The influence of herbicides on greenhouse gases emissions from soil: a bibliometric analysis

Agriculture is an important factor shaping gas exchange in the soil-atmosphere system. An important mechanism of agricultural impact is through the modulation of the living conditions of soil microorganisms responsible for the biological formation and utilisation of greenhouse gases. In this respect, agrochemicals play an important role. Fertilisers in particular have received much attention to date. The effects of soil supplementation, particularly with mineral nitrogen-containing fertilisers or organic fertilisers, on the microbial communities responsible for GHG transformation are well documented. Far less attention has been paid to other categories of agrochemicals, including herbicides. Meanwhile, the intensification of agriculture and the introduction of herbicide-resistant, transgenic crops involves the introduction of huge quantities of these chemicals (in the thousands of tonnes per year) into the environment. As a result of inaccurate dosing and with dead plant biomass, these compounds end up in the soil environment. The current paper presents a synthesis of information on the current state of knowledge regarding the effects of 4 commonly used herbicides worldwide (glyphosate, glufosinate, atrazine and 2,4-D) on the cycles of the most important greenhouse gases. VOS wiever software, equipped with text mining functionality was used to construct and visualise co-occurrence networks of important terms extracted from a body of scientific literature. An analysis of bibliographic databases for co-occurrence of key words such as "methane", "nitrous oxide", "carbon dioxide" and "greenhouse gas" - separately for each of the studied herbicides revealed that knowledge in this area is scarce and fragmentary. In the context of effects on greenhouse gas balance, only a few papers were recorded for glyphosate and atrazine and none for glufosinate or 2,4-D. In view of increasing global warming and the intensification of agricultural activity, it is important to complete the knowledge in this area.

Acknowledgements

This work was supported by the Project “Effect of glyphosate on the biological methane oxidation in agricultural soils”, no. 2021/41/B/NZ9/03130 which was financed by National Science Centre Poland.