【作者】 张孝存；

【导师】 郑粉莉；

【作者基本信息】 陕西师范大学 ， 自然地理学， 2013， 博士

【摘要】 东北黑土区是我国主要的粮食产区和商品粮基地。近年来,该区土壤侵蚀的加剧已严重影响区域粮食生产,对我国粮食战略安全构成了严重威胁。因此,分析黑土区土壤侵蚀—沉积对土壤质量和作物产量的影响,对保护黑土资源和保障国家粮食安全具有重要意义。本研究运用野外调查、室内分析与数理统计、核素示踪和GIS技术相结合的方法,以典型黑土区松花江流域东山沟小流域为研究对象,分析了流域侵蚀—沉积空间分布特征,研究了侵蚀—沉积对土壤物理学、化学性质和生物学特性的影响；筛选了侵蚀环境下土壤质量评价指标,并构建了评价模型,探究了侵蚀—沉积和土壤质量对玉米产量的影响。主要研究结论如下：(1)研究流域侵蚀—沉积空间分布特征,发现土壤侵蚀强度在流域分布呈现上游>中游>下游的分布规律,上游区域以土壤侵蚀现象为主,中游区域侵蚀与沉积现象并存,下游区域主要发生土壤沉积现象。土壤侵蚀强度沿坡面分布呈现坡中部>坡顶部>坡上部>坡下部,呈现明显的侵蚀强弱交替变化规律。(2)分析了土壤团聚体水稳性的分布特征及其破碎机制。研究发现,黑土土壤团聚体破碎机制主要是消散作用,其次是黏粒膨胀作用。耕层土壤的团聚体稳定性沿坡面呈波动变化趋势,分析了土壤有机质和黏粒含量及开垦年限对土壤团聚体稳定性的影响。(3)研究流域土壤侵蚀对土壤养分、土壤酶活性和土壤微生物量的影响。结果表明,流域土壤有机质、全氮、碱解氮、速效磷、转化酶、脲酶、碱性磷酸酶和微生物量碳氮空间分布特征明显受土壤侵蚀影响。总体上,流域土壤养分、酶活性和微生物量均呈现由上游至下游增加的趋势,沿坡长分布呈现坡顶较高—坡上较低—坡中低—坡下高的变化趋势。流域土壤有机质、全氮、转化酶与土壤侵蚀速率呈极显著负相关,土壤碱解氮、微生物量碳和氮含量与土壤侵蚀速率呈显著负相关,土壤脲酶和碱性磷酸酶与土壤侵蚀速率存在负相关关系,说明土壤侵蚀是影响土壤养分含量、酶活性和微生物量下降的重要因素。(4)筛选侵蚀环境下土壤质量评价指标并构建了评价模型。基于相关分析、敏感性分析和主成分分析,取土壤微生物量碳氮、速效磷、转化酶、脲酶、碱性磷酸酶、有机质、全氮、碱解氮、阳离子交换量、MWDsw、>0.2mm水稳性团聚体、砂粒作为土壤质量评价的基本指标。选取土壤团聚体平均重量直径MWDsw、>0.2mm水稳性团聚体含量、土壤有机质、全氮、碱解氮、速效磷、转化酶和微生物量碳作为土壤质量评价的适宜指标。经判别分析,筛选土壤转化酶、有机质、全氮、碱解氮和MWDsw为表征土壤质量的关键指标并构建了基于不同指标体系的土壤质量评价模型。土壤质量指数(SQI)计算结果表明,研究区土壤质量退化严重,总体处于较低水平。土壤质量在流域分布表现为流域下游区域>中游区域>上游区域,沿坡长分布呈现中—较低—低—高的变化趋势。SQI与侵蚀速率呈现极显著性负相关关系,表明流域土壤侵蚀不仅对土壤质量空间分布有重要影响,也是导致土壤质量贫瘠化最直接最重要的原因。(5)分析土壤质量和土壤侵蚀对玉米产量的影响。结果表明,玉米产量在流域尺度表现为由流域下游向上游降低的趋势,沿坡长分布呈现坡下部>坡顶部>坡上部>坡中部。流域坡面侵蚀区玉米产量明显低于流域沉积区,流域玉米地总体以玉米中低产田为主。玉米产量与土壤质量呈现极显著性正相关关系,表明土壤质量对玉米产量的高低和空间分布有积极作用,而土壤侵蚀则有负向影响。更多还原

