Spectroscopic Determination of Soil Organic Carbon and Total Nitrogen Content in Pasture Soils

Abstract

To explore a convenient and efficient approach for determining the content of soil organic carbon (SOC) and total nitrogen (TN), this study focused on capturing the features value of SOC and TN by applying the method of wavelet analysis and wavelet transformation. The soil used in the study was sampled from the pastures in Fukang City of Xinjiang Uygur Autonomous Region, China. The soil samples were tested by using a combined approach of chemical analysis and spectroscopy measurements. It was found that reflectance at 400–2500 nm was more strongly correlated to SOC than to TN. The maximum negative r values between reflectance and SOC + TN at 2309 nm was –0.81 (P < 0.01), and SOC/TN at 1693 was –0.48 (P < 0.05). The maximum correlation coefficient between SOC, TN, and wavelet coefficient was more than 0.96 compared to the relationship among SOC, TN, and spectral reflectance. By using continuous wavelet transformation (CWT), it was found that the maximum correlation coefficients were 0.981 at 2328 nm of scale 13 for SOC and 0.968 at 1741 nm of scale 6 for TN. These results also suggested that wavelet analysis was a better method for capturing the absorption features of soil properties and determining SOC and TN content.

Keywords:

• Absorption feature of soil properties
• hyperspectral
• soil organic carbon (SOC)
• spectral features
• total soil nitrogen (TN)
• wavelet analysis

Acknowledgment

We are grateful to the chief editor and anonymous reviewers for their illuminating comments.

Funding

This work was supported by the Key Project of Chinese National Programs for Fundamental Research and Development (973 Program, 2010CB950702), the China’s High-Tech Special Projects (863 Plan, No. 2007AA10Z231), and Asia-Pacific Network for Global Change Research Project (ARCP2011-06CMY-Li).

Notes

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