Quantitative Mapping of Soil Nitrogen Content Using Field Spectrometer and Hyperspectral Remote Sensing

Mapping and dating soil total nitrogen is of great importance in soil use and evaluation. In this study we examine the feasibility of soil nitrogen content by using hyperspectrally reflective remote sensing methodology. This technique was tested in Hengshan County, northern Shanxi Province of China. The soil reflectance properties of samples were measured in the laboratory by ASD field spectrometer. The correlation analysis related with nitrogen content was processed with the spectral reflectance factors (the first derivative reflectance, the logarithmic reflectance and absorption depth). The results show that the first derivative reflectance at sensitive bands of 480 nm, 980 nm and 2210 nm has more notable correlation coefficient as compared to other parameters. Knowing these correlations we were able to build up the multivariate regression model and map the soil total nitrogen content by calculating each pixel of Hyperion image. The accuracy assessment by relating predicted nitrogen values with measured ones of a linear regression showed that the map is reliable and significantly correlative with known stabilization processes throughout the study area. Moreover, this quantitative methodology developed in this study for mapping soil total nitrogen content can also be applied to other regions throughout the world.