明:安家沟流域不同土地利用方式下地表径流中7项污染物质量浓度平均超标1.31倍,其中ρ(COD_(Mn))和ρ(TN)分别超标1.78,2.11倍;劣Ⅴ类水质出现的平均频率为23.86%,其中COD_(Mn)和TN平均出现频率分别为28.17%,52.03%;不同土地利用措施受径流量及其拦蓄效率和污染物输出水平的影响,COD_(Mn)和TN两者污染负荷总量主要分布在林地和农地,其单位面积污染负荷以荒坡为最大(2.989kg/hm~2),草地次之(2.937kg/hm~2),林地第三(1.327kg/hm~2),农地最小(0.447kg/hm~2);在坡面到沟道的径流过程中,由于土壤入渗等因子的影响,污染物总量在流域径流过程中具有明显的衰减过程,ρ(COD_(Mn))衰减了40.01%,ρ(TN)衰减了38.33%。研究显示,安家沟流域COD和TN污染在不同土地利用措施之间分异明显,合理规划土地利用方式、加强水土保持措施可有效减轻面源污染的发生。  相似文献   

4.
澄江尖山河小流域不同土地利用类型面源污染输出特征   总被引:11,自引:3,他引:11  
研究了自然降雨条件下澄江尖山河小流域4种不同土地利用类型径流小区中面源污染输出特征。结果表明,不同土地利用类型径流小区中面源污染物输出量不同,农地的全磷输出量最大,其次是人工林,次生林和灌草丛较小;氨氮和COD输出量表现出农地和人工林大于次生林和灌草丛。不同土地利用类型径流中面源污染物输出浓度没有显著差异,但从总体上来看,植被覆盖度越高,径流水中的氮、磷浓度越高,而COD、氨氮浓度越低,硝态氮浓度是亚硝态氮浓度的8.5~111倍,可溶态氮以硝态氮形式流失为主;侵蚀泥沙有富集养分的特征,且次生林和灌草丛的富集率高于农地。不同土地利用类型侵蚀泥沙中全氮和全磷的输出量依次为:农地>人工林>灌草丛>次生林,速效氮和速效磷则为:农地>人工林>次生林>灌草丛。与氮相比,表层土壤中的磷更容易随径流流失,磷的输出以泥沙结合态为主,特别是速效磷。  相似文献   

5.
土地利用和农业管理对丹江流域非点源氮污染的影响   总被引:3,自引:0,他引:3  
为研究土地利用和农业管理对流域非点源氮污染的影响,选择南水北调中线的重要水源地丹江流域作为研究区,应用SWAT模型模拟了流域地表水硝酸盐氮和氨氮负荷,揭示了土地利用变化和不同施肥灌溉措施对氮污染负荷的贡献。结果表明:(1)流域内全年氮污染分布不均,硝酸盐氮和氨氮污染较为严重的时段集中在每年7—9月,输出量分别为734.32,735.36 t,占全年硝酸盐氮和氨氮输出量的50%以上;(2)硝酸盐氮和氨氮的输出量具有较大的空间差异,自上游至下游逐渐加重,污染较为严重的子流域主要集中在丹凤县和商南县;(3)通过设置情景模拟,当坡度大于15°和25°的耕地退耕还林时,流域硝酸盐氮负荷分别减少59.83%和45.89%,氨氮负荷分别减少48.91%和35.78%。当流域内施肥量和灌溉量分别降低20%时,流域硝酸盐氮负荷分别减少3.63%和13.26%,氨氮负荷分别减少0.12%和15.65%;(4)耕地是流域氮污染的主要来源,降低流域施肥灌溉量和陡坡地退耕还林是控制流域非点源氮污染的关键。  相似文献   

