基于电磁感应的典型干旱区土壤盐分空间异质性

为研究干旱区土壤盐分空间异质性，指导农业生产实践，运用大地电导率仪（EM38、EM31）对研究区域进行移动式磁感调查，获取表观电导率（ECa）。同时，通过27个校准点的采样和ECa测量，建立土壤盐分的电磁感应解译模型。干旱区土壤盐分质量分数与EM38、EM31水平模式读数（H38、H31）显示出良好的相关性（R=0.935），可以利用ECa结合GIS和地统计学知识研究土壤盐分的空间分布。采用两种方法进行研究：一种是先利用解译模型获取磁感调查点的土壤盐分质量分数，然后进行地统计分析研究其空间分布；另一种是先利用地统计分析研究H38和H31的空间分布，然后利用解译模型通过栅格运算计算盐分质量分数，精度检验显示前者预测值与实测值之间的相关性更好（R2， 0.888＞0.873）；标准差较低（std. 0.414＜0.426），具有更高的预测精度。研究结果表明，基于电磁感应研究干旱区土壤盐分空间异质性是切实可行的，这对于土壤盐渍化的快速诊断，指导农业生产和促进精准农业的发展具有重要的意义。

Spatial heterogeneity of soil salinity in typical arid area based on electromagnetic induction

To research the spatial heterogeneity of soil salinity in arid areas for guiding the agriculture production, mobile electromagnetic induction (EM) survey with EM38 and EM31 was performed to measure apparent soil electrical conductivity (ECa). 27 calibration sites samples were selected for ECa measurements at the same time, then the EM interpretation model on soil salinity was established. The experimental results showed a good correlation between the soil salinity and the ECa data of H38 and H31 which were respectively measured by EM38 and EM31 in horizontal mode in the arid area (R=0.935). The soil salinity spatial distribution can be studied by ECa data combined with GIS and geo-statistics techniques. Two ways were introduced for research in the paper: one was that the soil salinity on EM survey sites was interpreted by the interpretation model, then the spatial distribution was studied by geo-statistics technique; the other was that the spatial distribution maps of H38 and H31 were studied by geo-statistics technique, then the soil salinity was calculated with the interpretation model by rater calculator. The precision test showed the former way had better accuracy, which the correlation between the measured values and the predicted values was better (R2: 0.888>0.873), and the standard error was less than the latter (0.414<0.426). The results indicate that the research on spatial heterogeneity of soil salinity with electromagnetic induction (EM) in arid areas is reliable, and has important significance for rapid survey on soil salinization, guidance of agriculture production and development of precise agriculture.