娑婆小流域坡耕地氮素流失特征与防治对策研究

发布时间：2018-01-12 02:05

本文关键词：娑婆小流域坡耕地氮素流失特征与防治对策研究　出处：《山西农业大学》2016年博士论文　论文类型：学位论文

【摘要】：汾河水库是山西省最大的饮用水水源地。长期以来,水库上游地区坡耕地耕种十分普遍,加上严重的水土流失,使土壤养分随径流泥沙流入汾河进而进入汾河水库,导致水库水体富营养化问题日益突出。研究汾河水库上游坡耕地土壤侵蚀、养分流失及防治问题,对维系水源地水土资源功能、改善生态环境,具有十分重要的意义。本研究以汾河水库上游静乐县娑婆小流域坡耕地为研究区域,在坡耕地布设径流监测小区,以不同作物条件下坡耕地坡面径流量、泥沙流失量、养分流失形态及流失量为主要研究内容。在调查和评价小流域土壤资源理化性状、土地利用结构、主要污染物负荷的基础上,通过采用水土流失动态监测、室内外模拟试验等方法,对不同作物条件下坡耕地产流产沙机理、面源污染形成过程、氮素流失特征进行了定性和定量分析,进而明确不同作物对坡耕地径流、泥沙形成及氮素流失的影响,在此基础上对大面积坡耕地氮素流失量进行了估算。本研究首次提出坡耕地作物缓冲带措施,并对作物缓冲带在防控氮素流失等方面进行了研究分析,初步提出坡耕地防控面源污染的思路和对策。主要结论有：(1)作物类型对泥沙流失量具有显著影响,是影响泥沙流失量的因素之一。不同作物在相同有效降雨条件下形成的泥沙流失量之间差异较大,且随着时间推移低秆作物莜麦地、土豆地及裸地呈现逐渐下降的趋势,而高秆作物玉米地和弃耕地有逐渐增加的趋势。(2)在监测时段内,除裸地外,NO_3~--N浓度基本呈现逐渐下降的趋势：裸地玉米地莜麦地土豆地弃耕地;TN浓度大体呈现先增长后下降的趋势,而且不同作物之间存在一定差异：裸地土豆地弃耕地玉米地莜麦地;NO_2~--N浓度呈现先上升后下降的趋势,不同作物之间存在一定差异：裸地土豆地莜麦地玉米地弃耕地；NH4+-N浓度变化为先升高,后降低再升高的趋势,不同作物间存在一定差异：莜麦地弃耕地玉米地土豆地裸地。不同作物条件下径流中NO_3~--N和TN浓度具有显著差异,而NO_2~--N和NH4+-N的浓度不存在显著差异。(3)试验小区10m~2内随径流流失的三种无机氮之间差异较大,表现为：裸地土豆地弃耕地莜麦地玉米地。不同作物条件下随径流流失的NO_3~--N量和NO_2~--N量具有显著差异,而NH4+-N流失量之间没有显著差异。(4)随径流流失的有机氮大致为逐渐增长趋势,且不同作物之间差异显著。有机氮流失量：裸地土豆地弃耕地莜麦地玉米地。全氮流失量：裸地土豆地弃耕地莜麦地玉米地。(5)监测时段内流失的NO_3~--N占TN的比例呈逐渐下降的趋势,玉米地裸地莜麦地弃耕地土豆地;流失N02--N占TN的比例呈先上升后下降再上升,裸地土豆地弃耕地莜麦地玉米地；流失NH4+-N占TN的比例呈逐渐下降的趋势：莜麦地玉米地弃耕地土豆地裸地；有机氮所占全单比例：土豆地弃耕地裸地莜麦地玉米地。(6)在雨季,不同作物条件下每公顷坡耕地流失泥沙量：裸地土豆地莜麦地弃耕地玉米地。娑婆小流域每年几百至上千吨泥沙从坡面流失,严重影响了土地生产力可持续发展,对下游河道和水库造成淤积。(7)在雨季,不同作物条件下每公顷坡耕地流失TN量：裸地土豆地弃耕地莜麦地玉米地。娑婆小流域每年数十吨的氮素从坡面流失,加剧了坡耕地土壤的贫瘠化。(8)针对娑婆小流域土壤资源、土地利用结构以及传统农业种植特点,提出构建地埂植物带、作物缓冲带等技术措施和坡耕地改梯田、扩大林草面积改善该流域土地利用结构的发展思路。试验证明,坡耕地布设作物缓冲带能有效削减径流、泥沙和氮素流失。
[Abstract]:Fenhe Reservoir is the water source of drinking water in Shanxi Province, the largest. For a long time, the reservoir slope land in the upper reaches of farming is widespread, and water and soil erosion is serious, the soil nutrient runoff and sediment flows into the Fen River and then into the Fenhe Reservoir, leading to eutrophication problems have become increasingly prominent. The upper reaches of Fenhe Reservoir on soil erosion, nutrient loss and prevention, to maintain the water function of water and soil resources, improve the ecological environment, it has very important significance. This study in a small watershed upstream of Fenhe Reservoir jinglexian Saha slope land as the study area, the layout of slope farmland runoff monitoring area, crop conditions in different slope land runoff and sediment loss. The morphology and loss of nutrient loss is the main research content. In the investigation and evaluation of small watershed soil physicochemical properties, land use structure, main pollutants load On the soil erosion monitoring, indoor simulation test method of slope under different crop land runoff mechanism, the formation process of non-point source pollution, the characteristics of nitrogen loss through qualitative and quantitative analysis, and then clear the different crops on sloping farmland runoff, and nitrogen loss sediment formation, on the basis of a large area of farmland nitrogen loss was estimated. This is the first study to put forward measures of sloping land crops and crop of buffer zone, buffer zone was analyzed in the prevention and control of nitrogen loss, puts forward ideas and Countermeasures of prevention and control of non-point source pollution of arable land slope. The main conclusions are: (1) crop types on sediment loss the amount has a significant effect, is one of the factors affecting the sediment loss. Different