An Innovative Prototype to Measure Carbon Dioxide, Ethylene, and Nitric and Nitrous Oxides in the Soil Air

Abstract

ABSTRACT Agricultural intensification has increased the consumption of inputs, mainly fertilizers, which may increase emissions of greenhouse gases (GHG). The improvement of our knowledge on GHG dynamics in the soil is mandatory to optimize the use of fertilizers and reduce environmental impacts. We developed an electronic sensor prototype based on Arduino to monitor concentrations of carbon dioxide (CO2), ethylene (C2H4), ammonia (NH3), and nitrogen oxides (N2O/NOx) in the soil air in a greenhouse experiment with soybean (Glycine max L.) under two treatments: single inoculation (Bradyrhizobium spp.) or triple co-inoculation (Bradyrhizobium spp. Azospirillum brasilense and Pseudomonas fluorescens) in a completely randomized design. One-way analysis of variance, as well as correlation between plant traits at 35 days of emergence and the average daily concentration of gases in the soil air were performed. Although not affecting plant growth or yield-related traits, co-inoculation increased CO2, while decreased NOx concentrations compared with single inoculation, whereas C2H4 emission changed with the plant growth stage. Although co-inoculation increased respiration, decreased N losses by denitrification, mitigating the total emissions of GHG. The prototype showed to be efficient for monitoring GHG across the experiment at a low cost and easy use, contributing for monitoring GHG concentrations in the soil air.