## 1 Introduction
To counteract their occurrence, farmers use various biological, chemical, agronomic and mechanical methods. Among them, the chemical ones tend to be chosen due to their easy application, speed and efficiency [13]. Their use ensures obtaining the right amount of good-quality food and allows for its storage and transport for a long time. The usage of pesticides does not only contribute to the elimination of agrophages, but can also significantly change the soil microflora by disrupting basic biochemical processes [14]. Moreover, the presence of active substances (a.s.) in soil may cause complications in succeeding crops, while washing out pesticides deep into the soil profile carries the risk of contamination of groundwater [13]. Herbicides (MCPA and dicamba) and fungicides (thiophanate-methyl and azoxys-trobin) are often used in agricultural crops. MCPA and dicamba are herbicides with a broad spectrum of activity against various species of weeds. From another point of view, these herbicides may affect resistance to biodegradation processes and the number of specific species of microorganisms, and thus the growth and quality of crops [15; 16]. In turn, thio-phanate methyl and azoxystrobin are used in the fight against diseases during plant growth that inhibit the growth of the fungus by stopping the electron transfer between Cytb gene (cytochrome b) and Cytc (cytochrome c), which reduces the oxidation of NADH (nicotinamide adenine dinucleotide) and ATP synthesis (adenosine triphosphate) [17; 18]. The application of pesticides as substances that improve the quality of the crop also has negative environmental effects. There are reports in the literature which indicate the effect of pesticide use, including the biodiversity of soil microflora, abundance of ammonia-oxidizing bacteria, and enzymatic activity of microorganisms [13; 19]. The root zone is one of the areas with the most intense biological activity, characterized by a rich bacterial and fungal flora. It has a large impact on the uptake of nutrients by the roots [10; 13]. Soil biodiversity plays an important role in regulating and maintaining a high functional potential, contributing to soil stability and productivity. According to [PERSON] et al. [19], different groups of soil organisms play different roles in maintaining multi-functionality. For example: soil invertebrates are responsible for processing large amounts of plant and animal residues, while protists, bacteria and fungi are important in ensuring proper energy flow. It cannot be ignored that the activity of soil microorganisms depends, to a large extent, on the oxygen conditions of soil, determined by its physical and chemical properties and the influx of xenobiotic factors. The activities of dehydrogenases, catalases and ureases are considered to be important indicators determining the number and activity of microorganisms, which provide important information on the biochemical processes taking place in the medium. The activity of dehydrogenases increases proportionally to the amount of sewage sludge introduced into soil, as it is strongly correlated with the presence of organic matter and allows for assessing the influence of factors adversely affecting soil microorganisms [13]. Moreover, ureases provide information on the decomposition of nitrogenous organic compounds. According to [PERSON] and [PERSON] [20], there are significant positive correlations between soil catalase activity and organic matter content, microbial biomass, O\({}_{2}\) uptake, CO\({}_{2}\) release, ATP content, soil fertility, and dehydrogenase activity [21]. In the literature, there are many reports describing the advantages and disadvantages of using sewage sludge in crops, but there are still insufficient data available explaining the effects of sludge and pesticides on the changes that occur in soil microbial population.