6.
Soil salinization and non-point source pollution are among the most important and widespread environmental problems in European Mediterranean regions. Sweet sorghum (Sorghum bicolor (L.) Moench var. saccharatum) is a moderate to high salinity tolerant crop with low water and nutrient needs, seen as an alternative to grow in the water scarce regions. A three-year multifactorial study was conducted in southern Portugal to evaluate the combined effects of saline water and nitrogen application on the dry biomass (total, stems, and leaves), sugar content (total reducing sugars and sucrose contents), and sugar yield (here defined as the product of total reducing sugars and stems dry biomass) functions of sweet sorghum. Sorghum dry biomass and sugar yield showed diminishing returns for each incremental change of nitrogen. The use of saline irrigation waters also led to yield reduction. Exception was sucrose content which increased with increasing levels of sodium in the soil. Nitrogen need decreased as the amount of sodium applied increased. Stem dry biomass, sucrose content, and sugar yield progressively increased with progress in the experiment. The effect could be attributed to the increase of the amount of irrigation applied throughout the years, thus increasing the leaching fraction which promoted salt leaching from the root zone, reduced the salinity stress, increased plant transpiration, nitrogen uptake and biomass yield.  相似文献   

7.
We evaluated the impact of nitrogen (N) cycling on N pollution of stream water, with emphasis on N disposed of (hereafter referred to as “disposal N”) from human and livestock excrement and the N surplus in cropland, compared to the total-N concentration of stream water, in seven zones of Asahikawa City characterized by various types of land use. In order to estimate N cycling, we used the Nitrogen Flow Model, composed of the N budgets of human, livestock, and cropland subsystems. The urban area with a population density of over 4,000 persons km-2 generated a very large amount of disposal N (about 2,700 kg N ha-1 cropland y-1). Based on the amount of disposal N and the volume of domestic sewage water used, the N concentration estimated for the urban area was 34 mg N L-1, which found in the effluent from the sewage treatment facility (24–28 mg N L-1), regardless of the season. Thus, it was indicated that most of the disposal N in the urban area was discharged directly to streams through the sewage treatment facilities, contributing to a point source of N pollution of stream water. In addition, the disposal N from livestock facilities was larger in pig and poultry farming areas than in other farming areas, contributing to some extent to a potential source of N pollution. As a result, the concentrations increased above 1 mg N L-1 in the urban and surrounding areas. On the other hand, the N surplus in cropland was practically determined by the N flows associated with chemical fertilizer, livestock excrement as manure, and crop uptake. The N surplus was similar among the seven zones, ranging from 69 to 99 kg N ha-1 y-1. The N concentration estimated from the amount of N surplus and 50% of mean annual precipitation as a discharge rate was 13.6–19.5 mg N L-1. Most of the surplus N was indicated to be leached out. However, the total-N concentration measured in the major streams flowing through Asahikawa City was mostly below 1 mg N L-1 except for the urban and surrounding areas. The surplus N in cropland may not reach the streams, even if N leaching occurs, probably due to N removal by plant uptake, denitrification, and sedimentation in the riparian zone and stream channels. Thus the effect of agricultural practices on N pollution of stream water was not appreciable.  相似文献   

8.
江川灌区旱田改水田加剧水体氮磷污染   总被引:1,自引:1,他引:1  
黑龙江省江川灌区实施旱田改水田后,粮食产量持续上升,同时也暴露了以总氮和总磷为主的非点源污染问题。该文在GIS平台的支持下,运用SWAT模型,建立了模型所需的空间数据库和属性数据库,并运用实测资料对模型参数进行了率定。最后,设置了不同的情景,在耕地面积不变的情况下,改变水田比例为现状的70%、50%,从而研究农业非点源污染输出变化。研究表明:水田面积为70%和50%的情况下,月平均径流深比现状减少20.95、41.37 mm,总氮负荷减少27.84、48.16 t/a,总磷负荷减少1.66、2.89 t/a,说明旱田改水田将会对水环境产生不利影响。通过情景模拟发现,减少施肥量和节水灌溉均可以在一定程度上控制污染物输出,施肥量减少50%后,总氮输出减少25.23%,总磷减少16.32%。在实际生产生活中,为保证粮食产量,可以通过改变施肥方式或设置人工湿地等方法减少农业面源污染。  相似文献   

