黄土高原区域尺度农田土壤质量评价

发布时间：2018-05-28 05:10

  本文选题：土壤质量 + 黄土高原　； 参考：《西北农林科技大学》2017年硕士论文

【摘要】：从区域尺度了解黄土高原农田土壤质量特征,探讨该区农田土壤质量影响因素,对区域农业发展具有重要意义。本研究依据黄土高原生态、农业及土壤区划,结合土地利用、种植制度、地貌、土类及气候类型等多专题数据,按照“农田类型-地形-土类”主体组合,将黄土高原划分为关中平原区、渭北高塬区、丘陵沟壑区、银川平原区、浅山丘陵区五个农业区。根据“农田类型—地形—土类”主体组合区域代表性,在上述类型区选取陕西武功、甘肃宁县、甘肃庄浪、宁夏平罗、青海乐都作为典型县,通过布点采样和分析测定,对黄土高原不同农业类型区农田土壤质量评价指标最小数据集及其尺度效应、有机碳与理化属性关系进行较深入的研究,以典型县为基础、组合斑块为单元,建立了尺度上推模型,获取了区域尺度农田土壤质量及其空间分布特征,得出以下主要结论:1.分析了黄土高原不同农业类型区典型县农田土壤理化特征。武功县、宁县农田土壤质地较为均一,以粘壤土和壤土为主,庄浪县和乐都质地较其他县域粗糙,以壤土、砂粘壤土、砂壤土为主;平罗县由于引黄灌溉导致土壤质地变异较大;武功、平罗农田亚表层土壤压实问题突出,其均值分别为1.58g/cm3和1.46g/cm3;各典型县pH均在8以上,整体偏碱性;乐都、武功、平罗土壤全量养分及有效磷含量明显高于庄浪及宁县,速效钾含量在各典型县之间无显著性差异;宁县农田土壤有机质含量显著低于其他县域,以乐都县有机质含量最高。庄浪县有机质含量处在各典型县中上水平,其磷钾含量显著低于其他县域水平。2.黄土高原不同地貌类型区农田土壤有机碳与理化属性的相关性存在较大差异,且受气候和管理措施影响的程度不同,整体来看,全氮是黄土高原全区及各县域农田土壤有机碳的重要影响因子。不同地貌类型区农田土壤有机碳与pH、砂粒呈显著负相关关系,与粉粒、全氮、全钾呈显著正相关关系,该相关性受气候和管理措施影响较小;与容重、粘粒负相关,与全磷、有效磷、速效钾正相关,该相关性受气候和管理措施影响较大;农田土壤有机碳与粘粒含量的相关关系和粘粒含量有关,当粘粒含量为20%～25%,有机碳与粘粒的相关性较高,当粘粒含量大于30%时,有机碳与粘粒呈负相关趋势。在区域尺度上,全氮、容重、全磷是影响农田土壤有机碳的重要因子,在各个地貌类型区中,全氮是影响农田土壤有机碳含量的重要因子。关中平原区、渭北高塬区、丘陵沟壑区、银川平原区、浅山丘陵区有机碳处于最高水平时的全氮阈值分别为1.39、0.95、1.33、1.38、1.64 g/kg,有机碳处于低级水平的全氮阈值分别为0.97、0.59、0.86、0.76、1.06 g/kg。3.指标变异性随尺度的变化而发生变化,不同空间的土壤质量指标最小数据集评价结果存在尺度效应。在不同尺度间,容重、pH、全钾、碳氮比变化较小,其余指标整体呈现出变异性随尺度增大而增大的趋势。通过分析指标变异性影响因素可知,指标变异性受到自然因素及人为因素的双重影响,但影响程度有所不同。相对于单因素对土壤质量指标的影响,综合影响因素对指标的影响更大,这也表明,指标的变异性不仅仅是单因素的作用结果,而是多个因素相互作用造成的。所以,在进行土壤质量评价时,应综合考虑多方面因素,尤其是在研究尺度范围内,地形、土类、管理措施多样性程度较高时。此外,气候类型及农田管理措施在尺度上推或下推过程中均会发生相应变化,这导致土壤质量指标的变异性与相关性也随之变化,最终导致不同空间尺度所筛选的最小数据集评价指标的代表性存在尺度效应。在指标筛选过程中,应充分重视针对性和区域性原则,所选指标应能够反映区域问题,进而在降低成本的前提下提高土壤质量评价的准确度和应用性。4.以典型县为基础、“农田类型—地形—土类”组合斑块为单元,建立了尺度上推模型,从区域尺度上探讨了黄土高原农田土壤质量及其空间分布特征。从区域尺度上来看,黄土高原全区农田土壤有机质、全氮含量匮乏,全磷、全钾、速效钾和表层有效磷含量相对充足,处于较高水平,丘陵沟壑区亚表层有效磷含量极其缺乏。关中平原区农田土壤压实问题突出,表层土壤有43%的面积处在1.4～1.5g/cm3之间,亚表层有97%的面积处于1.5～1.6g/cm3之间,此外,银川平原区和渭北高塬区亚表层土壤分别有84%和45%的面积容重值处于1.4～1.5g/cm3之间。以黄土高原地区最高农田土壤质量作为参照,全区以五级和六级为主,面积占比分别为79%、20%,主要分布在关中平原区、汾河谷地、晋西豫北山地、渭北高塬区、丘陵沟壑区中部和西南部及银川平原区的西部。六级土壤质量主要分布在丘陵沟壑区。亚表层土壤质量以六级(57%)和七级(31%)为主,六级土壤质量主要分布在渭北高塬区和银川平原区西部,丘陵沟壑区六级和七级分别占55%和45%,在关中平原区和银川平原区的东部土壤质量为八级和九级,土壤质量较低。
[Abstract]:It is of great significance for regional agricultural development to understand the soil quality characteristics of farmland in the Loess Plateau and to explore the influence factors of farmland soil quality in this area. This study is based on the loess plateau ecology, agricultural and soil zoning, land use, planting system, geomorphology, soil types and climate types, according to "farmland type". The Loess Plateau is divided into Guanzhong Plain, Wei Bei highland area, hilly gully area, Yinchuan plain area, and Shallow Mountain hilly area five agricultural areas. According to the representative area of "farmland type topographic soil", Shaanxi Wugong, Gansu Ning County, Gansu Zhuanglang, Ningxia Pingluo and Qinghai Province are selected. As a typical county, Ledu, as a typical county, studied the relationship between the minimum data set and the scale effect of soil quality evaluation index and the relationship between organic carbon and physicochemical properties of the farmland soil quality evaluation index in different agricultural types area of the Loess Plateau, based on the typical county