Carbon dioxide (CO2) is an important greenhouse gas, which affects significantly global warming and climate change (Rastogi et al., 2002). Approximately 30% of the total CO2 emissions are released by agricultural activities. It is notable that agricultural CO2 emissions increased by 27% over two decades, from 1970 to 1990 (Lal, 2004).
Primary sources of soil CO2 emissions are root respiration and degrading of organics by soil microorganisms. Soil microbial activity mainly depends on soil properties, including soil temperature, organic matter and soil moisture content (Smith et al., 2003). Increasing scientific attention is focused on understanding the role of the soil microbial community (Bautista et al., 2017; Cho-Tiedje, 2000; Mátyás et al., 2018; Mátyás et al., 2020) and nutrient cycles (Jakab, 2020; Sándor et al., 2020). It has been documented that different cultivation technologies significantly impact soil microbiological activity (Sándor et al., 2020).
Different chemicals (such as fertilizers and/or herbicides) are utilized in agricultural technologies. Use of herbicides constitutes an integral part of crop production, and one should be aware that they cause a “secondary effect” on both soil life and so called “non-target” organisms (Kecskés, 1976). Sensitive organisms are killed after using herbicides, and their remains are easily decomposed by the surviving microorganisms (Cervelli et al., 1978). At present, the selection criteria for allowed chemicals is more rigorous and stricter than over past decades, and they are restricted to smaller concentrations (Inui et al., 2001). Soil microbes play a major role in maintaining soil quality (Mendes et al., 2018; Wang et al., 2008).
In this paper, we discuss carbon dioxide emission levels of chernozem soil at the Debrecen-Látókép Plant Cultivation Experimental Station, where herbicides were applied to control the weeds. We compare results of carbon dioxide production in treated plots to untreated control parcels.
We can conclude that CO2 production decreased significantly in the soil for 11 out of the 14 herbicides. With two herbicides, Merlin SC (izoxaflutol) and Capreno (Isoxadifen-ethyl, tembotrione), there was no significant change of treated soils relative to the untreated soil, and there was only one herbicide Adengo (Bayer, Germany), which increased soil respiration slightly, but not significantly. The main sources of CO2-emissions from soil is the respiration of plant roots and of the microbial community. Therefore, a significant decrease of CO2 emission indicates a change in these parameters. One can recommend for use those chemicals, which do not cause major changes in the microbial community and do not affect life conditions of other live organisms.