9.
该文以季节性冻融灌区内蒙古河套灌区为研究对象,建立灌区冻融期地下水补排模型,与三维地下水数值模型相结合,构建适用于季节性冻融灌区的生育期-冻融期全周年地下水动态模拟模型。采用河套灌区2006—2013年灌区实测地下水埋深对模型进行了率定和验证,并针对河套灌区不同地下水矿化度可开采区(分别为2.0、2.5及3.0g/L)、不同渠井结合比设置了18种井渠结合节水情景,对其地下水动态进行了预测。结果表明,该文构建的冻融期模型能准确反映其地下水动态过程;井渠结合后地下水埋深变化与井渠结合区地下水开采利用的矿化度上限和渠井结合比有关,井渠结合区地下水矿化度上限越大,渠井结合比越小,地下水埋深增加越多;实施井渠结合后,灌区生育期平均地下水埋深增加0.103~0.445 m,秋浇期增加0.076~0.243 m,冻融期增加0.096~0.216 m;从空间上看,全灌区年均地下水埋深增加0.096~0.316 m,井渠结合区增加0.346~0.635 m,非井渠结合区变化较少,一般不足7 cm。该文为季节性冻融灌区开展大规模井渠结合灌溉提供参考。  相似文献   

10.
基于沙化状况和适宜性的土地利用结构调整   总被引:2,自引:2,他引:2  
根据科尔沁沙地2000年的土地利用数据、从相同时期的TM影像上提取的土地沙漠化数据和土地适宜性数据,运用ARC/INFO、ARCVIEW软件和Access统计软件,分析了研究区土地利用、土地沙漠化和适宜性之间的对应关系,基于土地利用现状和适宜性进行了土地利用结构的调整,确定调整土地的面积及其空间分布。主要结论如下:草地、耕地和林地是主要土地利用类型,沙漠化原因存在差异,耕地沙化的主要原因是不宜耕作的林地、草地的开垦,而林地和草地的沙化则是由于土地质量差、利用强度大而造成的。土地利用结构调整后,耕地面积减少,草地和林地面积增加。科尔沁沙地的治理应将土地利用结构调整与农业、畜牧业经营方式的改变、土壤改良结合起来。  相似文献   

11.
Abstract. Physical, chemical and environmental consequences of land use change from cultivated land to desert grassland and vice-versa were monitored in the middle reaches of the Heihe River basin, which is one of the largest inland basins of arid northwest China. Levels of N and P in soils and surface waters and soil organic carbon were measured. After the first 3–5 years of cultivation the N and P contents of various former grassland soils, including mountain-meadow and plains-meadow grasslands, decreased significantly. After some 13 years of cultivation, soil nutrient content in former mountain meadow grasslands gradually stabilized, whereas those of desertified grassland, where cultivation had simply been abandoned, showed a notable decrease. Under these latter conditions, soil N and P were lost at a rate of 276 kg ha−1 and 360 kg ha−1, respectively, over the 13-year period. The transformation of grassland into cultivated land and that of cultivated land into desert grassland resulted in organic carbon emissions of 1.68 Tg C and 0.55 Tg C, respectively, over 13 years. Land use changes in the arid inland region clearly have a significant influence on the soil organic carbon pool and carbon cycle. Falls in soil N and P led to 63% and 34% mean enrichment of N and P, respectively, in downstream waters, thus posing a future environmental problem for the arid region of northwest China.  相似文献   

12.
高潜水位采煤沉陷区土地损毁程度评价   总被引:1,自引:4,他引:1  
土地损毁程度评价是采煤沉陷区土地复垦方案编制和受损农民补偿标准制定的重要依据。该文以东滩煤矿为例,在系统梳理已有研究的基础上,构建评价指标体系,划分评价单元,采用基于模糊意见集中决策的序关系分析法(G1法)确定指标权重,针对高潜水位矿区的特点,将极限条件法和可拓评价方法相结合,对其2014—2018年开采造成的采煤沉陷区的土地损毁程度进行评价,结果表明:拟损毁的土地面积总共为1 675 hm~2,其中轻度损毁面积为968.2 hm~2,中度损毁面积为379.53 hm~2,重度损毁面积为327.27 hm~2。与简单的以积水状况确定损毁程度的经验方法比较表明,经验做法往往低估了高潜水位采煤沉陷区土地的损毁水平。该研究为东滩煤矿科学合理编制土地复垦方案、确定受损农民补偿标准提供了支持,为同类型的其他高潜水位采煤沉陷区土地损毁程度的评价提供了借鉴。  相似文献   

