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应用高光谱技术阐释土壤含水率光谱规律及对土壤含水率进行定量分析,为精准农业地表土壤水分的快速测定提供参考。该文以吉林省黑土土类中的黑土亚类土壤为研究对象,利用ASD FieldSpec FR便携式光谱仪在室内环境下对不同含水率的土壤样本进行光谱反射率测量和特征分析;通过对土壤样品高光谱反射率进行对数、倒数、一阶微分以及反射率倒数的一阶微分、反射率对数的一阶微分变换,运用统计分析中的相关系数计算进行了光谱反射率与土壤水分的相关分析,并提取了土壤光谱特征波段;采用逐步多元线性回归方法和指数模式分析法,进行了高光谱土壤含水率定量反演。研究结果表明,在低于田间持水率状况下,黑土土壤光谱反射率及其反射率一阶微分和反射率对数一阶微分变换的敏感波段主要集中在400～410、1400～1850和2050～2200nm范围内,其中2156nm处与土壤水分相关系数最高,达0.89;在波长1328、1439、1742和2156nm处,采用反射率对数一阶微分所建立的黑土土壤含水率预测方程的预测精度最好,决定系数为0.931。黑土土壤含水率高光谱反演模型的建立为土壤水分的快速测定提供了新的途径。
The application of hyperspectral technique to interpret the spectral rules of soil moisture content and the quantitative analysis of soil moisture content provide a reference for the rapid determination of precision agricultural surface soil moisture. In this paper, the black soil subsoil in Jilin Province was selected as the research object. The ASD FieldSpec FR portable spectrometer was used to measure the spectral reflectance and analyze the characteristics of soil samples with different water contents in indoor environment. Reflectance Logarithm, reciprocal, first order differential and first order of reflectivity reciprocal differential and logarithmic first order differential transformation, the use of statistical analysis of the correlation coefficient calculation of spectral reflectance and soil moisture correlation analysis, The spectral bands of soil spectra were extracted. The regression of hyperspectral soil moisture content was carried out by using stepwise multiple linear regression and exponential mode analysis. The results show that under the condition of field water holding capacity, the sensitive bands of spectral first-order differential and first-order differential of reflectivity and first-order differential transformation of soil reflectance are mainly concentrated in the range of 400-410, 1400-1850 and 2050 ~ 2200nm, of which the correlation coefficient with soil moisture was the highest at 2156nm, reaching 0.89. The predictive accuracy of soil moisture prediction equation of black soil established by logarithm first-order differential at the wavelengths of 1328, 1439, 1742 and 2156nm was the highest Well, the decision factor is 0.931. The establishment of hyperspectral inversion model of soil moisture in black soil provides a new approach for the rapid determination of soil moisture.