Soil pore space gas probes for use in agricultural research

Abstract

Increasing agriculture intensification to meet global demand has sparked great interest in economic and environmentally sustainable cropping systems. One important measure of environmental sustainability is greenhouse gases production, which can be altered with soil health promoting practices such as cover cropping and no-tillage. Previously, the measurement of gas concentration and production in soils has been cost-prohibitive for factorial designs in agricultural research and may inhibit field operations. This study aimed to provide an affordable method for measuring below ground pore space concentrations of greenhouse gases. Testing was conducted in Lubbock, TX in 2019 in a cotton monoculture with gas sampling conducted about a month after fertilizer applications. Probes were installed at 7.5 and 15 cm depths and sampling was conducted with a portable Fourier-transform infrared gas analyzer. It was determined that consistent values of carbon dioxide (CO2) concentration were measured with average CO2 concentrations across tillage systems of 570 µL L−1 at 7.5 cm and 610 µL L−1 at 15 cm in June and 1050 µL L−1 at 7.5 cm and 1380 µL L−1 at 15 cm in August. Compared to pore space concentrations from similar soil moisture conditions, our measurements were highly comparable. Soil pore space probes used in this study provided comparable measurement of soil gas concentrations at a low per-plot cost. In addition, our probes were able to be installed with minimal soil disturbance allowing for measurement in already established no-tillage systems and allowed for field operations to be conducted by placing probes within the crop row.