【Abstract】 The black soil region in Northeast China is the main grain production area and commodity grain base of China. In recent years, soil erosion has become more and more serious, which greatly affects regional food production and food security of our country. Therefore, revealing the effects of soil erosion-deposition on soil quality and crop yield in the black soil area had become more important for protecting the valuable black soil and guarantee food security of China. This dissertation took Dongshangou watershed, located at Songhua River Basin of typical eroded black soil area of Northeast China, as a research area site. According to field investigation combining with laboratory analysis, mathematical statistical analysis, radioisotope tracer and GIS technology, the dissertation analyzed the spatial distribution characteristics of soil erosion-deposition, studied the influence of soil erosion-deposition on soil physical, chemical and biological characteristics, determined soil quality assessment indicators under erosion environment and established evaluation model, and then explored the effect of soil erosion-deposition and soil quality on maize yield. The main results were as follows:(1) Spatial distribution characteristics of soil erosion-deposition were studied. The results showed that soil erosion rate in the watershed was ordered as follows upperstream>downstream> middle. Soil erosion was dominated in upper stream area, erosion and deposition was coexisted in middle reaches area, soil deposition was dominated in downstream area. Erosion rate along slope length followed as:middle slope position> crest position> upper slope position> lower slope position.(2) The distribution characteristics of soil water-stable aggregate ability and broken mechanism were analyzed. Results showed that aggregate breakdown in black soil was mainly caused by the compression of air entrapped inside aggregates, the second was clay swelling during wetting. The soil aggregate stability of plough layer was fluctuated along the slope surface.Then the effects of soil organic matter, clay particles content and reclamation duration on soil aggregate stability were analyzed.(3) Effects of soil erosion on soil nutrient, soil enzyme activities and microbial biomass C and N were studied. Results showed that spatial distribution of soil organic matter, total nitrogen, available nitrogen, available phosphorus, invertase, urease, alkaline phosphatase and microbial biomass C and N were significantly affected by erosion. In the mass, soil nutrient, soil enzyme activities and microbial biomass C and N was increased from upperstream to downstream in watershed and the variation tendency ordered as follows:higher(top-slope)-lower(up-slope)-low(mid-slope)-high(down-slope) along the slope surface. The relationship between soil erosion rate and soil organic matter, total nitrogen, invertase was highly significant negative correlation. Soil erosion rate had significant negative correlation with available nitrogen content, microbial biomass carbon and nitrogen content, and had negative correlation with urease and alkaline phosphatase. Thus, soil erosion is the important factor that can affect soil nutrient, soil enzyme activities and microbial biomass.(4) Soil quality assessment indicators were selected, and assessment model was established under erosion environment. Based on correlation analysis, sensitivity analysis, the dissertation chose MWDsw,>0.2mm soil water-stable aggregate,sand, soil organic matter, total nitrogen, available nitrogen, rapid available phosphorus, CEC, invertase, urease, alkaline phosphatase soil microbial biomass carbon and nitrogen as base indicators for soil quality evaluation. According to principal component analysis, the dissertation chose MWDsw,>0.2mm soil water-stable aggregate, soil organic matter, total nitrogen, available nitrogen, rapid available phosphorus, invertase and soil microbial biomass carbon as appropriate indicators for soil quality evaluation. According to discriminant analysis, soil invertase, organic matter, total nitrogen, available nitrogen and MWDsw were selected as key soil quality indicators and soil quality evaluation model which based on different index system was established. The calculation results of the soil quality index (SQI) showed that soil quality had degenerated seriously and stayed at low level in the study area. The distribution manifestation of soil quality is as follows:downstream of the watershed>middle reaches of the watershed>upstream of the watershed, and the variation tendency ordered as follows:middle-lower-low-high along slope length. SQI had highly significant negative correlation with soil erosion rate, which indicated the soil erosion intensity had important influence on spatial distribution of soil quality, and it was the most important and direct reason that led to soil quality impoverishment.(5) Effects of soil quality and soil erosion on maize yield were analyzed. Results showed that, maize yield was decreased from downstream to upstream, and the variation tendency ordered along slope length as follows:down-slope> top-slope> up-slope> mid-slope. Maize yield in soil erosion area were significantly lower than deposition area in the watershed, and it was mainly the middle-and-low-yield farmland in maize field. Maize yield had a highly significant positive correlation with soil quality. The results indicated that soil quality had a positive effect on the level and spatial distribution of maize yield.On the contrary, soil erosion had a negative effect on them.更多还原