Development of soil organic matter measurement system

Abstract

We managed to create a self-developed sensor system, which is based on the simultaneous reflectance measurements at a 660 and 940 nm wavelength. The ratio of the reflectance refers to the concentration of the soil organic carbon (SOC). This instrument has a calibration range of 1.19 to 6.05 SOC%. The SOC content of twenty-six soil samples was measured by the self-developed system and a standard spectrophotometric method and we found that the SOC estimation in the self-developed system had a good approximation and the differences ranged from –27.72% ~ + 6.99%. We found a strong correlation between the data of the reference measurements (R<sup>2</sup> = 0.73) and the values indicated by our self-developed sensor system (Reference (SOX%) =1.4857 × E (SOC%) – 0.7393). This measurement system is easy to use and displays and records the data in real time. This allows one to map an agricultural production area based on the SOC concentration using its built-in GPS unit.

Evaluation of spectral data based soil organic carbon content estimation models in VIS-NIR

“…In addition to the current study, previously developed models based on similar or different principles were collected to evaluate the accuracy of VIS-NIR spectroscopy in SOC determination. Measurements were made using RED and NIR reflectance in a study by Béni et al (2021). The values were determined by their patented instrument and compared with SOC results for different soil types in the reference laboratory study.…”

“…After selecting SOC-sensitive wavelengths based on PCA and SD results in the 400-2500 nm range, spectral indices were set using the most sensitive, and the least sensitive wavelengths. Spectral indexing is a common practice in the monitoring of soils in remote sensing studies (Nagy et al, 2014;Babaeian et al, 2019;Mohamed et al, 2020;Béni et al, 2021). The simple linear regression method was used to generate a model to estimate SOC based on 60 samples.…”