[Estimation of the TN and SOM contents in soil from GAN NAN navel orange plant area by NIR diffuse spectroscopy].

The soil sampled from GAN NAN navel orange plant area was selected as research object, and the feasibility of analyzing the total nitrogen (TN) and soil organic matter (SOM) of soil was investigated by near infrared spectroscopy (NIR) techniques in the wavelength range of 4 000 - 7 500 cm(-1). Different pretreatment methods including multiplicative scatter correction (MSC), first derivative(1st D), second derivative (2nd D), Savitzkv-Golay (SG), standard normalized variate (SNV) and baseline were used. The partial least square regress (PLS) was built for the calibration models. The best TN model using SG pretreatment features the prediction correlation coefficients (r(c)) of 0.802, the root mean square error of calibration (RMSEC) of 2.754, the calibration correlation coefficients (r(p)) of 0.715, and the root mean square error of prediction (RMSEP) of 3.077 in the wave-length range of 4 000 - 7 500 cm(-1). The best SOM model using SNV pretreatment has r(c) of 0.848, RMSEC of 0.128, r(p) of 0.790, and RMSEP of 0.152. The results showed that the NIR diffuse reflectance can be used for quick estimate of the TN and SOM contents in soil with the wavelength range of 4 000 - 7 500 cm(-1).