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1.
南方典型灌区农田地表径流氮磷流失特性 总被引：4，自引：0，他引：4
农田地表径流氮磷流失与土地利用、土壤和灌溉方式有着极为重要的联系,而且具有十分明显的地域特点。本文选取我国南方丘陵地区典型灌区——湖北省漳河灌区的水旱作物(分别为水稻和玉米)作为研究对象,开展了农田地表径流N素和P素流失特性及其影响因素的试验研究。结果表明:土地利用类型对地表N素流失量的影响显著,地表TN流失量表现为旱地>水田;土地利用类型对地表P素的流失量有较大影响,但差异性未达到显著水平,地表TP流失量表现为水田>旱地。随着降雨强度的增大,铵态氮和硝态氮浓度均呈减小的趋势,有机氮的比例由3.2%增至69.7%,无机氮比例由96.8%降至30.3%,更多的有机氮随地表径流流失;随着降雨强度的增大,农田排水总磷和磷酸磷也呈增加的趋势。采用节水灌溉方式,降雨利用率提高了14%~23%,节水率达15%,降雨排水量减少20~25 mm左右,能够有效降低农田氮、磷等养分流失对地表水的污染。作物生育期和地形地势差异也会影响降雨径流特征和农田养分流失。 相似文献
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3.
上海旱地农田氮磷随地表径流流失研究 总被引：14，自引：0，他引：14
选择上海宝山罗店镇具有代表性的旱地蔬菜农田生态系统，从2004年3月到8月的近半年时间里，通过对径流及径流中侵蚀泥沙的氮磷流失情况的连续监测，研究了旱地农田施肥与氮磷流失污染之间的关系，探讨了农田氮磷的迁移特征及环境效应，主要结果表明：当季施用化肥的地表径流总流失量，总氮为32．77kg/hm^2，总磷为8．1kg／hm^2，随径流排出农田的氮素中有37．7％是当季施用的氮素化肥，磷素中有26．9％是当季施用的磷素化肥；从过量施肥与环境污染之间的“因”与“果”来看，减量15％施肥区相比常规施肥区的茄子的产量减少2．7％，但是其污染负荷却减少了13．4％，表明在化肥利用的有效性上或增施化肥与控制环境污染之间，应该寻找一个最佳的平衡点。 相似文献
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西苕溪流域不同土地类型下氮元素输移过程 总被引：60，自引：3，他引：60
以西苕溪流域为研究对象,选择最有代表性的5种土地类型,模拟天然大暴雨,通过3次重复实验研究不同形态氮素随暴雨径流及径流沉积物的迁移过程,估算氮素在流域内不同土地利用/土地覆被条件下的损失率。研究结果表明,在相同的降雨条件下,氮素的流失速率和流失量随土地利用/土地覆被类型的不同表现出明显差异,地表径流水相总氮的流失量桑林最大,水田最小。水相不同形态的氮素流失量亦有所不同,悬浮颗粒态氮占地表径流水相总氮的70 %~90 %,水相溶解态氮的流失量以松林为最高,竹林、桑林和水田接近而且较低,不同类型的水相溶解态氮也随土地利用类型的不同表现出各自的特征。各土地类型单位面积、表层10 cm土壤氮素流失高达4.66~9.40 g·m-2,其中随径流沉积物相迁移的氮素占绝大部分(90 % 以上)。估算出的各土地利用类型总氮流失速率,地表径流水相为2.68~14.48 mg·m-2·min-1,径流沉积物相高达100.01~172.67 mg·m-2·min-1。 相似文献
6.
