Influence of Pesticides and Mineral Fertilizers on the Bacterial Community of Arable Soils under Pea and Chickpea Crops

Fertile Chernozems of Southern Russia are of great value, so it is important to study the impact of agricultural activities on the soil quality. Changes in taxonomic composition and alpha-diversity of microbial communities of agricultural soils occupied by pea (Pisum sativum L.) and chickpea (Cicer arietinum L.) in response of cropland management were studied. A field experiment was conducted under four different conditions: (1) control, (2) mineral fertilizers (NPK) application alone, (3) pesticides application alone, and (4) fertilization combined with pesticides. The taxonomic composition of the soil bacterial community was studied by amplification and sequencing of the 16S rRNA gene. The predominance of Actinobacteria (17.7-32.3%), Proteobacteria (17.7-28.2%), Planctomycetes (10.1-21.3%), Acidobacteria (5.3-11.1%), Chloroflexi (1.0-7.1%), Gemmatimonadetes (2.5-8.0%), Bacteroidetes (3.6-11.3%), and Verrucomicrobia (3.9-9.2%) was noted. Introduction of pesticides led to an increase in the relative abundance of Chlorobi and Gemmatimonadetes. The time of sampling was the main significant factor determining the differences in the structure of soil microbial communities. All treatments did not have a significant effect on the alpha-diversity of the studied soils. Thus, treatment with mineral fertilizers and pesticides does not have a significant negative effect on the bacterial community of cultivated soils.