Monitoring total nitrogen content in soil of cultivated land based on hyperspectral technology

Abstract

Monitoring total nitrogen content (TNC) in soil of cultivated land quantitively is significant for fertility adjustment, yield improvement and sustainable development of agriculture. Analyzing the hyperspectrum response on soil TNC is the basis of remote sensing monitoring in a wide range. The study aimed to develop a universal method to monitor total nitrogen content in soil of cultivated land by hyperspectrum data. The correlations between soil TNC and the hyperspectrum reflectivity and its mathematical transformations were analyzed. Then the feature bands and its transformations were screened to develop the optimizing model of monitoring soil TNC based on the method of multiple linear regression. Results showed that the bands with good correlation of soil TNC were concentrated in visible bands and near infrared bands. Differential transformation was helpful for reducing the noise interference to the diagnosis ability of the target spectrum. The determination coefficient of the first order differential of logarithmic reciprocal transformation was biggest (0.56), which was confirmed as the optimal inversion model for soil TNC. The determination coefficient (R2) of testing samples was 0.45, while the RMSE was 0.097 mg/kg. It indicated that the inversion model of soil TNC in the cultivated land with the one differentiation of logarithmic reciprocal transformation of hyperspectral data could reach high accuracy with good stability.