黑土土壤中全氮含量的高光谱预测分析

    Determination for total nitrogen content in black soil using hyperspectral data

    • 摘要: 为实现快速、准确估测土壤氮素含量水平,推动土壤信息化管理进程,该研究利用ASD2500高光谱仪在室内条件下测定了风干土壤样品的可见—近红外光谱。结果表明,通过不同的变换,光谱反射率对数的一阶导数与土壤全氮含量相关性得到增强,以400~600 nm波段范围内相关性最好。该文确定了以反射率对数的一阶导数光谱预测黑土全氮(TN)含量的最佳回归模型,模型所用的波段为可见光波段的556 nm、近红外的1 642和2 491 nm。同时,也确定了利用由可见光波段550和450 nm组成的归一化光谱指数预测黑土TN含量的最佳预测模型。模型通过验证达到较好的效果:利用反射率对数的一阶导数、归一化光谱指数对土壤TN的预测R2分别为0.863、0.829,均方根误差RMSE分别为0.122、0.152。

       

      Abstract: It provides important information for soil digital management if soil total nitrogen can be rapidly and accurately estimated. In this research, NIR-Visible spectral reflectance of soil samples was measured using ASD2500 hyperspectral meter. The results indicated that Total Nitrogen (TN) content of black soil had better relationship with the first deviation of reflectance logarithm (LOGR-FD) than the original spectrum in 400-600 nm especially. The optimum model predicting TN of black soil using derivative spectra (LOGR-FD) was established by the method of stepwise regression. The selected bands in the model are 556, 1 642 and 2 491 nm respectively. Normal Difference Index (NDI550, 450) was constructed by spectral reflectance in the bands of 450 and 550 nm, and the model was also established for TN predicting using the NDI550, 450. By validity, the above two models produced better effects: the coefficients of determination (R2) are 0.863 and 0.829 and the Root Mean Square Errors (RMSE) are 0.122 and 0.152 respectively.

       

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