Abstract: In this study, near infrared reflectance spectroscopy (NIRS) was used to determine the organic carbon (OC), total nitrogen (TN), and C/N ratio in black soil of Northeast China. Based on the 3699-12000 cm^-1 NIRS of 136 black soil samples collected in 2004-2005, and by  using. partial least square (PLS), the related quantitative models were established. Leave one out cross validation showed that the OC and TN were well predicted, with the values of coefficient of determination (R²) being 0.92 and 0.91, RPD (the ratio of standard deviation of validation set to root mean square error of cross validation) being 3.45 and 3.36, and correlation coefficient (r) being 0.94 and 0.93 respectively, suggesting that NIRS had the potential to predict the OC and TN in black soil of Northeastern China. However, the C/N ratio was poorly predicted, with R²=0.61, RPD=1.61, and r=0.74, indicating that NIRS could not give reasonable prediction for the C/N ratio in black soil.

Key words: black soil, near infrared spectroscopy, organic carbon, total nitrogen, C/N, partial least square, sugarcane-soybean intercropping, reduced nitrogen rate, nitrogen balance, ammonia volatilization, nitrogen leaching.