延安市土壤养分空间变异及耕地地力评价

发布时间：2018-03-03 21:28

  本文选题：延安市　切入点：土壤养分　出处：《西北农林科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：以县域测土配方施肥项目为依托,选取陕西省延安市各区县耕地地力评价土壤采样检测数据,其中,有机质31428个,有效磷31201个,速效钾31248个,全氮23816个,速效氮30252个以及pH30907个,应用地统计学与GIS相结合、层次分析和多元回归分析相结合的方法,分析延安市土壤养分空间变异和影响因素,进行区域耕地地力评价。取得的主要研究成果如下:(1)研究区土壤有机质含量平均值为9.24 g/kg,位于陕西省第二次土壤普查土壤养分含量分级标准的第7级,土壤全氮、有效磷、速效氮含量平均值分别为0.59 g/kg、9.94 mg/kg、40.46 mg/kg,均位于分级标准的第6级,速效钾含量平均值为121.57 mg/kg,符合3级标准,土壤酸碱度pH值在6.8~9.4之间,平均值为8.09,符合4级标准。延安市土壤养分除速效钾外均处于较低水平,土壤整体呈弱碱性。(2)研究区土壤有机质、全氮、速效氮拟合的最优半方差函数模型为球状模型,有效磷和速效钾拟合的最优半方差函数模型为指数模型,pH值拟合的最优半方差函数模型为高斯模型。6种土壤养分块金系数均介于34%~53%之间,均属于中等程度相关;土壤养分分维数较高,均介于1.832~1.939之间。综合半方差函数、分维数分析,研究区6种土壤养分空间相关性明显。(3)研究区土壤有机质呈南高北低,西高东低;土壤pH、速效氮呈南高北低,东高西低;土壤全氮从西南向东北方向递减;土壤速效钾、有效磷呈南高北低格局。(4)研究区土壤养分对年降水量、≥10℃积温和日照时数等气象因子均在0.01水平上达到显著相关,年降水量、日照时数对速效钾和有机质影响强于其他养分,≥10℃积温对速效氮的影响最大;除有效磷与坡度不相关外,均与海拔、坡度和起伏度等地形因子在0.01水平上呈显著相关性;地貌类型对土壤养分含量有影响,土壤类型对土壤养分含量影响显著。(5)研究区耕地总面积4266.64km2,其中,一级地16.80%,二级地18.52%,三级地10.65%,四级地21.78%,五级地24.55%,六级地7.70%,一、二、三级地主要分布在延安南部洛川-黄陵-富县一带的黄土塬地貌区和东部延川-延长-宜川一带的黄土塬、梁地貌区,四、五、六级地大面积分布在延安北部各县。
[Abstract]:Based on the county soil test and fertilizer application project, the soil sampling data of farmland land fertility evaluation in Yanan City, Shaanxi Province were selected. Among them, 31428 organic matter, 31201 available phosphorus, 31248 available potassium, 23816 total nitrogen, 30252 available nitrogen and pH30907. The spatial variation and influencing factors of soil nutrients in Yan'an were analyzed by combining geostatistics with GIS, hierarchical analysis and multiple regression analysis. The main results obtained are as follows: 1) the average value of soil organic matter content in the study area is 9.24 g / kg, which is located in the 7th grade of the classification standard of soil nutrient content in the second soil census of Shaanxi Province, with total nitrogen and available phosphorus in the soil. The average available nitrogen content was 0.59 g / kg ~ 9.94 mg / kg ~ (-1) mg 路kg ~ (-1) 路kg ~ (-1), respectively, which were in the sixth grade of the classification standard, and the average available potassium content was 121.57 mg / kg, which was in accordance with the third grade standard, and the pH value of soil pH was between 6.8 mg / kg and 9.4, respectively. The average value is 8.09, which accords with the 4th grade standard. The soil nutrients in Yan'an are at a lower level except available potassium, and the soil is weak alkaline. 2) the optimal semi-variance function model for fitting soil organic matter, total nitrogen and available nitrogen in the study area is spherical model. The optimal semi-variance function model for fitting available phosphorus and available potassium was exponential model and pH value fitting. The best semi-variance function model was Gao Si model. The gold coefficients of 6 kinds of soil nutrients were between 34% and 53%, which were all of moderate correlation. The fractal dimension of soil nutrients was between 1.832 and 1.939.Comprehensive semi-variance function and fractal dimension analysis showed that the spatial correlation of 6 kinds of soil nutrients in the study area was obvious. The soil organic matter in the study area was high in the south and low in the north and the east in the west. Soil pH, available nitrogen was high in the south, low in the north, low in the east and high in the west; total nitrogen in the soil decreased from southwest to northeast; available potassium and available phosphorus were in the pattern of high and low in the south and north. Meteorological factors such as accumulated temperature 鈮，

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