孟令尧 《地理与地理信息科学》2002,18(4):97-99,103
该文通过太行山几种土壤类型模拟降雨实验,研究其自然状态的土壤总氮、可溶态氮、总磷、可溶态磷的流失量及流失浓度。研究表明,自然状态土壤氮、磷流失初始浓度最高,随后呈缓慢降低趋势;总氮、总磷及可溶态磷浓度与土壤中氮磷含量有一定相关性,但受其它因素影响也较大;可溶态氮浓度与土壤中氮含量关系不大;各土壤累积产流量大小与土壤渗水性、表层结构及地表植被覆盖有很大关系,总氮、总磷累积流失量大小依次是棕壤土>石灰性褐土>褐土>淋溶褐土>酸性粗骨土。 相似文献
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野外观测试验于1997年在广东省鹤山茶叶科技研究所的赤红壤坡地上进行，试验设计了人工林下地表覆盖（A）、人工林下地表裸露（B）、等高梯田种植茶树（C）和等高梯田裸地对照（CK）4个处理，采用自制的径流收集器分别测定了各处理4场降雨的径流深度、径流系数、水土流失量和侵蚀量等指标，结果表明，CK的平均径流深度高产田3.72mm/10mm，降水流失率为37.2%，平均每10mm降雨的土壤侵蚀量为43.6kg.hm^-2，年土壤侵蚀模数为7.42t.hm^-2；其它3个不同植被覆盖处理的地表径流量比裸地对照降低2.20%-67.08%，平均土壤侵蚀量减少43.81%-90.83%；林下地表覆盖处理的保土效果果好，等高梯田种植茶树处理的保水效果最好。 相似文献
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三峡库区坡地生态工程控制土壤养分流失研究——以等高植物篱为例 总被引：46，自引：7，他引：39
三峡库区紫色土陡坡地径流小区大雨强模拟降雨实验表明,以等高植物篱为代表的坡地生态工程能相当有效地减少坡面侵蚀量、径流量和坡面氮、磷养分损失量。由于植物篱和带间覆盖稿秆对径流的阻滞作用使坡面径流与表土的混合、养分溶解交换过程更加充分,径流携带的养分流失成为有效养分流失的主要方式。通过施肥改善土壤渗透特性、抗蚀性及带间覆盖能明显提高控制坡面产沙、产流和养分流失。等高植物篱-农作系统各种处理中以施用有机肥和配施有、无机肥-带间麦秆覆盖两种处理效果最好。 相似文献
9.
灌溉和氮肥的施用是保障干旱荒漠区农田生产的关键措施,但过量的氮肥会随水分淋溶至深层土壤或地下水中,从而导致氮素的损耗和地下水的污染。本研究以黑河中游荒漠绿洲过渡带两种开垦年限的农田土壤(风沙土和灰棕漠土)为研究对象,通过土柱模拟试验监测分析了玉米生育期和休闲期内土壤水分和温度的动态变化及硝态氮(NO_(3)^(-)-N)的淋溶规律,揭示了不同耕作年限农田土壤中硝态氮损耗的差异。结果表明:新绿洲农田深层渗漏及NO3--N的淋失主要发生在苗期-拔节期以及休耕期,深层渗漏年损失量97.65-105.1 mm,占年灌溉水总量(810 mm)的12%-13%,NO_(3)^(-)-N淋溶年损失量68.1-123.8 kg·hm^(-2),占年施氮总量的18.7%-34.2%,休耕期灌水致使生育期内土壤中大量积累的氮素淋溶至深层,NO3--N淋失量是当年生育期内NO_(3)^(-)-N淋失量的2.2倍;开垦年限较长的老绿洲农田在相同灌溉施肥条件下无深层渗漏和NO_(3)^(-)-N的淋失现象发生,其“蓄水保墒”及抑制水分和NO_(3)^(-)-N渗漏淋失的生态效应优于开垦年限较短的新垦绿洲农田。因此,为降低土壤水分损失和NO_(3)^(-)-N淋失风险,建议新绿洲农田生育期内减少春季灌溉次数或降低灌水定额,冬季休耕期降低灌水定额或采取免冬灌措施,以此保证灌溉水资源的优化利用并减少农田氮素的淋失。 相似文献
10.
鲁西北平原夏玉米产量与土壤硝态氮淋失 总被引：7，自引：0，他引：7
供水量和氮肥施用量是影响农田硝态氮淋失的主要因素。本文通过田间小区试验,研究了水分和氮肥用量对夏玉米产量和土壤硝态氮的影响。试验表明,高水处理（0～50cm平均含水量控制在85%FC,FC为田间持水量032）和低水处理（0～50cm平均含水量控制在70%FC）间产量差异不显著,施肥量（0、100、200、和300kgNha-1）则具有显著影响,并且在200kgNha-1左右时达到最高产量;高水条件下土壤水分硝态氮下渗强,运移深度大,所有施肥处理在200cm处的土壤水硝态氮浓度都要高于国家饮用地下水标准10mgNL-1;低水条件下水分下渗弱,运移深度小于高水处理,但是在200cm处,200、300kgNha-1处理的土壤溶液硝态氮浓度依然高于10mgNL-1。 相似文献
11.
