Effect of brewery wastewater irrigation on soil characteristics and lettuce (Lactuca sativa) crop in Ethiopia

Due to the shortage of water for irrigation, brewery wastewater is currently used as a source of irrigation for crops in developing countries including Ethiopia. However, there is little information about the influence of brewery wastewater on soil properties, crop nutrients and productivity in Ethiopia. Thus, this study was conducted to investigate the effect of brewery wastewater on soil physical and chemical characteristics, agronomic traits and nutrients composition of lettuce crop. Wastewater and wastewater irrigated soil samples were collected for laboratory analysis. The pot experiment was also conducted in completely randomized design (CRD) with three replications using four treatments where 100%, 75%, 50%, and 25% of the water demand was covered by brewery wastewater (WW), where one additional treatment namely 100% control water(CW) was used. The analysis of physical-chemical contents for brewery wastewater samples indicated that the values for EC, TSS, BOD, COD, HCO₃⁻, K⁺, SSP and SAR levels were above the permissible limit of the FAO irrigation water quality standard. The mean values of T, pH, TDS, NO₃⁻N, Ca⁺², Mg⁺², Na⁺, and Magnesium Hazard (MH) were below the permissible limit of the FAO standard. The pot experiment showed that 100%WW irrigated soils non-significantly (p < 0.05) enhanced the lettuce traits of leaf length, number of leaves, and fresh leaf weight by 12%, 22%, and 24% over 100%CW irrigated soils. In addition, 100%WW irrigation significantly (p < 0.05) enhanced the plant height and nutrient compositions (Ca²⁺, Mg²⁺, Na⁺, K⁺ Fe, Zn, Mn and TN⁾ of lettuce leaf. The study concludes that the brewery wastewater is saline-sodic and it affects soil characteristics and lettuce crop. Therefore, ameliorative measures such as gypsum seem to be inevitable, and, there should be continuous monitoring and evaluation for the quality status of brewery wastewater before use for irrigation.