Yield and Heavy Metal Content of Wastewater-Irrigated Cauliflower and Soil Chemical Properties

A two-year field study was conducted to determine the effects on the growth, yield, heavy metal content, and water use of cauliflowers and on the soil chemical properties of irrigation with reclaimed urban wastewaters (filtered, aerated, diluted) by comparing with fresh water under semi-arid climate conditions. Cauliflower curd yield, water use efficiency, and heavy metal contents were found to be the highest in the filtered wastewater application. Cadmium (Cd) content was just over the critical level for human health. Filtered and aerated wastewater applications created higher soil salinity, organic matter, and total nitrogen (N), dipotassium oxide (K₂O), and phosphorus pentoxide (P₂O₅) contents. Copper (Cu), iron (Fe), and manganese (Mn) contents in the surface soil were also found to be significantly higher. Treated-wastewater irrigation could increase cauliflower yield and water productivity. However, higher heavy metal contaminations under these conditions may increase health risks. Therefore, the diluted wastewater application may be preferred, but it must be utilized while taking human health into account.