基于EM38-MK2干旱区薄膜覆盖棉田土壤剖面电导率解译研究

发布时间：2018-11-25 14:23

【摘要】：土壤盐渍化是在各种自然环境因素和人为活动因素的综合作用下,土壤中易溶盐分在土壤表层积累的现象或过程。土壤盐渍化会使土壤的理化性质恶化,削弱和破坏土地生产力,降低土壤养分的有效性,引起植物“生理干旱”,导致凋零死亡,其严重后果将直接威胁生态、经济和社会的可持续发展。随着全球人口的剧增,对粮食需求日益增长,农田已成为人类存亡的关键,然而土壤的盐渍化灾害作为世界众多国家所面临的最严重的土地退化问题之一,严重制约农耕地的生产力,现已成为全球性严峻的生态问题。我国在《现代农业发展规划(2011-2015年)》中明确提出要“强化农业科技”,在农业应用方面要“大力推动精准作业”、“遥感监测、灾害预警”的目标与任务。由此可见,土壤盐渍化问题作为影响干旱半干旱区域社会经济发展无法忽视的生态问题之一,切实地开展绿洲农业土壤盐渍化监测预警相关研究,将适用于地区发展实情的技术手段研究成果化,并推广到农业发展的实践中去已然迫在眉睫。本文通过大地电磁感应仪(EM38-MK2型)与手持GPS设备,在5月棉花发芽期间,结合野外采集的土壤剖面电导率数据,对于田县绿洲研究区典型薄膜覆盖下的棉田土壤剖面电导率展开研究。本文研究结论主要有:1)通过EM38-MK2电导仪对田间采集了217个样点的土壤表观电导率的基础上,使用地学统计学相关知识结合ARCGIS软件对此时棉田的电导率分布特征进行了详细的分析,田块内中部北边的区域表观电导率最高,向其他方向辐射递减。通过对各样点不同深度下的土壤进行采样,通过室内试验分析得到EC1:5数据,继而对各采样点的土壤剖面电导率分布进行分析,第一类土壤样点的剖面电导率变化来看,均值与中位数都显示出先减小后增大的趋势。这种震荡变化的特点一方面由于漫灌使土壤剖面盐分整体向下淋洗,导致盐分在40cm以下聚集,使得土壤处于脱盐状态。第二类土壤剖面电导率显示出同样的趋势但变化程度较弱,上层处于轻度盐渍化程度,而底部处于中度盐渍化程度。第三类与第四类土壤剖面电导率呈较为均匀的变化趋势,处于轻度盐渍化与非盐渍化状态。2)在使用EM38-MK2电导仪采集了各点不同高度垂直模式下的表观电导率数据后,在前人研究的基础上,构建了以EC1.0V、EC0.5V、EC1.0V+EC0.5V和EC1.0V-EC0.5V为自变量的四种经验解译模型。并使用交叉检验的方法对四种多元线性模型进行了精度检验,结果表明以EC1.0V-EC0.5V为自变量的预测模型整体效果最优。另外,还使用了基于物理电磁学原理的线性响应模型对不同高度下的表观电导率进行直接转换,以得到土壤剖面的电导率数据,结果表明该方法精度不如经验模型,可以预测出土壤剖面电导率的变化趋势,但对于土壤层间电导率变化的细节无法有效的进行预测。
[Abstract]:Soil salinization is a phenomenon or process of accumulation of soluble salt in soil surface under the combined action of various natural environment factors and human activities. Soil salinization will worsen the physical and chemical properties of soil, weaken and destroy the land productivity, reduce the availability of soil nutrients, cause plant "physiological drought" and lead to death, and its serious consequences will directly threaten the ecology. Sustainable economic and social development With the rapid increase of global population and the increasing demand for food, farmland has become the key to the survival of human beings. However, the salinization of soil is one of the most serious land degradation problems faced by many countries in the world. Seriously restricting the productivity of agricultural land, has become a severe global ecological problem. In "Modern Agricultural Development Plan (2011-2015)", our country clearly put forward the goal and task of "strengthening agricultural science and technology", "vigorously promoting precision operation", "remote sensing monitoring, disaster early warning" in agricultural application. Therefore, soil salinization is one of the ecological problems that can not be ignored in the arid and semi-arid regions, and the relevant research on monitoring and warning of soil salinization in oasis is carried out. It is urgent to apply the research results of technical means suitable for regional development to the practice of agricultural development. In this paper, through the use of EM38-MK2 and hand-held GPS equipment, during the cotton germination in May, the electrical conductivity data of soil profile collected in the field are combined. The conductivity of soil profile of cotton field under typical film mulching in oasis research area of Yutian County was studied. The main conclusions of this paper are as follows: 1) on the basis of the apparent conductivity of 217 soil samples collected by EM38-MK2 conductometer, The characteristics of electrical conductivity distribution in cotton field were analyzed in detail by using geostatistical knowledge and ARCGIS software. The apparent conductivity in the north of the middle part of the field was the highest and the radiation decreased in other directions. Through sampling the soil at different depths and analyzing the EC1:5 data in the laboratory, the conductivity distribution of the soil section of each sampling site is analyzed. The change of the conductivity of the first kind of soil sample is analyzed. Both mean and median showed a tendency to decrease first and then increase. On the one hand, the salt in soil profile was washed down by flooding, which led to the accumulation of salt below 40cm, which resulted in the desalination of soil. The conductivity of the second kind of soil profile showed the same trend but the degree of change was weak, the upper layer was in the degree of slight salinization, and the bottom was in the degree of moderate salinization. The conductivity of the third and fourth types of soil profiles showed a more uniform change trend, and was in the condition of mild salinization and non-salinization. 2) after collecting the apparent conductivity data of different vertical models of different points by using EM38-MK2 conductance meter, On the basis of previous studies, four empirical interpretation models with EC1.0V,EC0.5V,EC1.0V EC0.5V and EC1.0V-EC0.5V as independent variables are constructed. The method of cross test is used to test the accuracy of four multivariate linear models. The results show that the prediction model with EC1.0V-EC0.5V as independent variable has the best overall effect. In addition, the linear response model based on the principle of physical electromagnetism is used to directly convert the apparent conductivity at different heights to obtain the conductivity data of soil profile. The results show that the accuracy of the method is not as good as that of the empirical model. The change trend of soil conductivity can be predicted, but the details of soil interlayer conductivity change can not be predicted effectively.
【学位授予单位】：新疆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S156.41

【共引文献】