Abstract
We developed a soil gas measurement system with a non-dispersive infrared CO2 sensor, a low-flow pump, and solenoid valves, designed to assess variations in soil CO2 concentrations within a macropore under specific cultivation conditions. The system's efficacy was evaluated through tests on the sensor's response to water vapor concentration, the system's airtightness, and the evaluation of CO2 concentrations in a macropore, using standard gases as references. The system is proved to be effective in monitoring soil gas concentrations within a macropore over a range of CO2 concentration from 400 to 7000 ppm and water vapor concentrations from 0 to 25 mmol mol-1. Further investigations were conducted using a soil column packed with Andisol, incorporating an artificial macropore beneath a young seedling with drip irrigation. Our findings suggest that CO2 gas emissions are influenced by preferential water flow, leading to increased water content at the macropore's bottom side, as determined by the water balance method.
https://ror.org/03ss88z23 