13.
土地利用的弹性规划研究   总被引:12,自引:2,他引:12  
市场经济越发达,经济生活中的不确定因素就越多。经济的不可预见性和难以预测性导致土地利用的变异性增加,从而对土地利用规划的弹性提出了要求。该文首次明确地界定了土地利用弹性规划的涵义;探讨了土地利用弹性规划的内容和研究方法。通过弹性比计算和弹性区间确定、评价目标和评价体系设计、以及柔性决策模型等方法对土地利用规划中的弹性预测、弹性评价、弹性决策以及弹性用地分区进行了探讨,结果表明:土地利用的弹性规划能较好地适应经济生活中不确定因素导致的用地数量、用地结构、用地方式等方面的变化。  相似文献   

14.
为了更合理地利用土地、减少面源污染,利用密云水库上游石匣坡地径流场不同土地利用试验小区的5年观测数据,分析不同土地利用方式对面源污染的影响。研究表明:不同土地利用方式多年平均次径流系数差异明显,依次为清耕休闲地>坡耕地玉米>荒草坡>鱼鳞坑刺槐>水平条山楂,多年平均土壤侵蚀量与径流中TP、TN和CODMn流失量随径流系数的增大而增加,流失量与径流系数呈显著的正相关关系;径流中养分含量与径流系数之间没有显著相关关系。因此,通过增加植被覆盖或改变土地利用方式可大大减轻水土流失及其造成的面源污染。  相似文献   

15.
中国东部精细农业中N肥施用的最新动态和建议   总被引:21,自引:0,他引:21  
The Taihu Region in eastern China is one of China‘s most intensive agricultural regions and also one of the economic ally most developed areas. High nitrogen balance surpluses in the summer rice-winter wheat double-cropping systems are leading to large-scMe non-point source pollution of aquifers. In an interdisciplinary approach, four-year (1995-1998) field trials were carried out in two representative areas (Jurong County and Wuxi City) of the Taihu Region. Five farmers‘ field sites were chosen in each of the 2 locations, with each site divided into “standard“ (farmers‘ practice) and “reduced“ (by 30%-40%) N fertilization. For both fertilization intensities, N balance surpluses and monetary returns from grain sales minus fertilizer expenditures were calculated in an economic assessment. Based on the field trials, the mineral N fertilizer application rates reduced by about 10% for rice and 20%-30% for wheat were recommended in 1999. Since 1999, the research focused on the trends in N fertilizer application rates and changes in grain and agricultural commodities prices. Summer rice N fertilizer use, in Wuxi City as of 2001, dropped by roughly 25%, while for winter wheat it decreased by 10%-20%, compared to the 1995-1998 period. This has been achieved not only by grain policy and price changes, but also by an increased environmental awareness from government officials. Nitrogen balance surpluses in Anzhen Town (of Wuxi City) have consequently diminished by 50%-75% in rice and by up to 40% in wheat, with reductions being achieved without concomitant decreases in physical grain yields or returns from sales minus fertilizer costs.  相似文献   

16.
可持续土地利用伦理探讨   总被引:5,自引:0,他引:5  
阐明了可持续土地利用伦理存在于“人 地”关系与“人 人”关系之中 ,是可持续土地利用的经济、法律和行政管理的重要补充措施之一 ,任何土地利用行为都要讲求生态、经济和社会效益 ,土地利用伦理追求三者整体效益的提高 ,促进土地资源可持续利用。土地利用伦理观可视为土地利用生态伦理、经济伦理和社会伦理的结合 ,其实现有赖于生态理念贯穿于各种社会经济活动中。  相似文献   

