Assessment of Residual Antibiotics, Biocides and their impact on Soil Microbial Communities in Irrigated Farms in Kano State, Nigeria

Abstract

This study investigates the presence and impact of residual antibiotics and biocides on soil microbial communities in irrigated farms in Kano State, Nigeria. The growing use of antibiotics and biocides in agriculture, particularly in Kano's extensive irrigated farming systems, has raised concerns about their environmental effects. This research aims to understand how these substances affect soil health by analyzing soil samples from three farms and a control site. Soil samples were collected biweekly over six months from three farms and a control area using a 6-inch sampling probe. Bacterial counts were determined using pour-plating techniques, and bacterial isolates were identified through biochemical tests. Residual antibiotics and biocides in soil were quantified using an Agilent Intuvo 9000 GC system coupled with a detector system 5977B MSD. The total bacterial counts in the farms' soil samples were significantly higher than in the control site, indicating contamination. Ceftriaxone, doxycycline, and amoxicillin-clavulanic acid were the most frequently detected antibiotics, with varying concentrations across different farms. Cypermethrin was the only biocide consistently found in soil samples, with higher concentrations in the irrigated farm soils than in the control. Several bacterial isolates exhibited resistance to multiple antibiotics, particularly amoxicillin-clavulanic acid and doxycycline. This resistance was more pronounced in soil from the farms than the control site. The presence of residual antibiotics and biocides in Kano's irrigated farms significantly affects soil microbial communities, leading to increased bacterial counts and antibiotic resistance. This study underscores the need for sustainable agricultural practices to mitigate the environmental impact of these substances.