沙层特性对沙盖黄土坡面产流产沙变化贡献的定量分析 总被引：1，自引：0，他引：1
沙盖黄土坡面产流产沙方式独特,侵蚀过程复杂,量化降雨过程中该类坡面产流产沙变化影响因素贡献的大小对揭示其侵蚀机理具有重要的意义。基于室内模拟降雨试验,定量分析沙层厚度（2 cm、5 cm和10 cm）和粒径组成（100%粒径≤ 0.25 mm、75%粒径≤ 0.25 mm +25%粒径> 0.25 mm、50%粒径≤ 0.25 mm+50%粒径> 0.25 mm、未处理原沙和100%粒径> 0.25 mm）在降雨过程中对产流产沙变化的影响和贡献。结果显示：沙层厚度增加能明显延长产流时间,减少总产流量,增加总产沙量,增大降雨过程中产流产沙的变异性;随沙层粒径组成变粗,初始产流时间和产沙量无明显变化规律,产流量有增大趋势。沙层厚度、粒径组成及二者交互作用对初始产流时间变化的贡献率分别为68.03%、15.77%和3.85%。沙层厚度对降雨不同时段15 min产流量和不同历时总产流量的贡献率分别在23.89%~52.22%和41.10%~48.94%之间,对相应产沙的贡献率分别在29.19%~62.01%和13.53%~30.31%之间。整体上沙层粒径组成变化对产流产沙量变化的贡献率小于沙层厚度,且无明显规律。沙层厚度和粒径组成交互作用对产流量和降雨中前期产沙量的影响显著（p < 0.05）,其对产流产沙变化的贡献率分别在13.12%~26.62%和3.22%~43.12%之间,不同降雨时段变化明显。研究结果说明,沙层厚度决定沙盖黄土坡面产流产沙过程,其和沙层粒径组成对产流产沙的影响和贡献随坡面沙层的侵蚀演化而动态变化,且二者的交互作用也不容忽视。 相似文献
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The Impact of Erosion on Soil Productivity—An Experimental Design Applied in São Paulo State, Brazil
Anna Tengberg Michael Stocking & Sonia Carmela Falci Dechen 《Geografiska Annaler: Series A, Physical Geography》1997,79(1-2):95-107
Soil erosion is the principal threat to agricultural sustainability, affecting both the characteristics of the in situ soil and its productive potential. However, soils vary in their resilience and there are very few empirical data upon which to appreciate the degree and type of impact on the soil caused by erosion. This paper describes an experiment designed to generate such data based on soil loss and runoff plots, and it reports on nearly nine years of experience with the design at the Instituto Agronômico, Campinas, Brazil on a Latosol (Oxisol). After seven years of erosion induced by four levels of artificial cover, the effective rainfall on the most eroded soil was 20 percent less than on the control full cover. Crop yields were also found to be significantly affected: in 1995 by nearly 700 kg/ha and in 1996 by over 1000 kg/ha—a 50% decline in yield, amounting to a loss of 4 kg/ha of maize per tonne of cumulative soil loss. Losses of nutrients (organic C, P, K, Ca and Mg) in the runoff and eroded soil were also significant with far higher levels of loss associated with the eroded sediment. Changes in the in situ soil were less clear, but a test of trends showed that the decreases in organic matter and increases in acidity could unambiguously be attributed to soil erosion. Average enrichment ratios of the eroded sediment were 1.3 for organic C, 2.6 for P, 0.7 for K, 1.3 for Ca and 1.2 for Mg. Erosion has also affected the maize quality—mainly N, Ca and B nutrient content. Through these various measures, we conclude that seven years of induced erosion has had a marked effect on soil productivity, and for the first time we are now in a position to begin calculating the financial impact of the erosion process on future yields and farmer livelihoods. 相似文献
13.
