Abstract:

To optimize the calculation speed of the soil organic matter （SOM） content prediction model， 50 soil samples were used to extract and screen the characteristic spectral bands of SOM by using Pearson correlation coefficient analysis method. The results showed that the reflectance spectra of the soil was strongly negatively correlated with SOM content in the range of 555~662 nm， with a characteristic band at 601 nm. After different preprocessing methods， the reflectance spectra of soil and SOM content showed a strong correlation， and the characteristic bands increased， mainly around 601， 1 221， 1 410， 1 665， 1 880， 2 110 and 2 200 nm. By analyzing the Pearson correlation curves between the reflectance spectra at different soil moisture levels and SOM content， the characteristic bands were observed around 601， 1 450， 1 930 and 2 200 nm. With an increase in soil moisture content， the correlation of the characteristic band at 601 nm gradually weakened， while the correlation of the moisture-related characteristic bands at 1 450， 1 930 and 2 200 nm increased. When the soil moisture content exceeded 10%， the reflectance spectra of soil and SOM content showed a positive correlation. The identified characteristic bands of SOM and soil moisture provided theoretical support for the development of a rapid detection model for SOM.

Key words: soil organic matter, visible-near infrared reflectance spectroscopy, Pearson correlation coefficient, soil moisture

摘要：

为优化土壤有机质含量预测模型运算速度，以50份土壤有机质为例，利用Pearson相关系数分析法对土壤有机质的特征波段进行提炼筛选。结果表明，土壤样品的反射光谱与土壤有机质含量在555~662 nm波段范围内呈较强负相关，显著特征波段为601 nm；经过不同预处理后的土壤反射光谱与土壤有机质含量呈较强的相关性，显著特征波段增加，主要体现在601、1 221、1 410、1 665、1 880、2 110、2 200 nm波段附近。对不同土壤含水率的反射光谱与土壤有机质含量之间的Pearson相关曲线进行分析发现，显著特征波段主要体现在601、1 450、1 930、2 200 nm波段附近，随着土壤含水率的增加，土壤有机质的特征波段601 nm的相关性逐渐减弱，土壤水分的特征波段1 450、1 930、2 200 nm的相关性逐渐加强；土壤含水率超过10%，土壤反射光谱与土壤有机质含量呈正相关。研究获取的土壤有机质特征波段和土壤水分影响波段，为土壤有机质快速检测模型的建立提供理论支撑。

关键词: 土壤有机质, 可见-近红外反射光谱, Pearson相关系数, 土壤水分