Abstract: A soil carbon sensor includes a probe body for placement into soil, a first detector supported by the probe body that transmits a frequency-modulated signal into the soil. The first detector includes a first electrode configured responsive to a moisture content and bulk density of the soil. A second detector is supported by the probe body and transmits an amplitude-modulated signal into the soil. The second detector includes a second electrode configured responsive to a soil organic carbon content of the soil. A processor is arranged in signal communication with the first and second detectors, the processor configured to generate and control the transmission of the frequency and amplitude modulated signals to monitor the first electrode to capture an impedance measurement indicative of the moisture content and bulk density, and to monitor the second electrode to capture a current measurement indicative of the soil organic carbon (SOC) content.