M. A. Khan 《Journal of Arid Environments》1999,42(4):281
Surface runoff, sediment output, and input and output of precipitation nutrients were studied in ber (Zizyphus mauritiana) and pomegranate plantations in the Indian arid zone of Rajasthan during 1993–96. Over 77% of rainfall events were small with low intensity and prolonged duration. High magnitude rainfall (>50 mm) accounted for less than 2% of the rainfall events. Surface runoff was significantly different across the plantations and size of micro-watersheds. Average surface runoff was less than 10% of incidental rainfall, indicating the prominence of deep percolation. Sediment output was positively related to surface runoff. Rainfall added a significant amount of nutrients to the orchards. The extra-system of input was greater than loss through surface runoff plus sediment output. Nutrient loss as particulate matter was more than in solution. 相似文献
14.
坡地土壤氮素与降雨、径流的相互作用机理及模型 总被引：58，自引：0，他引：58
坡地土壤氮素径流损失表现为两种形式 ,溶解于径流中的矿质氮随径流液流失 ,吸附于泥沙颗粒表面以无机态和以有机质形式存在的氮素。坡地土壤氮素流失过程实际上是表层土壤氮素与降雨、径流相互作用的过程 ,土壤氮素流失的多少主要受相互作用的限制。从分析土壤与降雨、径流相互作用入手 ,分析了土壤氮素与降雨、径流相互作用过程及机理 ,并对相互作用模型进行探讨。 相似文献
15.
Jin Changxing 《地理学报(英文版)》1994,(Z2)
1.IntroductionWuhuaCounty,locatedintheupstreamOfHanjianghiver,isoneofthemostseriouslyerodedcountiesinSouthChinagraniticweatheringregionOfGUangdOngPrOvince.ByinveStighion,thetOtalerodedareaisestimatedtobe875.33km,whichoccupiedbot30percentofthetOtalerodedareaoftenmostseriouserodedcountiesintheregion.Insomeconununes,theeroddareaevenreachedtomorethan6Opercent.ErosionresuItedinwidesPedOfbemountalns,landdopadaion,shortOfwterresourceshoperecotw.~ngthethreetypesoferosionintheupstreamOfHanjian… 相似文献
16.
Serious soil erosion has already resulted in degradation of the Loess Plateau of China. Soil erosion is commonly accompanied by extensive soil nutrient loss. Because of enrichment processes, sediment nutrient content is often higher than that of natural soil. The objective of this study is to determine the enrichments of organic matter and total nitrogen in sediment in hilly and gully loess areas on the Loess Plateau of China. Measurements of enrichment ratios (ER) of organic matter (EROM) and total nitrogen (ERTN) in sediment as affected by rainfall, slope gradient, tillage, and fertilization were made in the field under natural rainfall conditions. The results showed that the enrichment of clay in sediment resulted in the enrichment of organic matter (OM) and total nitrogen (TN) in sediment. The averages of sediment clay ER, EROM and ERTN for the various slope gradients were 1.77, 2.09 and 1.61, respectively. The soil erosive module was negatively correlated with EROM and ERTN. Our results indicate that measures to reduce soil erosion, i.e. reducing rainfall erosivity, decreasing soil slope gradient, decreasing fertilizer use, and using level trenches, may increase EROM and ERTN. Both quantity and quality of sediment yield should be considered when implementing erosion control measures. 相似文献
17.