crops in the same effective rainfall under the condition of soil erosion between different, and with time low Stalk crops naked oats, potatoes and bare land decreased gradually, while the high stalk crops of corn and abandoned farmland is a gradually increasing trend. (2) in the monitoring period, except that of bare land, NO_3~--N concentration decreased gradually: bare naked oats corn potato abandoned farmland wheat; the concentration of TN in general growth at first decline, but there are some differences between different crops: bare potatoes abandoned farmland corn oat NO_2~--N concentrations showed Medina; decreased, there are some differences between different crops: bare soil bean oats corn abandoned farmland; NH4+-N concentration increased first, then decreased increased, there were significant differences among different crops: corn and potatoes to naked oats in abandoned land to bare land. There were significant difference between different crop conditions in the runoff and the concentration of TN NO_3~--N, NO_2 ~--N and NH4+-N The concentration has no significant difference. (3) the difference between the three kinds of inorganic nitrogen in the test cell 10m~2 with the loss of runoff is large, as follows: bare potato corn oats. Abandoned farmland NO_3~--N quantity and NO_2~--N quantity under the condition of different crop losses with runoff had significant differences, but no significant difference between the amount of NH4+-N loss. (4) organic nitrogen losses with runoff are gradually increasing trend, and the difference was significant between different crops. The organic nitrogen loss amount of bare potato corn. Oat abandoned farmland nitrogen loss by: bare potatoes Medina corn. Naked oats abandoned farmland (5) in the monitoring period the loss of NO_3~--N TN the proportion decreased gradually, corn potatoes discarded cultivated land bare naked oats; the loss of N02--N TN ratio increased first and then decreased and then increased, bare potatoes abandoned farmland oats corn ground; NH4+-N loss percentage of TN A gradual downward trend: naked oats corn ground potato abandoned farmland bare land; total organic nitrogen ratio: single potato abandoned farmland corn. Bare naked oats (6) during the rainy season, the amount of sediment erosion under the conditions of different crops per hectare farmland: bare potato oat discarded cultivated land corn. This small every year hundreds of tons of sediment from the basin slope erosion, serious impact on the sustainable development of land productivity, siltation of downstream river and reservoir. (7) during the rainy season, the amount of TN loss under the condition of different crops per hectare farmland: bare potato abandoned farmland corn. This small oat basin every year dozens of tons of nitrogen from the soil the loss, exacerbated the impoverishment of soil slope land. (8) according to the soil resources in small watershed this, land use structure and traditional agricultural planting characteristics, proposed the construction of ridge plant, plant buffer zone and other technical measures In order to improve the development of the land use structure in the watershed, it is proved that the layout of crop buffer strips in sloping fields can effectively reduce runoff, sediment and nitrogen loss.

【学位授予单位】：山西农业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S157

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