Accumulation of pathogenic bacteria in agricultural soil irrigated with treated wastewater and their relationship with selected soil fertility variables

The use of treated wastewater (TWW) has been widely accepted globally, offering significant benefits including alleviating water scarcity. However, TWW is also a potential source of pathogens whose fate and link to soil fertility variables are not well established. Thus, this study focused on establishing the level of bacterial pathogens accumulated and their relationship with soil fertility in agricultural soil irrigated with TWW and tap water (TP). Selected groups of pathogenic bacteria (E.coli, enteric bacteria, Staphylococcus spp and Pseudomonas aeruginosa) were isolated from the irrigation treatments and soil samples. In addition, soil fertility variables (electrical conductivity (EC), soil organic carbon (SOC), nitrate (NO3), phosphorus (P), potentially mineralisable nitrogen (PMN), and pH) were analysed from the soil samples. The results revealed that using TWW for irrigation leads to a highly significant accumulation of the selected pathogens. But diluting TWW with TP reduced the accumulation of all the selected bacterial pathogens. In addition to the accumulation of pathogens, the use of TWW leads to an increase in P, EC, SOC, NO3 and pH. However, the accumulation of the selected pathogens corresponded with the decrease in N, PMN and SOC.