Relations between interrill erosion processes and sediment particle size distribution in a semiarid Mediterranean area of SE of Spain 总被引：10，自引：0，他引：10
Erosion and sediment characteristics were measured using simulated rainfall on two cultivated soils of contrasting lithology (Quaternary calcareous colluvium and Tertiary marls) in a semiarid Mediterranean area of SE Spain. Two rainfall intensities, high (56.0±2.4 mm h−1) and medium (31.4±1.4 mm h−1), were used in order to know the mechanisms involved in each selected condition. For each simulated event, runoff and sediment were sampled at 1-min intervals on a 1-m wide by 2-m long erosion plot. The erosion rate was calculated as the total amount of soil lost divided by the time period of the test. The duration of the test was that needed to reach steady state runoff, an average time of 24.5 min for Quaternary calcareous colluvium and 17.7 min for Tertiary marls. The size distribution of the transported sediment in the field (effective size distribution) was compared with equivalent measurements of the same samples after chemical and mechanical dispersion (ultimate size distribution) to investigate the detachment and transport mechanisms involved in sediment mobilisation. The results showed that the soil type determined the hydrological response, regardless of the rainfall intensity. The erosional response was, however, determined by the rainfall and soil surface characteristics.In Quaternary calcareous colluvial soils, the predominant erosion process depended on the rainfall intensity, with a prevailing detachment-limited condition in high-intensity events and prevailing transport-limited conditions in those events of medium intensity. These differences in the main erosion processes were reflected in the size of the transported material and in the change in sediment size within the storm. Thus, a time-dependent size distribution of the eroded material (decreasing coarse fractions and increasing fine fractions with runoff time) was observed for high-intensity events. In medium-intensity events, on the other hand, the time-independent size distribution of the eroded material indicated transport-limited erosion.Due to the rapid surface crusting on the Tertiary marl soil, no differences in the main erosion processes or in the sediment size distribution occurred for the different rainfall intensities tested. The erosion of marl soils was determined mainly by the limited quantity of available sediment.The effective size of material was a more sensitive parameter than the ultimate size of the sediment to study the way in which the sediment was transported. 相似文献
18.
Serious soil erosion has already resulted in degradation of the Loess Plateau of China. Soil erosion is commonly accompanied by extensive soil nutrient loss. Because of enrichment processes,sediment nutrient content is often higher than that of natural soil. The objective of this study is to determine the enrichments of organic matter and total nitrogen in sediment in hilly and gully loess areas on the Loess Plateau of China. Measurements of enrichment ratios (ER) of organic matter (EROM) and total nitrogen (ERTN) in sediment as affected by rainfall, slope gradient, tillage, and fertilization were made in the field under natural rainfall conditions. The results showed that the enrichment of clay in sediment resulted in the enrichment of organic matter (OM) and total nitrogen(TN) in sediment. The averages of sediment clay ER, EROM and ERTN for the various slope gradients were 1.77, 2.09 and 1.61, respectively. The soil erosive module was negatively correlated with EROM and ERTN. Our results indicate that measures to reduce soil erosion, i.e. reducing rainfall erosivity, decreasing soil slope gradient, decreasing fertilizer use, and using level trenches, may increase EROM and ERTN. Both quantity and quality of sediment yield should be considered when implementing erosion control measures. 相似文献
19.
1IntroductionResearch results have shown that overland flow firstly removes fine particles of topsoil because the fine soil particles can be easily transported in runoff (Burwell etal., 1975; Alberts etal., 1983; Gregory 1991). The component differences of fine soil particles between the sediment resulting from soil erosion and the original soil were studied (Meyer etal., 1975; Loch etal., 1982; Cogo, 1983). Sediment was normally composed of soil aggregates and particles of different diamet… 相似文献
20.
我国水土流失典型区土壤表土结皮敏感性 总被引：6，自引：0，他引：6
表土结皮是降雨与土壤共同作用下的产物,某一土壤是否结皮、结皮的敏感程度如何,取决于该土壤的性质及所处地区的降雨情况。我国广泛分布着多种理化性质迥异的土壤,尤其是黄土、紫色土、红壤和黑土分布在我国水土流失严重的区域。但是,土壤发育表土结皮的敏感性很少见报道。本文通过分析模拟降雨试验结果及前人研究结论,提出了影响表土结皮发育敏感性的3个关键因素,并基于此对我国四大水土流失典型区土壤表土结皮的敏感性进行了分析。研究表明:细颗粒,尤其是粉粒是表土结皮发育的物质基础;团聚体稳定性是表土结皮发育快慢及程度的决定因素;高强度降雨是表土结皮发育的必要条件。黄土高原地区土壤极易发育表土结皮,四川紫色土区土壤发育表土结皮的概率大,南方红壤区除花岗岩、页岩外其他母岩上发育的土壤很难发育表土结皮,东北典型黑土不发育表土结皮,而非典型黑土易发育表土结皮。 相似文献