Pollution of agricultural land is ubiquitous in oil-producing regions. The intent of this study was to evaluate the influence of various hydrocarbons on soil catalase and dehydrogenase activity. The experiment consisted of a known quantity of soil treated with varying amounts of various hydrocarbons and allowed to stand for four, eight and twelve days. On each of these days, catalase and dehydrogenase activities were analyzed using standard methods. The results showed a significant increase (p kerosene > diesel > motor oil. Also, a significant increase (p Say no to plagiarism. Get a custom-made essay on “Why violent video games should not be banned”? Get an original essay In general, i The effect of hydrocarbons is similar to that of kerosene > diesel > gasoline > motor oil The overall results showed that hydrocarbons disrupt soil enzyme reactions Introduction Petroleum-derived chemicals are employed in many ways, such as household solvents and specialty chemicals, important hydrocarbon pathways pollute the human environment (Kenny et al., 2002; Achuba et al. 2014). Furthermore, mechanized agriculture employing heavy machinery contributes its share to pollution of agricultural land during the collection or storage of petroleum oils, as well as unguided disposal of spent petroleum wastes in the natural environment (Odjegba and Sadiq 2002) Soil pollution alters the state of nutrients thereby decreasing their capacity. productive (Achuba and Iserhienrhien, 2018) Enzymes are important components of the soil that are responsible for the biochemical reactions of the soil because they participate in the conversion of organic substances into nutrients for plants (Zahir et. al., 2001; Achuba, 2010; Navnage et al., 2018). The previous report mentioned spent oil perturbation of soil enzyme activities (Achuba and Peretiemo-Clarke, 2008). The study involves the determination of two main soil enzymes, catalase and dehydrogenase activities, which are vital in soil biotransformation reactions (Li et al., 2005; Achuba and Peretiemo-Clarke, 2008). These enzymes are sensitive to pollution and their values ​​are used as a tool for toxicity tests (Navnage et al., 2018). Therefore, the aim of this study was to determine the effect of hydrocarbon-treated soil (kerosene, diesel, motor oil, and gasoline) on catalase and dehydrogenase activities in soil. Materials and methods Warri Refining and Petrochemical Company supplied the petroleum hydrocarbons. The soil (sand 84%, silt 5.0%, clay 0.4% and organic matter 0.6%, pH 6.1) was obtained from vacant agricultural land in Site II of Delta State University, Abraka. The soil was sieved using 2 mm mesh after air drying. Each of the polyethylene bags (1178.3 cm3, 15 cm deep) was filled with the soil sample (1600 g) and randomly divided into six groups of five replicates. Groups one through five were treated as follows: 0.1%, 0.25%, 0.5%, 1.0%, and 2.0% (v/w) of each of the petroleum hydrocarbons, respectively. The sixth group served as a control (0.0%). In the first group, 1.0 ml of kerosene, corresponding to 0.1%, was added and mixed carefully by hand until homogeneous. The procedure was adopted for 0.25%, 0.5%, 1.0%, 1.5% and 2.0% and subsequently applied to the other hydrocarbons. Preparation of the extract and assay of catalase activity The extract for the determination of catalase was prepared following the protocol described previously (Achuba and Peretiemo-Clarke, 2008) and the activity of the enzyme assayed as.