and the combination spot block as the unit, the scale push model was established and the area was obtained. The main conclusions are as follows: 1. the soil physical and chemical characteristics of the typical counties of different agricultural types in the Loess Plateau are analyzed. In Wugong County, the soil texture of farmland is relatively uniform, mainly in clay loam and loam soil, and the texture of Zhuanglang county and loam is rough, with loam, sand and clay loam. The sandy loam soil is the main soil, and the soil texture variation caused by irrigation of Yellow River in Pingluo County is large, and the subsurface soil compaction problem of Wu Gong and Pingluo farmland is 1.58g/cm3 and 1.46g/cm3 respectively. The pH of each typical county is above 8 and the whole is alkaline; Ledu, Wu Gong, the total nutrient and effective phosphorus content of the soil in Pingluo is obviously higher than that in Zhuanglang and the county of Ning county. There is no significant difference in the content of effective potassium between the typical counties. The content of organic matter in farmland soil is significantly lower than that of other counties, and the organic matter content in Ledu county is the highest. The content of organic matter in Zhuanglang county is in the middle and upper levels of the typical counties, and the content of phosphorus and potassium is significantly lower than that of the other county level.2. Loess Plateau different landform areas. The correlation of carbon and physicochemical properties is different, and the extent of the influence of climate and management measures is different. Overall, total nitrogen is an important influence factor of soil organic carbon in the whole region of the Loess Plateau and the counties of various counties. The soil organic carbon in different landform types is negatively correlated with pH, and with powder, total nitrogen and total potassium. Significant positive correlation, the correlation was less affected by climate and management measures; negatively correlated with bulk density, clay grain, positive correlation with total phosphorus, available phosphorus, and available potassium; the correlation was greatly influenced by climate and management measures; the correlation between soil organic carbon and clay content was related to clay content, when the clay content was 20% to 25%, organic carbon and organic carbon. The correlation of clay particles is higher. When the content of clay is greater than 30%, organic carbon and clay have a negative correlation. At the regional scale, total nitrogen, bulk density and total phosphorus are important factors affecting the organic carbon of farmland soil. In the various geomorphic regions, the total nitrogen is an important factor affecting the organic carbon content of farmland soil. The total nitrogen threshold of organic carbon at the highest level in the gully area, Yinchuan plain and the hilly area of the shallow mountain area is 1.39,0.95,1.33,1.38,1.64 g/kg, and the total nitrogen threshold of organic carbon at the lower level is 0.97,0.59,0.86,0.76,1.06 g/kg.3. index variation with the scale change, and the minimum number of soil quality indexes