Inversion of available nitrogen content in hilly paddy soil of southern China based on hyperspectral characteristics

Abstract

To analysis the relationship between the hyperspectral reflectance in the visible / near infrared bands and available nitrogen( AN) in paddy soil in southern China hilly areas,the authors collected the hyperspectral reflectance of paddy soil and made analysis with spectral analysis methods with the purpose of discovering the spectral characteristics of field reflectance and its influencing factors. The spectral indices were derived,and then paddy soil AN predicting model based on the correlation between AN content and spectral indices was built. The results were as follows: The different AN content paddy soil reflectance curves showed the tendency that,with the increase of AN content,the spectral reflectance decreased and the absorption depth became greater; by analyzing the correlation coefficient of paddy soil AN content and 16 kinds of mathematical transformations of spectral reflectance,the sensitive wavelengths were extracted,which were 694 nm,2 058 nm and 2 189 nm; the predicting model for paddy soil AN content was built with spectral resample reflectance at 694 nm,2 058 nm and 2 189 nm as independent variables and AN as dependent variable,and the coefficients of determination R2 of the model was0. 56,suggesting that the model is quite good in stability and predictability.