17.
基于SWAT模型的流域土地利用格局变化对面源污染的影响   总被引:6,自引:6,他引:6  
近年来随着流域经济社会的快速发展,密云水库流域的土地利用格局也发生了明显的改变,作为影响流域非点源污染输出的主要因素,探讨土地利用格局的演变对非点源污染的影响对有效控制非点源污染具有重要的意义。该文以密云水库上游流域为研究区,从土地利用变化与污染过程相互作用的角度出发,开展流域非点源污染过程对土地利用变化的响应研究。基于流域1995年、2000年、2005年3期的土地利用数据,基于SWAT(soil and water assessment tool)模型,模拟评价流域非点源污染负荷分布特征,并应用景观格局指数、典范对应分析(canonical correspondence analysis,CCA)和通径分析等方法,从全流域和三级保护区等多空间尺度,量化分析流域土地利用及其格局时空变化对非点源污染负荷的影响。研究结果表明流域的非点源负荷与土地利用格局间存在着密切的联系。格局指数能累积解释流域非点源污染负荷变化的56.3%。污染负荷受土地利用格局的破碎度和形状的影响较大。通径分析的结果表明,耕地、林地面积比例、形状指数和斑块密度是影响研究区非点源污染负荷输出的主要因子,其中形状指数和耕地面积比例对TN、TP负荷的解释能力要明显高于其他指标。从空间尺度上看,各格局因子与非点源污染负荷的关系具有尺度效应,随着空间尺度的递增,格局对负荷的解释程度降低,在较小的尺度范围内,尤其是一级保护区的解释能力最高,达到62.9%,表明离水库越近的区域应是非点源防治高度重视的区域。  相似文献   

18.
水土资源平衡是耕地合理开发与利用的前提,为定量评估粮食主产区水土资源平衡关系,促进耕地可持续利用,该研究提出以水定地的耕地配置模式,并以三江平原腹地的挠力河流域为研究区,在多源水土信息数据支持下,依据农田土壤水分平衡原理构建水土资源平衡模型,以评估水土资源平衡态势,进而揭示该流域耕地合理利用规模特征.结果表明:1)...  相似文献   

19.
通过对西苕溪流域不同用地类型的子流域出口设置监测点并进行定期水质监测,探讨该流域非点源氮污染特征及其区域性差异。不同月份的监测结果表明,总氮(TN)、溶解性总氮(DTN)、硝态氮(NO3--N)浓度在12月最高,7月次之,4月最低;铵态氮(NH4+-N)浓度在7月最高,12月次之,4月最低。典型子流域日监测数据表明:林地子流域水质监测点测得的氮明显低于耕地,降雨期林地子流域出口的氮浓度增加,耕地子流域降低,干旱期则相反。研究表明流域非点源氮污染主要受农业耕地用地类型的控制,降雨径流是西苕溪流域非点源氮输出的主要驱动因素,用地类型、不同形态氮的理化性质差异导致流域非点源氮呈现明显的季节、空间分布特征。  相似文献   

20.
农业土地利用系统氮足迹与灰水足迹综合评价   总被引:1,自引:2,他引:1  
氮足迹和灰水足迹作为定量分析人类活动对活性氮排放及水资源影响的指标,为农业土地利用系统环境效应评价提供了新的理论与途径。该文在氮足迹和灰水足迹理论的基础上,构建了县域尺度农业土地利用系统氮足迹与灰水足迹理论分析框架,以湖南桃江县为研究区,计算了农业土地利用系统氮足迹与灰水足迹。结果表明:1)1980-2010年氮足迹与灰水足迹、单位土地利用面积氮足迹与灰水足迹均呈逐年增加的趋势。2010年氮足迹和灰水足迹分别是1980年的2.02倍和2.36倍,单位土地利用面积氮足迹和灰水足迹分别是1980年的2.00倍和2.31倍;2)1980-2010年输入氮足迹和污染氮足迹分别增长了102.54%、128.79%。2010年肥料氮投入占输入氮足迹的72.72%,污染氮足迹占总氮足迹的32.79%;3)1980-2010年,每年氮肥灰水足迹均高于磷肥灰水足迹。活性氮流失的增长造成的稀释水量增加是农业土地利用系统灰水足迹增长的关键因素。评价结果显示,桃江县农业土地利用系统在足迹总量与单位土地利用足迹对大气和水资源的负面影响正在持续上升。氮足迹与灰水足迹综合评价方法能有效地识别区域农业土地利用过程对环境的负面效应,研究成果为降低农业土地利用过程的环境风险、制定农业土地利用系统优化方案提供参考。  相似文献   

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