in different spaces is the smallest. According to the evaluation results, there is a scale effect. In different scales, the changes of bulk density, pH, total potassium and carbon and nitrogen ratio are small, and the other indexes generally show a tendency to increase with the scale increasing. By analyzing the factors of variability, the index variability is influenced by the dual effects of natural factors and human factors, but the degree of influence is not good. Compared with the influence of single factor on soil quality index, the influence factors have greater influence on the index, which also indicates that the variability of the index is not only the result of single factor, but the interaction of several factors. Therefore, in the evaluation of soil quality, many factors should be taken into consideration, especially in the study scale. In the range, terrain, soil, and management measures have a high degree of diversity. In addition, the climate types and farmland management measures will change correspondingly during the scale push or push process, which leads to the variation and correlation of soil quality indicators, which eventually leads to the minimum data set evaluation index selected from the spatial scale. In the process of index screening, we should pay full attention to the principle of targeted and regional. The selected indexes should be able to reflect the regional problems, and then improve the accuracy and application of soil quality evaluation on the premise of reducing the cost, based on the typical county, and "farmland type topography soil" combination patch as the unit of.4.. On the regional scale, the soil organic matter and total nitrogen content are deficient, and the total phosphorus, total potassium, available potassium and surface available phosphorus content are relatively sufficient, at a high level, and the subsurface of the hilly and gully region. The content of effective phosphorus is extremely deficient. The soil compaction problem in Guanzhong plain area is prominent, the surface soil has 43% area between 1.4 and 1.5g/cm3, the subsurface area has 97% area between 1.5 and 1.6g/cm3, in addition, the surface soil bulk density of 84% and 45% of the subsurface soil of Yinchuan plain and Weibei Highland area is between 1.4 and 1.5g/cm3 respectively. According to the soil quality of the highest farmland in the Loess Plateau, the area is mainly five and six, and the area occupation ratio is 79%, 20% respectively. It mainly distributes in Guanzhong Plain, Fenhe Valley, northern Shanxi, Weibei high tableland, central and southwest of hilly gully area and the west of Yinchuan plain area. The soil quality of grade six is mainly distributed in the hilly area. The subsurface soil quality is six grade (57%) and seven grade (31%). The six grade soil quality is mainly distributed in the Weibei highland and Yinchuan plain, six and 45% in the hilly and gully region respectively. The soil quality of the eastern part of Guanzhong Plain and Yinchuan plain is eight and nine, and the soil quality is low.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S151.9
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本文编号：1945410