發(fā)布時間：2018-05-28 05:10

  本文選題：土壤質量 + 黃土高原��； 參考：《西北農林科技大學》2017年碩士論文

【摘要】：從區(qū)域尺度了解黃土高原農田土壤質量特征,探討該區(qū)農田土壤質量影響因素,對區(qū)域農業(yè)發(fā)展具有重要意義。本研究依據黃土高原生態(tài)、農業(yè)及土壤區(qū)劃,結合土地利用、種植制度、地貌、土類及氣候類型等多專題數據,按照“農田類型-地形-土類”主體組合,將黃土高原劃分為關中平原區(qū)、渭北高塬區(qū)、丘陵溝壑區(qū)、銀川平原區(qū)、淺山丘陵區(qū)五個農業(yè)區(qū)。根據“農田類型—地形—土類”主體組合區(qū)域代表性,在上述類型區(qū)選取陜西武功、甘肅寧縣、甘肅莊浪、寧夏平羅、青海樂都作為典型縣,通過布點采樣和分析測定,對黃土高原不同農業(yè)類型區(qū)農田土壤質量評價指標最小數據集及其尺度效應、有機碳與理化屬性關系進行較深入的研究,以典型縣為基礎、組合斑塊為單元,建立了尺度上推模型,獲取了區(qū)域尺度農田土壤質量及其空間分布特征,得出以下主要結論:1.分析了黃土高原不同農業(yè)類型區(qū)典型縣農田土壤理化特征。武功縣、寧縣農田土壤質地較為均一,以粘壤土和壤土為主,莊浪縣和樂都質地較其他縣域粗糙,以壤土、砂粘壤土、砂壤土為主;平羅縣由于引黃灌溉導致土壤質地變異較大;武功、平羅農田亞表層土壤壓實問題突出,其均值分別為1.58g/cm3和1.46g/cm3;各典型縣pH均在8以上,整體偏堿性;樂都、武功、平羅土壤全量養(yǎng)分及有效磷含量明顯高于莊浪及寧縣,速效鉀含量在各典型縣之間無顯著性差異;寧縣農田土壤有機質含量顯著低于其他縣域,以樂都縣有機質含量最高。莊浪縣有機質含量處在各典型縣中上水平,其磷鉀含量顯著低于其他縣域水平。2.黃土高原不同地貌類型區(qū)農田土壤有機碳與理化屬性的相關性存在較大差異,且受氣候和管理措施影響的程度不同,整體來看,全氮是黃土高原全區(qū)及各縣域農田土壤有機碳的重要影響因子。不同地貌類型區(qū)農田土壤有機碳與pH、砂粒呈顯著負相關關系,與粉粒、全氮、全鉀呈顯著正相關關系,該相關性受氣候和管理措施影響較小;與容重、粘粒負相關,與全磷、有效磷、速效鉀正相關,該相關性受氣候和管理措施影響較大;農田土壤有機碳與粘粒含量的相關關系和粘粒含量有關,當粘粒含量為20%～25%,有機碳與粘粒的相關性較高,當粘粒含量大于30%時,有機碳與粘粒呈負相關趨勢。在區(qū)域尺度上,全氮、容重、全磷是影響農田土壤有機碳的重要因子,在各個地貌類型區(qū)中,全氮是影響農田土壤有機碳含量的重要因子。關中平原區(qū)、渭北高塬區(qū)、丘陵溝壑區(qū)、銀川平原區(qū)、淺山丘陵區(qū)有機碳處于最高水平時的全氮閾值分別為1.39、0.95、1.33、1.38、1.64 g/kg,有機碳處于低級水平的全氮閾值分別為0.97、0.59、0.86、0.76、1.06 g/kg。3.指標變異性隨尺度的變化而發(fā)生變化,不同空間的土壤質量指標最小數據集評價結果存在尺度效應。在不同尺度間,容重、pH、全鉀、碳氮比變化較小,其余指標整體呈現出變異性隨尺度增大而增大的趨勢。通過分析指標變異性影響因素可知,指標變異性受到自然因素及人為因素的雙重影響,但影響程度有所不同。相對于單因素對土壤質量指標的影響,綜合影響因素對指標的影響更大,這也表明,指標的變異性不僅僅是單因素的作用結果,而是多個因素相互作用造成的。所以,在進行土壤質量評價時,應綜合考慮多方面因素,尤其是在研究尺度范圍內,地形、土類、管理措施多樣性程度較高時。此外,氣候類型及農田管理措施在尺度上推或下推過程中均會發(fā)生相應變化,這導致土壤質量指標的變異性與相關性也隨之變化,最終導致不同空間尺度所篩選的最小數據集評價指標的代表性存在尺度效應。在指標篩選過程中,應充分重視針對性和區(qū)域性原則,所選指標應能夠反映區(qū)域問題,進而在降低成本的前提下提高土壤質量評價的準確度和應用性。4.以典型縣為基礎、“農田類型—地形—土類”組合斑塊為單元,建立了尺度上推模型,從區(qū)域尺度上探討了黃土高原農田土壤質量及其空間分布特征。從區(qū)域尺度上來看,黃土高原全區(qū)農田土壤有機質、全氮含量匱乏,全磷、全鉀、速效鉀和表層有效磷含量相對充足,處于較高水平,丘陵溝壑區(qū)亞表層有效磷含量極其缺乏。關中平原區(qū)農田土壤壓實問題突出,表層土壤有43%的面積處在1.4～1.5g/cm3之間,亞表層有97%的面積處于1.5～1.6g/cm3之間,此外,銀川平原區(qū)和渭北高塬區(qū)亞表層土壤分別有84%和45%的面積容重值處于1.4～1.5g/cm3之間。以黃土高原地區(qū)最高農田土壤質量作為參照,全區(qū)以五級和六級為主,面積占比分別為79%、20%,主要分布在關中平原區(qū)、汾河谷地、晉西豫北山地、渭北高塬區(qū)、丘陵溝壑區(qū)中部和西南部及銀川平原區(qū)的西部。六級土壤質量主要分布在丘陵溝壑區(qū)。亞表層土壤質量以六級(57%)和七級(31%)為主,六級土壤質量主要分布在渭北高塬區(qū)和銀川平原區(qū)西部,丘陵溝壑區(qū)六級和七級分別占55%和45%,在關中平原區(qū)和銀川平原區(qū)的東部土壤質量為八級和九級,土壤質量較低。
[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.
【學位授予單位】：西北農林科技大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：S151.9
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本文編號：1945410